quote Originally posted by Fierobsessed: the other runs into the C500 (D3) which was the temperature light. From there it makes it to the cluster, where it will be locally wired to the sunbird boost/tach.

Why on earth are you doing that?

Edit: Nevermind, I was thinking MAF rather than MAP

[This message has been edited by Will (edited 10-12-2013).]

Just a little bit of spooling and a bit of boost...



I finished the intercooler plumbing this morning, wired the pump to key on power, and filled the system with coolant and bled the air out. Seems to be working well. I may also need a lighter spring than the 11 psi spring in the blow off valve, I'm getting a bit of off throttle turbo surging sound. I've been playing with the tune and sorting out a few misc issues I've had. I've been so busy that I really haven't had the time to do many updates. But it's all turning out well!

I've been keeping busy on this project. I had to sort a couple of leaks I had to sort out, namely the turbo water fittings again. I wound up using AN $$ fittings to replace one of my custom pipes. Once that was taken care of, I did some basic tuning and drove it around a bunch. It drives great in open loop, terrible In closed loop. I have my work cut out for me tuning wise.

I've spent the last two weeks doing a complete hack on $6D, which is pretty much 96% identical to $8F. The only differences:
Calculation of map variables (due to map sensor difference)
6D has shift light logic
8F has wastegate code.

They basically took $6D and cut the shift light logic from it since 8F was an "auto only" and reused some of the ram slots for the added in wastegate code.

After doing the hack, I polled the differences between an otherwise identical $6D manual ATWX and an automatic ARYH code, and applied whichever differences I felt were applicable to my 8F code as a tuner pro v5 patch.

Then, I copied the section of code for the shift light from 6D to an open area in 8F, patched in the logic option to turn on or off the shift light code, (it was always there for some reason) added the appropriate jumps, corrected the internal addresses, and assigned new ram slots to handle the shift light timers involved.
All this to make 8F have a fully functional manual option. I also had to re-disassemble 8F to make sure I didn't make any mistakes when adding in the new code.

It is extremely time consuming doing a full hack. But with 8F being well hacked, it was a matter of lining them up next to each other. And move the descriptions over.

In the meantime, I tore the front end apart. I had installed poly bushings 5 years ago, and I had the upper control arm bushings seize to the shaft, and the shells broke free of the upper arms. It was a bad situation. I'm replacing the front bushings with rubber, and putting in Rodney Dickmans tapered front bearings and zero lash end links. Hopefully this will all make the front end as good as the day it was made.

I've come to the conclusion that poly sucks for some things, and is excellent for others. My lower control arms in the front worked excellent with poly, but I had numerous problems with it on the uppers. The rear toe and lateral links had problems, but the trailing link was perfect. At the end of the day, the larger, and less rotated poly bushings were fine. It was the little ones that had all the issues. I was considering using poly in the lower control arms, but I decided I didn't want the maintenance of poly at all.

So I'm still busy, and since the heavy code work is done, I can get back into tuning as soon as I get the front end back together.

Hands down one of the finest engineering examples on PFF. You got to love that first drive, eh?

Thanks! I've taken quite a lot of pride in the work that I have put into this. It's the best work I've done I think.

It's quite powerful but it needs so much tune work, and I'm still sorting out stuff. Like surprise leaks.

Here's one that wasn't a surprise, but rather a disappointment.


So... the axle seal is leaking a little. For now I'm going to just pretend everything is fine

I thought a bit about spark plug selection. I've had Autolite Iridium XP5243's in this engine forever, I really like these plugs.
But realizing that they are old, and still gapped to 0.060". I got a cheap set of NGK TR6 plugs and decided to put those in. 0.040" gap. But being a 3.4 DOHC Fiero, this isn't the easiest task, but quite a bit worse than the old 2.8's.

These three are perhaps the easiest to change in all of automotive history, provided you have a long enough extension.


But... once you remove the decklid, you're confronted with this catastrophe.


No problem, I'll just put the jack under the back of the cradle, unbolt the dogbone, remove the bottom two rivets from the two splash guards, remove the rear cradle bolts and lower the engine...
Now, I can just squeak the wires out, and the socket and extension in and change the plugs.


