3400 stalling after swap

[FieroGT]

Hey all, for the most part i got the 3400 running well in my Fiero. i'm using the 1227730 ecm out of a 93 corsica. but i've been having a prob where most of the time i push in the clutch to come to a stop, the engine stalls. mostly after i've been in gear slowing down with no gas pedal applied. its like the stinkin iac aint opening fast enough to keep it from stalling. i wonder could this problem be cuz i'm using ecm code for an automatic? i've tried playing with the tps to 'fool' the puter into thinkin differently, like more gas , which does prevent it from stalling, but then the idle is way to high. any thoughts?

[Anonymous]

Hey I thought only 3.4 DOHCs did this, WOOHOO

[brian89gp]

Re: 3400 stalling after swap

. i wonder could this problem be cuz i'm using ecm code for an automatic?

If you have anyting other then an automatic then yes. Find a chip made for a 5spd and either move all the related settings over or tune it for the 3400.

[FieroGT]

hmm, welp, then does anyone here happen to have a chip with 5-speed code on it? or can someone reprogram my chip with a new code CHEAP? or for trade... dont really have any $$ now, and i gotta get this thing running right.

[Mechanic]

The Fiero 5-spd 282 Getrag VSS sensor differs from the one used on the 3.1 VIN T platforms, so no matter what "stock" code you use it will still cause the stalling problem.  Requires a simple change to the "Road Speed Sensor Constant" so that the PCM will see correct vehicle speed. (The instrument panel speedometer speed and the PCM vehicle speed are two different entities.)
There are also various other issues that are not readily apparent when the PCM's VSS calibration is out of whack.

[pontiacjeff]

Mick and the Mechanics!

[x-thumpr-x]

Hmmm.. I've been getting the same situation with my fiero. Every now and then it likes to stall on me, especially on warm-up.

How the the ecm programming read it differently? I'm using an ecm from a cav 3.1L. It uses 4000pluse/min same as the fiero cluster speedo. I have the ecm and cluster paralled right now and it runs fine just for the ocasional stall.

Also, like to learn more about you turbo Mechanic..your link in the sig isn't working.

[Mechanic]

The Fiero Getrag uses a gear driven magnetic sensor, while the 3.1L FWD code expects to see the pulse from an optical sensor. The pulses per mile from the two different sensors differ greatly. It is the vehicle speed that the PCM uses that is important here, not the speed shown at the instrument panel. You need an ALDL scanning setup of some type to monitor and adjust this value correctly. The "VSS - Road Speed Sensor Constant" is changed to "recalibrate" for the different sensor.
I believe some versions of the $A1.pcm file even contain notes that indicate the correct hex value to use for the road speed sensor constant in this situation.

The GMPCM websites servers have been undergoing some major hardware related changes lately. If you do recieve an error, I appoligize, and ask that you try again at a later time.