Engine surging/stalling SES light.

[90corsicaLTZ]

My G/f's car is a 1990 Corsica LTZ, 3.1 V6 auto. The beginning of June we drove both ways on a 7/hr trip with no problems, this past weekend we're driving for about an hour then stopped for lunch. When we got back on the highway the engine started to surge and buck with a very erratic idle. The engine stalled after about 30 seconds of trouble and we pulled over. I let it rest for about ten minutes and the engine seemed ok for a while even though the problem has returned several times.

What I have tried is the idle relearn, no change. I unplugged the battery to reset the ECM, no change. The car was recently inspected and when i tried to check the OBD-I codes all I get is code 12 over and over.

Anyone have any ideas?

Thanks.

[sil]

i had this problem with my 88 olds 2.8, not sure what the problem was, and didnt do any major diagnosis becuase it was going to be ripped out and thrown /hybrid swap into my 93 gp

but currently the 93 gp has a simmilar issue with the bucking
and woul dlike to find out wha tit is befor ei do the swap

io hope someone has the answer :P

what should we be checking sensor wise?
and how to check the suspected sensor ?

[pepsi_coke]

Dont worry about code 12, thats like a "test". Anything after you get the code 12?

[90corsicaLTZ]

Anything after you get the code 12?

No, that's what's so frustrating. I see the SES light actually blink when the engine is having problems - yet it only gives me code twelve over and over.

[SS_EURO]

I had this same problem with my car when I 1st got it. I put a total of 1hrs on the motor and this started. I had to change the ignition module and coils. They get hot and act up when they cool down a few minutes later they work for a while and this repeats. But that is not to say it's your problem just a suggestion. Did you notice the temp gauge is it over heating?

[Juglenaut]

I had about the same problem with my 1990 beretta, it was my Memcal chip in the ECM.
Turned out that the coolant temp sensor shorted out internally and cause a surge in the ECM.

Also a good thing to do first is check fuel pressure, change fuel filter and check pressure again, the next thing to do only if fuel pressure is wacked is to change the regulator. Tap the map sensor if tapping it makes changes in rpm or stalls replace it, pull the plug tap it again and plug it in, if you notice rpm drop from unplugging it that is normal if it stalls that is not it should only stall if you plug it in without the vac line. The reason is the car should automatically go into a 'limp home' mode and if it is in that mode certain sensors are bypassed and will not fault a code even if they are bad, it may automatically go into this mode even if you reset the ECM and bypass and potencial faults, you can't reset the memcal by disconnecting the battery. Did you scan it before resetting the ECM??

My guess is that it could vary well be a fuel problem, or a ICM problem as these system are literally tied together and if you have a fuel problem most times it faults the ICM. If the ICM is bad most times it faults the o2, and or the map.

[85_Olds_Ciera]

I see the SES light actually blink when the engine is having problems - yet it only gives me code twelve over and over.

If I understand this condition correctly, SES blinks, the vehicle is running on limp mode...and "...the engine started to surge and buck with a very erratic idle..." might be the reaction if you were "fighting it," rather than finding an ideal throttle position...if possible. Surge/Buck represents timing/fuel/air not being correct...pre-programmed values...

Here's the newest limp mode for:

2007 GM 2.8L V6 VVT (LP1)

The ECM provides a limp-home mode for ignition timing, in the event either the crank or cam sensor fails. It also provides coolant loss protection, which allows the V6 VVT to operate safely at reduced power, even after there has been a total loss of engine coolant, so the driver can reach a secure location. The ECM allows a number of other customer-friendly features....

[TazMan]

I had the exact same problem with my GP. It was the ICM. At first it would just buck violently for a while, stop, and continue driving fine. Eventually it started stalling and I would have to pull over and wait a few minutes. I kept checking for codes but I didn't get one till the problem got bad enough to leave me stranded.

[85_Olds_Ciera]

It was the ICM.

ICM = ECM ???

[bszopi]

ICM = Ignition Control Module

It is located in the engine bay, underneath the coil packs.

[85_Olds_Ciera]

ICM = Ignition Control Module

It is located in the engine bay, underneath the coil packs.

Is this something similar in operation as the distributor's control module in the first ECM vehicles of GM with Carbs, whereby this modules fires up the vehicle, then computer takes over and controls timing aspects? This was also the "limp" mode then, with your Carb running 20:1 fuel burn...10 mpg on V8s.

Here, I would assume it uses a pickup coil off of crank, instead of distributor's shaft.