It probably took about 30 minutes to change all 6 and bolt the cradle and dog bone back in place, and put the deck lid back on.

Driving around, I didn't notice much of a difference. But at least it's something I don't have to worry about now.

I'm still playing around with tuning. It needs a ton of work. I have done some testing, and It's clear that I have a few things to sort out.
The engine hits a solid wall while boosting and I'm having trouble identifying what that wall is. But I'm afraid it might be turbo surge? It makes the characteristic sound of it. Maybe the air filter is too small and restrictive??? Either way, it's something to test.

boosted with a .060" gap? should be around .025", d/r if I read that wrong. If there is compressor surge you will hear a distinct fluttering that gets progressively louder as the rpm's climb.

As for the wall, spark timing and AFR's, where are they at when you hit the wall?

$8F has a backwards rev limiter table. For some weird reason the higher you set it the lower the limiter kicks in. If your hack copies $8F you might have the same issue.

I dropped my DOHC down until the bottom of the pan was level with the lowest part of the cradle for the most upper clearance possible.

I can get the boots off of the front 3 by pushing them forward, then pulling them at an angle towards the passenger side. I pull the plugs by dropping the socket into the hole, then the extension and then attach the ratchet. Unscrew the plug all the way, disconnect the ratchet, pull the extension until I can reach the socket and disconnect it, then use a magnetic pick up tool to get the socket and plug out. I pulled the rubber thingy out of the socket so the plug will stay in the hole- that way if the socket drops off of the magnet it wont smash the plug gap. I start new plugs with a piece of rubber hose (don't forget the anti-seize!).

Learned this method when we had a Ford Probe with the DOHC V6.

Do you have some sort of water diverter or rain guard to keep the front 3 dry? I have already had trouble with water getting in the plug wells and causing weak or no spark. Had the same problem with the Probe if I got too crazy at the car wash.

------------------
1986 SE Aero coupe.

3.4 DOHC swap is complete and running, now just have to finish the rest of the car...

quote Originally posted by Hudini: $8F has a backwards rev limiter table. For some weird reason the higher you set it the lower the limiter kicks in. If your hack copies $8F you might have the same issue.

most, if not all of the MPFI 60V6 masks are actually like this. however, most of the XDFs have the correct conversion in them. for some reason, the 8F XDF was released with a LOT of conversion errors in it.

also, .060 on a LQ1? i want to say factory gap was .045? any benefit to running it .015 larger than normal? i know the theoretical benefits, but i wasn't sure if even a stock engine was going to deal with spark blowout.

"They" don't tell you this, but you can get away with a larger gap if your gap has pointier tips, like the iridiums do. (think Tig torch, or lightning rods, pointy for that reason) And you get a healthy spark out of DIS anyway. I never had any issues with spark with the .060" N/A. Heck, I deliberately spread those plugs to that gap because I knew I could get away with it, N/A of course. But being boosted, I figured it might be the source of trouble. Still, it was not. Surprisingly.

AFR's were floating around 11.5, and timing was 8-10 degrees (weak!) and 8 lbs. Which was coincidentally registering a light knock. Unless my intercooler is garbage, or something else is wrong, shouldn't be knocking with those conservative numbers. That's why I was thinking plugs. If your fuel and timing is right and your engine is hitting the wall, and your turbo is fluttering... its probably mechanical. It could be caused by:
Compressor surge itself, which would likely be the intake filter restricting the air enough to raise the pressure differential across the compressor past the surge line.

A loss of spark, which should cause compressor surge as the turbines driving force is being removed while still under boost at WOT.

An exhaust restriction, which again will cause compressor surge due to a decrease in turbine drive, like a broken catalyst.

I'm going to try removing the air filter just to see if that is what the trouble is. It seems likely, especially if the turbo happens to be running anywhere near margin.

