1989 L98 Idle and Stalling Problems.
 

Like many, many owners it seems I have an issue with idle and stalling. The ECM is not showing any codes.

The car sat for approx. 4 years without running due to the above issue. I have replaced the following components over the past few months to attempt to get the car running properly.

New tank of gas
Radiator fluid
Radiator cap
Oil/Filter
Battery
Cap/Rotor
Spark plugs/Wires
EGR valve
Fuel regulator
Fuel filter
Bosch III injectors
Intake runner/TB gaskets
CTS
TPS
IAC


The car will start with no issues, fires right up and idles at around 800rpm, no knocks or noises. After a few minutes at idle the SES light starts to flash continuously and the car begins to surge. The RPMS jump all over the place, eventually the car will stall. I am getting that hopeless feeling...

I really do not want to take it to the dealership or a garage to get bent over a barrel.

Re: 1989 L98 Idle and Stalling Problems.
 

Sounds like a MAF sensor, but I don't know if you have MAF or MAP. Mine did the same thing when my MAF went south.

Re: 1989 L98 Idle and Stalling Problems.
 

I am starting to think I could have a head gasket issue. The car is not blowing any smoke, however I am getting a steady stream of bubbles in the coolant reservoir after several minutes of running at idle.

The supply coolant line to the upper radiator and the plenum also get extremely hot in only a few minutes. The return coolant line is also hot, indicating the thermostat is working, or at least open. The temperature gauge does not indicate overheating.

:confused:

Re: 1989 L98 Idle and Stalling Problems.
 

sounds like you may have more than one prob..
I would have a look at
pickup coil
ign module
maf sensor (clean it) also run it unplugged 2 c if its bad
also look at the plug wires for burns
Also a GM service manual will help you tons.. its worth the money

Re: 1989 L98 Idle and Stalling Problems.
 

try the key on test. Turn key to on position and your CEL should flash once very quickly and then turn solid. That means prom in the ecm is good. Otherwise i would suspect a faulty ecm.

Re: 1989 L98 Idle and Stalling Problems.
 

Key on test is good.

The car wouldn't start this morning unless I pumped the gas pedal a few times. I'm going to pickup a fuel pressure gauge and verify that I am getting the proper fuel pressure.

Re: 1989 L98 Idle and Stalling Problems.
 

ecm is probably bad

Re: 1989 L98 Idle and Stalling Problems.
 

I was sure the SES light stayed on solid before... anyway.

http://home.cogeco.ca/~chriscannon/IROCZ/startup.wmv

Re: 1989 L98 Idle and Stalling Problems.
 

my car did the same thing but i had to replce the egr and iac and add another fan

Re: 1989 L98 Idle and Stalling Problems.
 

ses light should not be on when the engine is running. Only when the key is in the on position. What code came back? You did the paperclip trick right? what codes flashed?

Re: 1989 L98 Idle and Stalling Problems.
 

The ECM isn't displaying any codes when I jumper the terminals. In fact, I am not even getting the Code 12.

I will have to search for a new ECM I suppose. Ugh...

Re: 1989 L98 Idle and Stalling Problems.
 

I think you found your answer. Call junkyards, they don't even have to be local ones. Look on the internet, although you can still find an ecm for about $25 at a local yard.

Re: 1989 L98 Idle and Stalling Problems.
 

The ECM issue is intermittent. I disconnected and reconnected the negative battery cable and the ECM flashed Code 12 once and then seemed to die. In the past the car would flash the Code 12 three times and then display any other codes.

I'll replace the ECM... Thanks.

Re: 1989 L98 Idle and Stalling Problems.
 

Solid state electronics are pretty stable and tend to either work or not work. There are no moving parts to wear out.

It's more likely to be a bad connection (moisture, dirt) then anything else.

Re: 1989 L98 Idle and Stalling Problems.
 

Fuel pressure reading at prime is 42psi and it drops to 34psi while cranking, and levels out at 36psi at idle. Within specs I believe...

Re: 1989 L98 Idle and Stalling Problems.
 

I may have the problem, or at least part of it. While poking around I pulled back the plastic wire wrap on the ignition coil and found this...

http://home.cogeco.ca/~chriscannon/I...20%2810%29.JPG

The wire is exposed and possibly corroded by weather. There appears to be some fraying.

Re: 1989 L98 Idle and Stalling Problems.
 

you need to check it w/ the regulator vacuum hose disconnected and plugged. should be 43.5 psi.

Re: 1989 L98 Idle and Stalling Problems.
 

ECM replaced and the car starts and idles like a boss; here's to hoping that solved my issue.