94 Trans Sport 3.8 no power, stalls...

[96tsport]

Originally Posted by scottd60

Installed new TPS and O2...seems to be running pretty good again...still getting the Quad Driver Module codes P0640 & P0670...can't figure out what they are?

fwiw ..don't have a PO670 code showing in Haynes & a quick google of 'gm (or pontiac) code PO670' brings up Glow Plug Module Control Circuit..

Haynes also shows PO650 (no PO640) for Quad Driver Module Circuit.

[Jeffrv]

I didn't realize 94 was OBD II compliant as well, as 95 models. The following applies to 95 model but I suspect may very well apply to your 94. Code 1640 is QDM #1 fault, and the manual states the following symptoms:
TCC inoperative
rough or high idel due to evap purge solenoid being "on" all the time.
This driver permits the PCM to allow higher current devices ( solenoids ) to be controlled by the pcm. Power is supplied to the circuits from the hot key side, and is grounded through the pcm. Check for shorts on the dark green/white wire from the evap solenoid ( located on a bracket located on the rear on the engine just beind the fuel injectors) or the tan/black wire on the TTC apply solenoid loacted inside the transaxle. If it were to be shorted to ground the tcc will be contastantly trying to engage, and will result in sluggish performance.
Code P1670 is QDM # 4 fault, and controls A/C relay, and pusher and puller fan relays. You say you have AC problems, again check the dark green/white wire off the ac relay for shorts or opens.
The evap canister solenoid problem is emission related and could be the reason for your failure in testing. Check for 12V at the solenoid, it should be cycling but I suspect it is staying on, allowing lots of air into the engine, hence the high idle. However, tha manual also goes on that is there is no short to ground in the circuit, replace the pcm.
Good luck
Jeff

[Jrs3800]

The 94-95 3800 Powered U Bodies are not OBD2 compliant... They are full on OBD1 but they use OBD2 codes... These PCM's were the step before GM went to OBD2 in 1996.. So its sort of a mixed computer..

But with the code presented, do as the poster above has stated... The PCM is seeing an issue with one of the items on that circuit