Any updates? Im interested in knowing what kind of fuel economy and performance your getting......

Mike

Funny you should ask. I just finished my first tank of gas. This one I could not keep my foot out of the floor since it was so fun feeling the power. It was mostly around town driving and a little hwy to my house.
Combined I got 22.5mpg which I thought was not bad at all with all the rodding I was doing. I even raced another import two seater think it was a Taco Del Sol, not sure. (to dark) Waxed him good.

This tank I'm going to take it easy and see what happens.

[This message has been edited by Dodgerunner (edited 03-30-2007).]

quote Originally posted by Dodgerunner: Funny you should ask. I just finished my first tank of gas. This one I could not keep my foot out of the floor since it was so fun feeling the power. It was mostly around town driving and a little hwy to my house. Combined I got 22.5mpg which I thought was not bad at all with all the rodding I was doing. I even raced another import two seater but not sure yet what it was. Waxed him good.

Hhmmm, And this was originally being built just as a daily driver --to and from work for economical reasons?? And the Wife bought it hook line and sinker....hehehehe I wonder how economical a NorthStar is going to be when you start it..lol...

3800sc maybe but not a v8 that would be Sacrilegious to the Fiero Gods.

The biggest problem with the 3.4 swap is the limited air delivery. Even the stock 3.4 intake is small for the job, the fiero intake is really limp. You should consider porting it and adding an air box to the upper plenum. Otherwise, looks great!

Dodgerunner, are you running a modified chip?

No running the stock 85 chip. ALDL looks good as far as INT and BLM. Might be a little rich on idle but crusing it controls very well. (running the camaro injectors.)

Maybe you don't care department...

The 3.4 is running great. Maybe a slight lifter noise from them being adjusted a little light but not bad. The 2.8's seem to always have some rocker noise don't they?

So far I'm running about 23-23 mpg in town driving. I have not done any HWY driving other than the 3 miles to the house.

Next projects are front bushing replacement, door rebuild, and paint the car GM Bright White.

Also have noticed some hesitation just off idle. Think it might be related to the 3.4 injectors being a little rich at idle.
Will make some logs and start to tweak the prom to see if I can work that out.

It does help with quick launches. Had a little run with an 89 firebird the other morning. Noooo problem, course he probabaly just had a 305.

[This message has been edited by Dodgerunner (edited 03-30-2007).]

quote Originally posted by sardonyx247: I have the 5sp Getrag. The best MPG would be to use the 4sp eco I would think. But it is slow. You can even get a MPG gauge to help max it out. Which is just a vac gauge relabeled.

FWIW, the overall gearing in top gear with the Isuzu is 2.48; the econo 4 speed is 2.42 Not enought to make a difference here. Slghtly larger tires would probably make up for this difference.

Did you use the Isuzu T/O bearing?

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FierOmar

Welll mpg still running around 24. (intown driving)

Logged some data today and the blm is running a solid 120 and the int runs a little below 128 most of the time.

Tomorrow going to bump the BPW down a little and see if it will bring the blm up a little.

[This message has been edited by Dodgerunner (edited 12-31-2007).]

What are you using to tune the car? Software and hardware wise?

The old trusty prom burner and GMPro software. (have since switched to Tunercat) First time doing it, will burn a spare prom and then compare the orig. and new to make sure the right changes where made.

Was going to start by changing the BASE PLUS VE VS RPM and see what the results of a test run are then move to the rpm/map table.

[This message has been edited by Dodgerunner (edited 12-31-2007).]

Have had a couple members ask for dimenions of my gantry so did a quick drawing.

[This message has been edited by Dodgerunner (edited 04-13-2007).]

how bad is the hesatation off the line?? think running rich will foul out the plugs quickly??..im doing a 3400 swap with using the same setup you have (fiero upper end) and i was also wondering how mine would run with the bigger injectors, stock cpu and chip but mines an 88 and i dont know if 88 cpu's are diff or not.

bump otherwise

Sorry missed you post before now.

Mine run really well off the line even being somewhat rich. Is very quick and never felt bogged down from being richer. In fact felt like a rocket. 0-60 was 4-4.5 sec. if I didn't miss a shift.
I don't think the 88 ecm would be any different, your still swapping for a 2.8 either way and how much could really change.

I have since been tweaking the eprom leaning out the table and adjusting timing to reduce the higher rpm/high load knock that all the 3.4's seem to have from the swap. I'm gaining on the knock.

One of the improvements that have come out of leaning the table is that the engine is much smoother in shifts. Before I started changing the fuel table is seemed the rpms dropped to fast and shifting from 1-2-3 where harder to make smooth without playing the gas more. After adjusting the fuel table I noticed a difference right away.

