Thanks for the links! Although I already have a disassembly of the $8F code I always am looking for others thus to verify the information in my disassembly is correct. Thanks again!
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09:27 PM
Fierobsessed Member
Posts: 4782 From: Las Vegas, NV Registered: Dec 2001
Do you do your own dissassemblies? I'm really curious to know even just alittle about how there done. Notice there's a dissassembly for a 94-95. That could be some good stuff!
[This message has been edited by Fierobsessed (edited 10-19-2004).]
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09:51 PM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
Do you do your own dissassemblies? I'm really curious to know even just alittle about how there done. Notice there's a dissassembly for a 94-95. That could be some good stuff!
No, I don't do my own disassemblies. I have tried using a disassy program a couple of times but the ones I have just spit out addresses but don't tell what they are for nor if you are looking at a table or single constant. Yes, I noticed the $2E 94-95 3.4 DOHC SFI disassy and downloaded it. I also have an ECM editor program that goes along with my Tuner program so I could build my own tuning software for the 94-95 chip. The problem is this is time-intensive and I don't have one of these cars to do "testing" to make sure the changes I make to the chip will actually work. I wonder how many people would be interested in a custom chip for the 94-95 3.4 DOHC SFI computer and if it would be worth my while to put all the work into writing the tuning program for it?
I have a 96 3.4 DOHC that sooner or later will end up in my 5-sp 88 GT. As I understand it, following this thread, I am going to have a problem with the ERG valve using the 91-93 ECM. Will using the 94-95 ECM elimate the problem with the EGR valve? Is this the only diference between the two?
------------------ Ernie
1988 Silver GT One owner 47000 miles. Soon to be a 3.4 DOHC powered.
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02:00 PM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
I have a 96 3.4 DOHC that sooner or later will end up in my 5-sp 88 GT. As I understand it, following this thread, I am going to have a problem with the ERG valve using the 91-93 ECM. Will using the 94-95 ECM elimate the problem with the EGR valve? Is this the only diference between the two?
Dunno for sure, I haven't looked at the diagrams lately but as long as your 97 engine has the same EGR valve as the 94-95 engine, then there should not be any problems.
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02:13 PM
Oct 21st, 2004
gascarracer Member
Posts: 129 From: Batavia, Ohio, USA Registered: Apr 2003
No, I don't do my own disassemblies. I have tried using a disassy program a couple of times but the ones I have just spit out addresses but don't tell what they are for nor if you are looking at a table or single constant. Yes, I noticed the $2E 94-95 3.4 DOHC SFI disassy and downloaded it. I also have an ECM editor program that goes along with my Tuner program so I could build my own tuning software for the 94-95 chip. The problem is this is time-intensive and I don't have one of these cars to do "testing" to make sure the changes I make to the chip will actually work. I wonder how many people would be interested in a custom chip for the 94-95 3.4 DOHC SFI computer and if it would be worth my while to put all the work into writing the tuning program for it?
Darth Fiero
Let me try asking my question another way. What are the differences between a 91-93 and 94-95 ECM? I want to know which ECM is better before I can tell you which one I would be interested in.
------------------ Ernie
1988 Silver GT One owner 47000 miles. Soon to be a 3.4 DOHC powered.
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12:21 AM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
Let me try asking my question another way. What are the differences between a 91-93 and 94-95 ECM? I want to know which ECM is better before I can tell you which one I would be interested in.
Ok, well first off the 94-95 PCM has SFI and uses a MAF sensor. A MAF sensor is able to more easily compensate for mods done to a stock engine. However it should be noted that there are limitations to what the MAF can compensate for, these limitations are set in the chip. The 94-95 PCM also has more wiring involved and does not have a factory chip compatible with a manual trans. There is currently no programming out for these systems, although I am currently doing some "beta" testing on my own programming for these.
The 91-93 PCM's are speed density and batch fire fuel injection. Speed density means they use a MAP sensor and have less of an ability to compensate for mod changes to the engine. However there is extensive programming support available for this computer and I do have both the 4T60-E and 5-speed manual programs on file.
Differences between SFI and Batch Fire: SFI fires the injectors sequentually, at least at engine speeds up to about 3000rpm. Most SFI systems go into batch fire mode at engine speeds above 3000rpm due to the very short time between cylinder firing events. Thus any advantage of having SFI over batch fire is null above 3000rpm. Supposidly SFI systems offer slightly better idle quality and gas mileage compared to batch fire. While I have found this to be true for the most part, these differences are very very small.
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12:34 AM
gascarracer Member
Posts: 129 From: Batavia, Ohio, USA Registered: Apr 2003
Thanks for both of your speedy replys of my questions. I have enjoyed following this thread and it has a lot of good information on the swap. I really appreciate the time and energy you have devoted to this thread. Thanks
------------------ Ernie
1988 Silver GT One owner 47000 miles. Soon to be a 3.4 DOHC powered.
I am doing a 3.4 DOHC swap right now and have run into a few hang ups. 1. I have two brown wires out of the harness that are for the alternator but the alternator plug only has one red wire coming out of it. 2. Also i have two ignition wires from the harness. One in pink and the other orange and i have no idea where to hook them up to fiero. 3. Does the main power feed go directly from the alternator to the battery?
