LS1LT1 Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I took my 95 Roadmaster on a hot, sunny road trip today. I tried starting it again after it had been parked in the driveway for about two hours, and it ran very low and rough, seemed to be misfiring, hesitated when I tried to press the throttle, then eventually died. I was able to restart it but each time it died sooner and sooner until it would turn over then die. I smelled a lot of gas, so I stopped trying for fear of flooding it. My first inclination was an optispark failure, but the usual problems I hear about are from moisture buildup, which doesn't add up here.

Does this sound like an optispark problem, or could this have to do with the ignition coils, pcm, or something else?
 

·
Global Moderator
Joined
·
13,064 Posts
I'd get the icm tested at an auto parts store. Make them run many test cycles as icm likes to fail when hot.

We don't have a roadmaster service manual. But we have a 95 f-body manual. It will have troubleshooting, code troubleshooting, wiring diagrams, etc.

Did I mention you need to put car on an obd 1 scanner and scan for codes. Not all codes light cel. Among those who don't are the 4 ignition biggies. Dtc 16 & 36 for opti. And dtc 41, & 42 for icm.

In your other post about your problem, I suggested getting a PC based oscilloscope. It's the only 100% way of testing opti low & high resolution signals.

www.mediafire.com/?40mfgeoe4ctti
 

·
Registered
Joined
·
33 Posts
Shot in the dark, here, but I had similar symptoms on my Z-28. It would run real rough at idle, stall when I tapped accelerator, sometimes not start when it was warm, and often times had black smoke coming from exhaust. Ended up being corroded coolant temperature senator causing car to run too rich.


Sent from my iPhone using Tapatalk Pro
 

·
Registered
Joined
·
33 Posts
I ended up replacing temp sensor in side of block and sensor on water pump along with pigtails. Fired right up and haven’t had any issues since that time.


Sent from my iPhone using Tapatalk Pro
 

·
Global Moderator
Joined
·
13,064 Posts
The coolant temp sensor being off can cause running problems. So can other sensors not working correctly. The best way to check sensor readings is by having an obd 1 scanner that can do real time sensor data.

The sensor data stream can give good clues to what your problem is. Even if car won't run, you can still hook up to scanner. Then turn ignition on and check coolant temp data. If coolant is cold and cts reads way low or way high, you'll know it's the problem, or one of the problems you have.
 

·
Registered
Joined
·
1 Posts
I took my 95 Roadmaster on a hot, sunny road trip today. I tried starting it again after it had been parked in the driveway for about two hours, and it ran very low and rough, seemed to be misfiring, hesitated when I tried to press the throttle, then eventually died. I was able to restart it but each time it died sooner and sooner until it would turn over then die. I smelled a lot of gas, so I stopped trying for fear of flooding it. My first inclination was an optispark failure, but the usual problems I hear about are from moisture buildup, which doesn't add up here.

Does this sound like an optispark problem, or could this have to do with the ignition coils, pcm, or something else?
Some full-size GM 95's back in-the-day had a problem where there was a ground wire attached to the engine or the body in the area of the evaporator, and when this ground was loose, it exhibited similar concerns when starting/idling. It is easy enough to take a glance at all ground connections in that area, and who knows?
 
1 - 6 of 6 Posts
Top