Still working of getting the idle leaned out more right now and have a little knock left around 40-50 Kpa and 2500-3000 rpm.

[This message has been edited by Dodgerunner (edited 04-25-2007).]

do you think that you will be able to get it perfect? or will it always be off one way or another?.....AND you do know that if you work it out right then your going to be a target! lol im already itching to mail you my cpu lol...but my 3400 is still a day or so from starting up, so i wont know till then if its going to have the fuel problem or not??? can 91octane or retarding the timeing a little bit help??...quite honestly my 2.8 knocked at load in highway speeds, like tring to accelerate (auto trans) from 65 to 80mph not flooring it but just taking it easy it knocks there...with use of 91 octane it went away...i dont know what that was all about but its weird, so your my reliable buddy for this saga lol..the only (seems to be) knowlegable sane person that knows whats going on here lol. so if you get your right will it be really easy to reprogram other cpu's? or still a roya pita?

Well getting the knock out is fairly easy. Just need to reduce the advance in the right cells. I'm gaining on that, however the idle hunting is more of a challenge. Thought I was getting closer but then the air temp changes from day to day and it acts different. Right now I gain up to the current air temp and then the days get warmer and it shows up again. Need to figure out what values affect idle fuel and air temp. There are a couple tables but not sure which is the right one to do.

Always like a challenge....

good luck man!!! like i said in like tomorrow il have my running 3400 and il be in that boat also..so keep it comming!

I solved my erratic idle with a change to the 1227730 ECM and DIS. Even with the stock '88 Beretta mem-cal, the car idles rock steady. As it goes into closed loop, it idles down from 1100 to 900, the a/f ratio comes down from about 11:1 to 14.7:1, still a nice steady idle. Now I'm not sure if it is the ECM or the DIS that helped since I changed both at the same time.

Dodgerunner, you have another distributor that you could try to see if its maybe related? Did you rebuild your distributor when you put in that engine?

I took the Dist apart and cleaned but did not replace the pickup or module (looked good). Cap and rotor are new but that is it.
There is no wear in the shaft bushing. Have my 88 (50K) I could swap the Dist out of just to see what effect that has on it.

I have spare module and pickup I could also try.

Where is the distributor? Oh noooooo

Now your just having to much fun!

my 3400 started today!!!...but it ticks.........read other 3400 YABT post to see y

Well been driving the 85GT to work when it's dry weather. It's 20 miles round trip little Hwy and mostly in town.

Been getting 24.? MPG no matter how I drive it.

Just did my first trip all Hwy driving. 180 miles on one tank. Filled up before I left and filled up at the same pump when I got back. I was hoping for 29-30 mpg. Well seem to good to be true but got just over 35 mpg on E10 89 oct.

All the roads where 60 or 65 mph roads.

Lets just say I'm VERY pleased that the 3.4 did this, hope it continues to hold true.

Now if I get the rich idle adjusted maybe the in town mileage will improve also.

[This message has been edited by Dodgerunner (edited 05-12-2007).]

I'm very interested in doing this also. I assume this swap really woke up the car compared to the 2.8L.
Since the Fiero is my daily toy, I don't wan't to do extreme things. Just a little more power of the line with still getting about the same mpg like the 2.8L.
There is a 3.4L near from a smashed '94 Firebird, 5speed, with 42k miles on it.
Well I think I have to talk to my mechanicien...

Looking forward to more infos about the daily use!

i wish i could add to the daily use of mine...but its still in the shop after the 2nd rocker arm came off, the guy wanted me to order stock rocker arm bolts..ordered them last monday..told they would be here tuesday morning...checked everyday and still not there..really poed me off! so its still there and not running well.

Ok just thought I would update again. The latest version of eprom for the 3.4 I worked on the idle area.
I have the hunting idle when the engine is hot and I am stopped at a light.

I also tweaked a few of the rich upper areas after the last couple winaldl logs.

Made a trip to Omaha to check out the Upullit for anything new. Bust trip ! Did pull a couple more small Grand Prix headlights for my headlight mod I'm starting on.

Anyway when stopped at lights the idle would do one bounce and then settle right in at 900 rpm. I know the idle was running really rich and was hoping correcting the fuel would help the idle hunt. So far is looking good.

Also mpg on the round trip was 37.4mpg even with the wind blowing me all over the road. I'm liking this 3.4 better all the time. Wish I could get a 5sp in and see what difference that might make. Don't like the revs on the interstate so I kept it under 70 most of the time.
Wonder what that G6 6sp would do....................