Hudini, you are absolutely correct, the program loads reference period, which is inverted to RPM then compares it to the cutoff value. So if you raise the value, it does in fact lower the rev limiter. But, the 8F definition did have the correct formula (1310732.000000 / X) for the value. So, it shouldn't have the inversion issue.
I haven't touched that value anyway, I see no need to rev it that high... yet

Tesmith, I couldn't really lower this engine's mounting due to the fact that the F40 transmission is naturally a bit downward leaning at the differential. its axle cup would scrape the frame if it were lowered by any real amount. Also, I am using a stock 88' fiero front engine mount, and that completely dictates height. As well as the transmission hanging lower off of the bottom anyway. So any ambition I had to lower the engine via custom mounts was fraught with complications. So I decided it would just be best to leave it where it was. I still think 1/2 hour was pretty good time to change the plugs, considering that I had to remove the decklid and swing the cradle a couple of inches. I probably won't have to do that again for a while anyway. Or so at least I hope!

quote Originally posted by Fierobsessed: But... once you remove the decklid, you're confronted with this catastrophe.

I replaced my cam covers (1992) with ones from the '96-'97 design motor. First off, they use stiff rubber sleeves instead of rigid plastic on the later plug wires. They bend enough to clear the rear window shelf without lowering the motor. A second benefit is their umbrella design that fits over a vertical wall cast into the covers. My original covers leaked badly when water got onto the motor; these seal completely.

~Neil

Ah, yes! I remember those later wires. I actually like the early wires in the back, but the newer ones for the front. I live in Las Vegas, so rain isn't much of an issue. I also found by chance, an original decklid recall weatherstrip in the U-Pull yard. So that is my only defense against water. And it hasn't been an issue. I also am a bit liberal with my Dielectric grease on this engine.

This is my second 3.4 DOHC fiero, I used to have an 85 coupe with a 96 engine. Living in rainy Long Island, I had noting but problems with the front three all the time. Here, it's just never been an issue.

I've also had issues with water getting in the front 3 plugs on mine, even with the recall strip attached to the decklid. It got to the point where the car was misfiring so badly that I couldn't drive it. About two months ago I had to come up with a solution, even if just temporary - but enough to get me through the rest of the season with the car.

I quickly made a cover out of aluminum to prevent water from getting in there. I didn't spend much time on it so it's not pretty, but it'll keep water out till I come up with a more permanent solution during the off season (which has now arrived here in MN). I tested it with a car wash and the plugs and valve cover were bone dry afterwards.

quote Originally posted by Fierobsessed: It drives great in open loop, terrible In closed loop. I have my work cut out for me tuning wise.

It took me a while to get closedloop working pretty well, the biggest problem being a stable idle and fighting the stall saver spark control to get there. I recently switched back to openloop because of the occasional idle hunt that would result from turning on the A/C, which raising idle rpm pretty much resolved but I like to keep idle near 875- 900 rpm as opposed to just shy of 1000 and at the lower limit is where most of the trouble occurred. There are so many tables with obscure titles that can actually act inversely to what the title suggests, so you can make a problem worse before figuring out you need to go in the opposite direction. If all of the major tables were defined regarding their actual function the tuning process wouldn't be so testy.

Be sure to tease out your spark dwell tables, Robertsaar did that for me and after an article with data on ignition coil dwell time relative to other load factors suggested I should adjust mine upward closer to 7 ms, I have not had another episode of spark blowout (misfire) boosting in excess of 15 psi after doing so.

Thanks for the tips. Most of the issues I've been seeing in closed loop idle appear to be excessive changes in injector pulse width. Which I assume is because I have rather large (60 lb) injectors. So I need to figure out what table or value needs to be tweaked to trim down the size of the changes in PW based on o2 swings. It just doesn't seem to like running at 13.5 - 14.7:1 at idle, It just suddenly shuts down very abruptly. 11.5 or so, runs beautifully, but that's not really what I want I'll try running the idle spark compensators from a 3.4 DOHC code and see if that helps.

Isn't dwell hard coded in the software? I cant find any reference to any tables or values at all for dwell. There are a hand full of dwell values in a small chunk of code, but It's a little hard to decipher exactly what they mean or do, or when they are called.

quote Originally posted by Fierobsessed: Thanks for the tips. Most of the issues I've been seeing in closed loop idle appear to be excessive changes in injector pulse width. Which I assume is because I have rather large (60 lb) injectors. So I need to figure out what table or value needs to be tweaked to trim down the size of the changes in PW based on o2 swings. It just doesn't seem to like running at 13.5 - 14.7:1 at idle, It just suddenly shuts down very abruptly. 11.5 or so, runs beautifully, but that's not really what I want I'll try running the idle spark compensators from a 3.4 DOHC code and see if that helps. Isn't dwell hard coded in the software? I cant find any reference to any tables or values at all for dwell. There are a hand full of dwell values in a small chunk of code, but It's a little hard to decipher exactly what they mean or do, or when they are called.

