Having fought with this swap I am down to one problem that I can't figure out. I set the VATS to none with HPtuners and turn off the related DTC's. The first time after writing the tune to the ECM the engine starts and runs. Turn the key off and try to restart and no injector pulses. Set the VATS to Serial the engine does the same thing. No DTC codes, but when I look at the injectors with HPtuners they are all disabled and I can not change their state. Does anyone have any ideas?
Thanks Joe Sokol
------------------ 85 SE Daily driver with a 3.4 DOHC OBD II 88 Formula/GT 4.9 Allante Intake (My Baby) www.fieroking.com
Are you sure HP Tuners will actually turn off VATS on that ECM? This is a Series 3 swap retaining DBW and there have been some known issues making everthing work.
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Originally posted by Darth Fiero:
All 3800 Series 3 engines use drive-by-wire (DBW) throttle bodies.
Most 3800 Series 2 engines use cable-op throttle bodies, with a very few exceptions (notably: 99-02 F-body).
The problem with the DBW PCMs involves an issue in being able to turn off certain abuse modes in the tune in order to prevent the PCM from "shutting down" the throttle if you try to floor it from a dead stop. I've run into this several times on swaps using Series 3 DBW PCMs and could not correct it with the tuning software I had available at the time that works with these PCMs (HP Tuners). It has been several years since I've tried to tune any Series 3 PCM for a swap so I do not know if HP Tuners added an option to disable whatever function was causing the engine power limiting at take off issue. Another issue with Series 3 PCMs is VATS, and last time I messed with one HP Tuner's was not able to disable it in the tune (again, that was several years ago).
Converting a Series 3 engine over to use a cable-op throttle body (and earlier PCM) is not difficult. All you need is an adapter plate, throttle body, and the older harness and computer. If you are using a 4T65-E trans that came with the Series 3 engine, then you will need to use a 2003-05 Series 2 PCM when converting to cable-op TB control. 2002-older PCMs will not work with a 2003-newer 4T65-E because of electrical changes GM made to these transmissions starting in the 2003 model year.
I recommend to all my tuning customers to convert a Series 3 over to cable-op TB control for engine swap purposes so the inherent problems associated with the use of the Series 3 PCM can be avoided.
Again, I have not attempted to tune a Series 3 PCM in a few years for a swap so I do not know if HP Tuners added options that would be able to disable VATS and the "take-off power limiter" in these PCMs. Last I read, HP Tuners said they were no longer doing any development work on ANY 3800 applications because they claim it is a "dead end".
I am able (I think) to turn off and on the VATS with HP tuners I can also turn off the codes related to the VATS. It is so odd that when I load a full tune with the VATS on or off that the engine runs until I turn off the key then the next try to start on injector pulses.
Joe Sokol
------------------ 85 SE Daily driver with a 3.4 DOHC OBD II 88 Formula/GT 4.9 Allante Intake (My Baby) www.fieroking.com
Forum member Jncomutt currently has a Fiero for sale in the mall with a 3800SC series III engine swap that is running in DBW mode. Send him a PM and ask about how he did his program. I believe the guys name is John. When I did my 2006 3800SC series III swap we converted to a cable operated TB ( N*) , LS1 MAF sensor and used the 03 GTP PCM for engine management. It wasn't hard to disable the VATS. Used series II engine management as it avoids the traction control interface that the series III PCM is expecting to see. A number of series III DBW swaps have been done on Fieros over the years and most of them were documented here. .
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 03-17-2020).]
Dennis is correct, I am using a DBW setup on a S3 swap.
I was under the impression that 04, 05, 06, 07 setups had different PCMs despite having S3/DBW. I could be wrong, I'm not sure, and I'm not sure what years the different PCMs apply to.
With that said, you must do a full rewrite on these pcm, not a partial. Try that and report back. I can check my tune when I'm home this evening. Also, the PCM connectors are very finicky. Remove each of the 3 connectors and check them with a flashlight. Be SURE all the pins are flush to the face of the connector. Make sure you are using the back caps to the connectors, and make sure the harness is pushed towards the connector, and zip tied in place to the existing strain relief.
Is this the same PCM?
[This message has been edited by Jncomutt (edited 03-20-2020).]
The ECM looks the same. My problem is that When I do a Write Entire to the ECM with the VATS turned off with HPtuners the engine will start and run normally and all the values look good with the VCM scanner. However when the engine is turned off and you attempt to restart it there are no injector pulses and looking at the injectors with VCM scanned shows all the injectors disabled. When I do another write to the ECM with the VATS turned on the engine runs and when the engine is turned off and you attempt to restart it there are no injector pulses and looking at the injectors with VCM scanned shows all the injectors disabled. I have gone through the DTC's and turned off everything to do with the VATS in both conditions, I just can not figure out why the engine only runs one time?
Thanks for your help Joe Sokol
------------------ 85 SE Daily driver with a 3.4 DOHC OBD II 88 Formula/GT 4.9 Allante Intake (My Baby) www.fieroking.com
I just pulled up my tune file, my VATS is set to "NONE". My operating system is 12610181.
Try pressing the throttle pedal a little bit to see you are getting fuel pulses. Are the fuel pulses staying off, or is it just a delay, leading to a long crank, but an eventual start?
Interesting new information. If the battery is disconnected for about 5 minutes the car starts and stays running. If it is turned off then we try to restart it just cranks.
Joe Sokol
------------------ 85 SE Daily driver with a 3.4 DOHC OBD II 88 Formula/GT 4.9 Allante Intake (My Baby) www.fieroking.com
It may make sense to ask what PCM # Jncomutt is using, then try the VATS turn off on that. If all else fails; is there not a way of using a signal generator to supply the missing ignition circuit turn on signal?
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