Still have some knocking under accel. Will keep working on that.

[This message has been edited by Dodgerunner (edited 05-19-2007).]

SOOO whats your update??? get the ecm all panned out???..my big question is how in the world did you get 37mpg?!!? lol thats WAY impressive! you are using a 4speed tranny right? the first gear in a 4 speed is more agressive than the th125 right? so you can burn off some tires if you stopmed it from a get go?..

mines not doing so well, runs great i mean i just got the spark knock figured out, just slapped in some really cold plugs and ran 93 octane with no ethonal, it still pings a little bit but not bad, i do have to retard the timeing on the highway tho, sounds like im dragging 100 tin cans behind me if i dont, so that sucks, and i think having to retard the timeing may be giving me bad HWY millage..i think im getting like 23 hwy and 14city with the th125 + i still have that horrid knock sound...which i lean towards exhaust leak more and more everyday.

I'm not sure how I lucked out on the mpg. Yes have the stock 4sp with syncro lube.
The biggest thing I can think of is porting the heads, logs and Y pipe. Maybe just letting it breath easier makes a lot of differnce.
Someone said it would not do that good but what can I say. I get a consistant 24mpg driving to work across town. (which in Lincoln Ne is no big deal since it's not like a big city 11 stop signs and lights in the 10 miles between the house and work)
Have made 6 trips between Omaha and Lincoln allowing me to check the mileage easily and am getting 37 all the time. (100 miles round trip.)

Believe the porting helped the power also. I can break the tires loose in second a bit on the hwy. But ya 1st is very low so you can burn them good there.

I'm still weaking the eprom. Still not satisfied and want idle a little leaner. I'm still runing E10 all the time and only pings when the engine is at op temp and lower rpms.

Going to start sanding this week to prep for painting.

Dodgerunner do you post on any of the local websites? Gmmodernmuscle.com or nestreetscene.com?
I'm from omaha and I will be swapping a 3.4 into my 87 Zimmer Quicksilver when i get back. 1st time I have fooled with anything fiero wise. I have an 87 4banger that I use for a beater that I am going to cannibilise for its cradle and many other parts. I hit up u-pull it every blue moon, at the place next to u-pullit south there were 2 blue fieros not too long ago.

[This message has been edited by Zimmer (edited 09-10-2007).]

quote Originally posted by Dodgerunner: The old trusty prom burner and GMPro software. First time doing it, will burn a spare prom and then compare the orig. and new to make sure the right changes where made. Was going to start by changing the BASE PLUS VE VS RPM and see what the results of a test run are then move to the rpm/map table.

Are you willing to share a bin file when you get a good tune? I know it wont be a drop in and work solution, but it will help in seeing what changes you had to make and give great insight as to the differences between the 2.8 and 3.4 ot the fiero ECM.

I be glad to share the bin and/or list what I changed from the stock 85 prom.....

As I said, I'm satified with the mid to top end, but the idle is still somewhat rich. I believe it might be partly from the porting and maybe the cam so don't know if I'll get all of it out or not.

Also have to see how it reacts to cold weather since I removed the TB heat lines.

DR

so you can get it to bark tires in 2nd??! thats pretty nice, but im sure 2nd gear on the 4sped is like 1st gear on a 125c, mine will only bark a little on take off but with the 125 trans and 225's tires im not suprised..which is also prolly why my mpg sucks so bad! im running 3,700rpm at 75mph...im jelous il just come out and say it .lol...i want a 4speed auto!

if you could email it to me? timgray1@gmail.com

Thanks a ton!

Also, why did you go with the 85ECM? just what was in the car or are you planning on using that knock sensor input?

[This message has been edited by timgray (edited 09-10-2007).]

Are you using a 2.8 ECM?

Yes I'm using my 85 ECM but I have made a lot of changes in the stock prom to lean out the idle, improve cold start, and am working to see if I can reduce the times when the idle hunts.

[This message has been edited by Dodgerunner (edited 12-31-2007).]

bump for an interesting thread...

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quote Originally posted by 1MohrFiero: bump for an interesting thread...

Hey, thanks for bumping this up. I just read the whole thread, good stuff here.

I was particularly impressed with the injector flow test rig that Dodgerunner built, the gantry was good stuff too.

is there any possible way you can put all thses pics on a cd and send me a copy, my computer is kinda slow and i'm going to do this to my car soon, and these pics would be very helpful, let me know,thanks AL.

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[This message has been edited by AL (edited 02-24-2008).]

Bump for fun. Added new bike picture on page one, note at top of page.