I had trouble at idle with the 60s so I can imagine what you're probably going through with even less displacement, especially if you are running a base fuel pressure in the stock 50 psi range. It's very strange but yes there is something about attempting to run stoich AFR at idle that the motors do not like and usually it manifests with a rough idle although the rpm maybe stable. You basically need to give it what it wants until you find the balance as there appears to be some fine tuning fuel delivery that I don't believe the wideband can pick up but you can feel the difference.

The tables I had to work with before my idle AFR would even budge toward stoich from a low AFR are:
FUEL INJ OFFSET VS. FUEL PUMP VOLTAGE

You're dealing with injectors that are newer and different in their characteristics relative to stock, I had to lower values to get my AFR to come up at idle as trying to do it via the idle fuel table was not working to the point where I thought the table was useless and when I adjusted the fuel table enough to get a response the results were poor and erratic. Setup a history table that tracks your pump voltage in the idle range so you'll know what your pump is seeing. You'll be able to observe the cell follower as voltage changes and note whether you need to increase or decrease fuel based on where the voltage sits with various loads on the system.

FUEL INJECTOR OFFSET VS. BASE PULSE WIDTH

This table may end up needing to be tapered off after 1 or 2 cells because theoretically larger injectors take slightly more time to open initially having more surface area pressure to overcome and weight of mechanical parts after which it tends to deliver a bit more fuel than the smaller injectors as it operates with the same linearity. I used this table to help with fine tuning things like the cooling fan and A/C coming on where the BPW would jump in desired amount.

I've been able to achieve idle AFR in the 13s but much more than that and it gets unstable in closed loop with electric loads switching on and off. Make sure you have no vacuum leaks of any kind, the problems come on slowly and progressive and can throw you for a loop until you discover how easy they can develop. I used the stock bolts in the exhaust manifolds and they made me pay about every 3 months. I have studs on the way now as it was a real headache to get at bolts barely accessible for tightening. I see you've nailed that one already.

look for "prop" tables..... they're highly involved with the injector skewing for closed loop control. there are also scalars that can come into play, especially at idle, though i would need to check my notes to see if they're actually enabled in 8F.

dwell..... those values are kind of hidden in the code, not sure of the best way to post info on them other than grabbing my disassembly and posting the entire section of code.

I spent a long morning trying to tune idle. What a pain! And I agree with what you are saying. I'm clearly following your experiences.

What I am coming across is tweaking the idle VE table is getting me to 11.5-12.0 once it gets just a little higher than that it becomes completely unstable. It doesn't feel like the pulse width, nor the AFR's are reacting to subtle table changes, but rather large changes, and then when I get close, the AFR's suddenly jump, and the engine stalls. I tried zeroing out the idle spark compensator tables, then made the small area in the idle sweet spot in the main timing table flat. This gave me completely stable timing fixed at 23 degrees. Which is what the 3.1 had in the sweet spot. This made the car have an extremely stable idle, but only when pig rich 11.3-11.5. Any higher AFR than that it starts surging and it dies. I'm going to mess with the timing value some tomorrow, and try the voltage injector offset thing while I'm at it. I've found that the EGR BPW compensation table stops effecting the fueling at right around 40-41. So I can't trim any more fuel out there. It was frustrating to try to get the idle tuned in. I feel like I've made no progress, but I am learning a lot in the process.

I've been working on 8F for a bit, I know the code fairly well. It definitely can do what I am asking it to In modified form. But trying to get the idle figured out is testing my patience. It has left me wondering which tables are truly active while idling. And, whether I am hitting limits as I'm tweaking things in. I'm not sure if there are any pulse width limitations on the injectors in synchronous firing. I'll have to consult my hack for a while.

These are things that will be the death of me! But I'll keep working on it! Thanks against for the suggestions guys! You've given me some more things to try out.