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06:13 PM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
I am doing a 3.4 DOHC swap right now and have run into a few hang ups. 1. I have two brown wires out of the harness that are for the alternator but the alternator plug only has one red wire coming out of it. 2. Also i have two ignition wires from the harness. One in pink and the other orange and i have no idea where to hook them up to fiero. 3. Does the main power feed go directly from the alternator to the battery?
The single wire coming from the alternator connector should be small (16-18 gauge) and it gets connected to the Fiero's brown alternator wire that hooks into TERM B3 of the C500 connector.
All ignition power wires in the harness should be Pink, Pink with Black stripe, or Brown in color. Usually the Orange wire is constant B+. Verify by doing a continuity test using a DVOM and wiring diagrams.
The stud/nut on the back of the alternator gets connected to the power distribution block by the Fiero C500 connector, or you can connect it directly to the battery. Make sure there is a fusible link on this wire in case the diodes in the alternator short out.
------------------ power corrupts. absolute power corrupts absolutely. Custom Chip Burning | Fiero Engine Conversions | Turbocharging | www.gmtuners.com
hmm random thought - but using the grandprix alternator rather than the fiero alternator won't complicate things right?
and can I use the r134 AC compressor instead of the fiero unit.. will it work ok? I'm sure i need to replace something up front to make the pressures correct.
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08:08 AM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
hmm random thought - but using the grandprix alternator rather than the fiero alternator won't complicate things right?
and can I use the r134 AC compressor instead of the fiero unit.. will it work ok? I'm sure i need to replace something up front to make the pressures correct.
Trying to use a stock Fiero alternator on the 3.4 DOHC engine will complicate things because it won't bolt up. You will need the GP alternator. The only issue you might run into is the wiring for the alternator, specifically the connector styles might be different.
As far as the A/C compressor you might be able to use the stock Fiero compressor but you will have to change the pulley. By the time you find a pulley and change it I think you would be better off to use the newer DOHC a/c compressor that comes on the engine. If you are thinking of switching to R-134a at this time I recommend a 94-up compressor that is already set up to run R-134a, the performance will be better. You may have to get custom A/C lines made but some people have commented they were able to use the stockers with some "mild bending" of the lines. I didn't try bending the stockers because I have a source for custom a/c lines cheap which means I get new rubber hose as well. Stock Fiero hose is not set up for 134a and according to the A/C community you have a 50/50 shot they could leak.
ok another question - what is the stock thermostat temp?
would it be beneficial to lower the temp if it will see a turbo in the future?
Stock thermostat temp is 195. I wouldn't go any lower than a 180 stat on an engine using stock internals. A turbo engine would benefit some from the 180 thermostat. Also a 180 stat would probably give you a little more power out of a n/a engine but would still give you good heat in the winter.
Darth (and/or anyone else with extensive DOHC experience),
I've got the bug again to begin work on my conversion and have a few questions. I'm hoping you can help:
- Can you program the chip to eliminate the EGR?
- If I eliminate the EGR, can I also eliminate the air pump?
- I want to eliminate the throttle body pre-heater. Can I just tap and plug the water passages?
- I have a chip out of a 3.1. Can you use reprogram it to work with my 3.4 5-speed?
Thanks in advance, Roy
Roy, I can do a chip no problem to eliminate EGR and AIR functions. As far as the chip you have, what computer did it come out of (service number)? As long as it came out of a 16149396 ECM it will work no problem. As far as the throttle body "pre-heater", you cannot disable it. On the 3.4 DOHC this coolant passage serves as the water pump bypass and if you plug it you will build excess pressure in the heater core coolant circuit whenever the thermostat is closed. There is no way to re-route this circuit because the coolant flow supply comes out of the top of the lower intake and passes into the upper plenum directly, this is that O-ring seal that goes between the two. I suppose if you really wanted to you could find some way of doing an external bypass but it is an aweful lot of work for something that is not going to cost you any measurable performance loss if you just leave it stock.
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08:39 PM
PFF
System Bot
Nov 24th, 2004
mrfixit58 Member
Posts: 3330 From: Seffner, Fl, USA Registered: Jul 99
I'll check the ECM number and let you know. Do you think that, I eliminate the AIR pump, I'll need to install another idler pully in it's place? I appreciate the advise on the throttle body pre-heater, your point is well taken. I wasn't actually too concerned about the change in performance by eliminating the pre-heater as I was more interested in reducing the number of pipes and hoses I had to deal with.
Thanks again, Roy
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07:56 AM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
I'll check the ECM number and let you know. Do you think that, I eliminate the AIR pump, I'll need to install another idler pully in it's place? I appreciate the advise on the throttle body pre-heater, your point is well taken. I wasn't actually too concerned about the change in performance by eliminating the pre-heater as I was more interested in reducing the number of pipes and hoses I had to deal with.
Thanks again, Roy
Roy, according to my information, all AIR pumps used with the 3.4 DOHC engines were electical, so there will be no idler pulley needed if you remove them.