AFR VS COOLANT TEMP FOR COLD ENGINE AND CLOSED THROTTLE

Keep that table in mind, as you start to adjust tables that globally affect fueling at startup you may eventually encounter a problem with cold starts. Watch your BPW value in Tunerpro just before cranking, if the value is red and the motor starts without issue it should be fine, if it smells pretty rich you may need to reduce fueling (raise value actually) in this table some. If you encounter a problem where the motor starts okay but shortly after starts to run increasingly lean for a while and then returns to normal it is most likely this table and the lean problem lasts until it times out. I've tried the base pulse vs TPS table but found this one more effective since the TPS table did not appear to be time oriented and therefore did not fix the lean outs after starting.

[This message has been edited by Joseph Upson (edited 11-14-2013).]

I think I've found my issue. The injectors MAY be too big after all. I sent L0089 to my data stream which is the LSB for the PWM sent to the Injector driver. It's the last value that gets sent to the injector driver to tell the hardware exactly what to do.

It seems at idle, I was throwing out 18 counts, which was shooting 11.5:1 But then as I was lowering the idle VE table, slowly at first, I watched the number drop in decrements of 2. It would take around 4-5 whole % VE just to drop the counts a single decrement of 2. ONLY when this output value would change, I would see it affect the AFR's. This explains why the Idle VE table seemed to be numb to minor changes, but responsive to major ones. I could get the counts down to 12, and it would be shooting right around 13:1. But, the instant the value hits 10... the engine dies. I mean just plain cuts off. This may be a limitation of the ECM's hardware apparently. It's calculating BPW correctly, but it's subject to the resolution of the hardware then, the limitations of it as well.

This also explains why it just plain wouldn't idle in closed loop. It was hitting this same hardware wall when it was trimming back the AFR's as I have been trying to do.

I may need to look into a different injector management method. There is Async, and Quasi-Async. I'm not sure how that is going to play out. I may have to break out my 42.5's for the time being if I don't find a solution to my dilemma.

Bottom line, it does NOT like the 60 LB injectors. If I can't get it to shoot the right amount of fuel by one mean or another at an idle, then I will have to resort to changing injectors.

quote Originally posted by Fierobsessed: I think I've found my issue. The injectors MAY be too big after all. I sent L0089 to my data stream which is the LSB for the PWM sent to the Injector driver. It's the last value that gets sent to the injector driver to tell the hardware exactly what to do. It seems at idle, I was throwing out 18 counts, which was shooting 11.5:1 But then as I was lowering the idle VE table, slowly at first, I watched the number drop in decrements of 2. It would take around 4-5 whole % VE just to drop the counts a single decrement of 2. ONLY when this output value would change, I would see it affect the AFR's. This explains why the Idle VE table seemed to be numb to minor changes, but responsive to major ones. I could get the counts down to 12, and it would be shooting right around 13:1. But, the instant the value hits 10... the engine dies. I mean just plain cuts off. This may be a limitation of the ECM's hardware apparently. It's calculating BPW correctly, but it's subject to the resolution of the hardware then, the limitations of it as well. This also explains why it just plain wouldn't idle in closed loop. It was hitting this same hardware wall when it was trimming back the AFR's as I have been trying to do. I may need to look into a different injector management method. There is Async, and Quasi-Async. I'm not sure how that is going to play out. I may have to break out my 42.5's for the time being if I don't find a solution to my dilemma. Bottom line, it does NOT like the 60 LB injectors. If I can't get it to shoot the right amount of fuel by one mean or another at an idle, then I will have to resort to changing injectors.

Yep, all of that. You may still be okay by adjusting the two tables I mentioned as there are tune specifics for a stock motor and smaller injectors at play not to mention all the other stuff that a computer program is probably calculating the appropriate values for. There is also an injector spec sheet and I imagine yours is the same as mine which has flow specs for fuel pressure as low as the 30s. In other words you may need to drop your fuel pressure if you can. I removed the regulator along with enough outlet tubing from an 8100 V8 fuel rail which is adjustable and set my static fuel pressure to 40 psi which drops a little lower with idle vacuum.

This is why I often question members who plan to use injectors that appear to be far more than what they need as a "just in case I" approach. It's not a big deal until you decide you want to run closedloop. There is a member planning to use 80s on a 3800 SC right now with practical performance goals and that's a bit much for an intended daily driver.

I believe you can also select for single pulse at idle as well which I believe is tied to QUASI which you can disable to possibly get the desired effect.

[This message has been edited by Joseph Upson (edited 11-14-2013).]

increments of two sounds like you're already in single-fire mode, since the BPW calc is done assuming double-fire until BPW threshold is tested for, then doubled or cleared if single-fire conditions are met....

also, d10 = .153mSec.... that seems awfully short, even for 60lb/hr.

I guess I should really think about fuel pressure then! I'm not far from where I need to be, I just need that little bit less fuel, and of course a little breathing room. Realistically, I need something like 50 lb injectors for what I am doing. So a little less fuel pressure looks like my best option. I'm going to have to machine myself an adjustable, vacuum regulator. This sounds like a fun challenge!

[This message has been edited by Fierobsessed (edited 11-14-2013).]

I just read through this entire thread and i hope I'm not the only one who feels like they were just neutered.... yup i'm not a man after seeing this work wow man just wow I'm going to go outside and kick my fiero now lol

needless to say you did an amazing job and cudos on your talents sir.

take care
brian

quote Originally posted by Joseph Upson: I had trouble at idle with the 60s so I can imagine what you're probably going through with even less displacement, especially if you are running a base fuel pressure in the stock 50 psi range. It's very strange but yes there is something about attempting to run stoich AFR at idle that the motors do not like and usually it manifests with a rough idle although the rpm maybe stable. You basically need to give it what it wants until you find the balance as there appears to be some fine tuning fuel delivery that I don't believe the wideband can pick up but you can feel the difference.

This is due to mismatched dead times among your injectors. Most injector suppliers only match gross flow rate, but don't try to match dead times. Thus, the minimum fuel delivery per pulse can vary by 100% of the group average across the set.

If you're operating at minimum pulse width, one injector might be delivering 50% of the group average and the next might be delivering 150%... so one cylinder's always going to be lean (and misfiring) and one cylinder's always going to be rich, even though the average is stoich. To get the lean cylinder up to the point that it no longer misfires, the overall average has to be noticeably rich.

Injector Dynamics supplies injectors with matched dead times, but they're not cheap.

quote Originally posted by Will: This is due to mismatched dead times among your injectors. Most injector suppliers only match gross flow rate, but don't try to match dead times. Thus, the minimum fuel delivery per pulse can vary by 100% of the group average across the set. If you're operating at minimum pulse width, one injector might be delivering 50% of the group average and the next might be delivering 150%... so one cylinder's always going to be lean (and misfiring) and one cylinder's always going to be rich, even though the average is stoich. To get the lean cylinder up to the point that it no longer misfires, the overall average has to be noticeably rich. Injector Dynamics supplies injectors with matched dead times, but they're not cheap.

That's why I threw the idea of trying to relative-match the values on the injector spec sheet out the window, although my problem was with idle being too rich such as the case here. On the other hand, the two tables I mentioned when used together did help produce a more practical idle AFR without roughness and there is a gray area where the inj BPW offset table makes an audible difference when changed that can't be seen in the AFR reading. Both tables are a bit ratchetty regarding resolution but seem to work together well. RobertSaar mentioned the proportional gains tables but I found better response from the latter two. I do recall mention of the prop tables being of more significant help with radical camshafts on the Thirdgen forum.


You can look at the inj spec sheet and other specific data here in the thumbnails just below the main picture. Note the offset curve as system voltage drops. My fuel pump voltage runs about 1 volt below system/battery voltage and I was able to follow it and adjust the offset table accordingly by watching the AFR along with voltage drop as the alternator heated up.
http://www.siemensdeka.com/...114961/#!prettyPhoto

[This message has been edited by Joseph Upson (edited 11-19-2013).]

Yes, you DEFINITELY need to program dead time versus voltage into your computer in order to have the ECM trying to pulse the injectors correctly.

If you have full data logging capability of an OBDII computer, figuring out which injectors are doing what could be easier, as you can watch the misfire counters. If you try to idle at stoich and you're seeing #2 and #5 misfire a lot, then you move all the injectors to the next higher cylinder number (and 6 -> 1), then see #3 and #6 misfire counters go up... then you know which injectors are well outside the group average.