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12:29 PM
mrfixit58 Member
Posts: 3330 From: Seffner, Fl, USA Registered: Jul 99
Boy... Do I feel stupid. During my lunch break I took a closer look at my motor and realized that I was looking at the water pump. It looks just like an old GM AIR pump. As it turns out, I don't have an AIR pump. I pulled the motor from an 95 and the wiring harness out of a 93. Thanks for helping me clear that issue up.
I also checked my ECM and confirmed it is a 16149396. Please send me a PM or email and let me know where to send the chip and the check.
Thanks again, Roy
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02:06 PM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
Boy... Do I feel stupid. During my lunch break I took a closer look at my motor and realized that I was looking at the water pump. It looks just like an old GM AIR pump. As it turns out, I don't have an AIR pump. I pulled the motor from an 95 and the wiring harness out of a 93. Thanks for helping me clear that issue up.
I also checked my ECM and confirmed it is a 16149396. Please send me a PM or email and let me know where to send the chip and the check.
Thanks again, Roy
you have mail
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02:35 PM
soloyosh Member
Posts: 192 From: Queen Creek, AZ Registered: Jun 2003
Originally posted by Darth Fiero: I wonder how many people would be interested in a custom chip for the 94-95 3.4 DOHC SFI computer and if it would be worth my while to put all the work into writing the tuning program for it?
I AM INTERESTED!
Just bought an ECM from a local yard (16196401), got a lead on a harness.
------------------ Brett 1988 Fiero 1988 Fiero Formula
[This message has been edited by soloyosh (edited 11-24-2004).]
getting ready to start diggin into mine - is it easiest to start with the tdc harness and remove unwanted items? or start with a v6 fiero harness and change any connectors and add wires?
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08:19 AM
Darth Fiero Member
Posts: 5921 From: Waterloo, Indiana Registered: Oct 2002
getting ready to start diggin into mine - is it easiest to start with the tdc harness and remove unwanted items? or start with a v6 fiero harness and change any connectors and add wires?
Actually I recommend you start with a Fiero 2.8 harness and just change the computer connectors and then lengthen/shorten the engine harness components as neccessary. I think the only wiring in the engine harness that did not need to be modified was for the MAP sensor. Of course I did all this work so the swap would look better than a factory install. You will have to add a wire or two for the EVAP solenoid and the Knock Sensor and possibly one for the EGR if you are using it. But other than that the stock 2.8 harness has nearly everything you need. Of course some connectors are different.
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02:02 PM
Feb 4th, 2005
newfierokid Member
Posts: 278 From: largo,FL, USA Registered: Feb 2004
I couldn't find it anywhere but did you use the stock serpentine belt? or did you have to get a different length?
If I remember correctly I was able to use the stock length serp belt, but I am not 100% sure. Best thing to do is put a stocker on and see if the tensioner is at the end of its travel (loose). If not, you should be good to go.
Excellent piece you made there by the way for the pulley spacer.
ok another question - how did you route the heater core lines?
i know that in 87 they removed the trunk wall line and had it branching off of the passenger side coolant line
but on an 84-86 where there is a heater core line on the firewall.. what would be a good way to route them ?
I could put a T section in the passenger coolant line and remove the trunk line..
but then what about the heater core line on the TDC thak comes out of the throttle body.. can I just remove the throttle body lines and plug the line that comes off the TDC thermostat housing?
working ont he logistics of whats left for me to complete the swap
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06:17 PM
Erik Member
Posts: 5625 From: Des Moines, Iowa Registered: Jul 2002
My 88 coupe has the tee on the passenger side coolant line so basically all you have to do if yours is like mine is run one line to the intake right below the throttle body. Mine has the one line that runs along the passenger side lower frame rail and all I did was run an extended length of hose off of it to reach the fitting on the intake
[This message has been edited by Erik (edited 02-25-2005).]
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06:32 PM
Erik Member
Posts: 5625 From: Des Moines, Iowa Registered: Jul 2002
My 88 coupe has the tee on the passenger side coolant line so basically all you have to do if yours is like mine is run one line to the intake right below the throttle body. Mine has the one line that runs along the passenger side lower frame rail and all I did was run an extended length of hose off of it to reach the fitting on the intake
is that what you did? or can I remove that small line that runs to the throttle body?
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09:03 PM
Erik Member
Posts: 5625 From: Des Moines, Iowa Registered: Jul 2002
Here is my configuration. There is a length of heaterhose added to the end of the stock flexible hose nipple and runs along the backside of the engine bay firewall. I suppose you could run part of it as a hardline but mine is all flexible heaterhose secured to the backside firewall and curves up to the intake nipple
I would leave the line running from the intake to the waterpump indicated in the picture as a black line. Its there in part to warm the throttlebody and works as like a bypass to recirculate water from the heads back to the waterpump while the thermo is closed, for anti waterpump cavitation purposes at high rpm as well as to keep airpockets from hanging out in the top of the heads coolant passages. Plus it keeps too much pressure from being applied to the heatercore while the thermo is closed. I would of course plug up any extra ports at the waterpump with brass pipe plugs of the proper size
[This message has been edited by Erik (edited 03-04-2005).]