You can also log injector pulse width per cylinder on a sequential engine and back out the intake manifold correction if your samples are close enough in time.

[This message has been edited by Will (edited 11-19-2013).]

I'm not OBDII so that's not really something I can do much about.

In the meantime, I made an adjustable fuel pressure regulator... This was a fun challenge.
First, I found a spare fuel rail kicking around


This is the stock regulator


The obvious thing to do was to cut the top off, unconventional method, but effective!


Ok, so there is the spring, I need to make that adjustable.


Design time!


Chunk of stock


First I did the internal boring cuts


Then... I got so busy I didn't take many pictures.

Then This...




Assembled, I use a large snap ring to hold the two parts together.


Old vs new


Then, it was time to tear the upper intake manifold and the fuel rail off and put the custom regulator in


Regulator is in. Its quite a tight fit, a litte grinding was necessary to clear the lower intake manifold. But I knew it was going to be very tight.
I adjusted the unreferenced pressure to 34 PSI, put the intake manifold back on and went back to tuning. The pressure under idle vacuum was 28 PSI. That's pretty low. Theoretically it brings me to around 53 lb injectors.


I tried retuning it, and unfortunately its not enough. It will idle at 14.7:1 now which is great! but... it's still right at minimal pulse width. If I give it more timing like it wants, I have to pull some more fuel to idle, and it still dies. It looks like I'm going to have to break out the 42.5's weather or not I like it. I'm stuck with it for now. It's a bit disappointing. I'll up the fuel pressure back to 46, which was what the stock regulator was set at, run the 42.5's and run them to their maximum at whatever boost it will let me run. The only upside, is that I know this engine idles great at 14.7:1, but timing is a very conservative 16 degrees, the 3.4 DOHC wants more timing, and less fuel then this.

what is the PW? Have you tried single firing for idle?

Its firing between .12 and .15 ms to get me to 14.7:1.

I believe I am in single fire, but I have to check the logs.

Admittedly, it now idles and runs great at 14.7:1 open loop. But as soon as the slightest bit of fuel is trimmed by closed loop... it just shuts down.

I'm a bit curious though about idle timing. At idle I found if I start throwing a few degrees at it, the AFR's start to drop considerably even with the exact same amount of fuel going in. I assume that it's a good thing, its bringing up its idle fuel efficiency, and asking for fuel to be trimmed in return, which I am unable to do.

Is there an "every other revolution" mode? That might help... SFI works on that principal if I'm not mistaken. But it could cause instability I would guess.

I can't be the first to try to tune idle on a GM P4 ECM using 60 lb injectors. Makes me wonder what everyone else is doing, or what I am missing right now. These same injectors are used on some ULEV vehicles, so it has to be possible. Maybe the lack of SFI is the reason I can't get the PW's low enough to idle correctly. I can't fix that without rewiring the whole thing...

non-SFI shouldn't be a problem..... some of the code59 guys are running 80 lb/hr without issue IIRC.

i've forced single-fire mode in place of double-fire in A1 before..... i really didn't see a difference in terms of any output or idle stability or ......

but i was also playing with 3.1 liters and 16.7 lb/hr injectors, so i didn't have such critical of timings. i tried for a few weeks to try and get the transition from single-fire to double-fire correct, but i must not have understood the code that operates it well enough, roughly 50% of the time it would go off without a hitch.... the other times a calculated single-fire burst of fuel would have a double-fire burst of fuel added on top of it, causing the AFR to shoot way rich for a cycle. feels odd with the TCC locked. i seem to remember the double to single transition being less of a problem.

Did some code searching. looks like this code only sets the "Deliver fuel on every reference pulse" flag during cold start. I'm assuming that's 3 pulses per rev.

Otherwise, I can't find anything showing single or double fire mode anywhere.

quote Originally posted by Fierobsessed: Its firing between .12 and .15 ms to get me to 14.7:1. I believe I am in single fire, but I have to check the logs. Admittedly, it now idles and runs great at 14.7:1 open loop. But as soon as the slightest bit of fuel is trimmed by closed loop... it just shuts down. I'm a bit curious though about idle timing. At idle I found if I start throwing a few degrees at it, the AFR's start to drop considerably even with the exact same amount of fuel going in. I assume that it's a good thing, its bringing up its idle fuel efficiency, and asking for fuel to be trimmed in return, which I am unable to do. Is there an "every other revolution" mode? That might help... SFI works on that principal if I'm not mistaken. But it could cause instability I would guess. I can't be the first to try to tune idle on a GM P4 ECM using 60 lb injectors. Makes me wonder what everyone else is doing, or what I am missing right now. These same injectors are used on some ULEV vehicles, so it has to be possible. Maybe the lack of SFI is the reason I can't get the PW's low enough to idle correctly. I can't fix that without rewiring the whole thing...

Have you tried following the Integrator on the Tunerpro dash to see what it's doing at idle when closedloop is activated? It does not always match what the wideband reads. That helped me a lot with the direction I needed to go for adjustments as well as when loads were initiated at idle; cooling fan, A/C.

You may also need to start closedloop activation at a higher temperature for now, if it is as low as the 8F OE setting of ~80 deg. I had a fairly easy transition into closedloop at 135 deg and part of this problem is not knowing what all the coldstart tables are doing, when and for how long at startup to tune in consistency. Anything lower than 135 deg and an idle hunt set in along the way to full operating temp. So a coldstart areas state of tune varies as a result to the point of having a headache at a very low activation temp, to no trouble at a higher activation temp with such a large injector change.

You may also need to restore the characteristic idle spark advance for the tune, as well as find out what the typical idle spark advance is for that motor. When I zeroed out the idle spark correction tables a couple days ago as you had done, along with my already flattened sparkadvance area, I actually wound up with an idle hunt in openloop that I did not have with them in place before. So I reasoned that with my high compression ratio that perhaps I need to increase them a little above stock. So far so good although I'm still running openloop at the moment.

You may also need to consider your idle rpm setting considering the tune 8F anyway, was setup for a smaller motor with about 40 lbs of coverter, flywheel and fluid weight. I have the best results around 925 rpm. It may sound irrelevant but after wrestling with this subject for the better part of a year before making good progress you will want to consider all possibilities given the enormous number of tables in the code to accomplish the same thing "brainless" carbed engines did with little effort.

[This message has been edited by Joseph Upson (edited 11-20-2013).]

With more displacement and a lighter flywheel, the 3.4 will gain and lose RPM more quickly than the 3.1/auto. That affects idle stability significantly, as a given load will have a much larger effect on idle RPM and require a faster correction to keep the RPM from changing significantly.

i took a look at all stores to 3FD0.

the section of code starting at A4C3 looks to be the one involving single vs double-fire. there are two stores, A4F1 deals with the no-fire cycle, A528 deals with the double volume cycle(due to the LSLD at A501).

if single-fire isn't allowed, the code immediately jumps to A52E.

9.2.2 Quasi-Asynchronous Fuel Delivery
Quasi-Asynchronous fuel delivery is used when the synchronous fuel base pulse width becomes
so small that the fuel pulses cannot be accurately delivered.
Enabling quasi-asynchronous fuel mode will cause the fuel injectors to be energized every other
reference pulse but for twice the duration (of the normal synchronous base pulse width). This
results in the same amount of fuel being delivered, but with an accurately controllable injector
pulse width.

It looks like what I really need is quasi-asynchronous mode. Problem is, It's not activating it for some reason. It appears that all the conditions are being met, but it's not going into that mode.

C0D0, Battery voltage normal
C0DF, Engine running
C0E3, DFCO not active
C0F3, MPH not exceeding L86C2 (255)
C0F9, BPW high hysteresis qualifier L86BA (1.28 MSEC, I'm WELL BELOW!)
C102, BPW low hysteresis qualifier L86B8 (0.98 MSEC, Again, WAY BELOW)

So it should be setting the quasi async flag. but I'm not seeing it. I need to get this one figured out!

How About commanding 13:1 afr and see if it will idle that way. It should at least tell you if it's in the tune or injectors.

I would like to ask you a quick question that might help me with my build. I noticed you did not use the jackshaft intermediate axle that the F40 tranny uses, what application of inner cv cup are you using that will go into the F40 trans directly? I want to do my build without the jackshaft, but I haven't gotten to the axle research just yet.

Thanks, Mike