A few computer codes

[peppygozinya]

I am new here and I was hoping to gain some knowledge so here it goes.

I recently bought a 1990 Olds Cutlass Supreme with the 3.1 in it. It ran great when I bought it but now after it warms up sometimes it will run really rough. It will stall when I let off the gas and when it starts back up it sound like it has a big cam. It blows black smoke and has a real bad miss. I pulled the codes and I got...
15 - coolant temp sensor (low temp indicated)
21 - Throttle position sensor (signal voltage high)
23 - Manifold air temp (low temp indicated)
43 - Electronic spark control circuit+
53 - System voltage

I don't know where to start so any help would be appreciated.
Thanks in advance.

Rick

[86euro]

I would replace the coolant temp sensor first. There's a good chance it will take care of all of it.

[DEI37]

I would agree, pretty much. A cold coolant temp indicated to the PCM will make it run really rich, hence the black smoke, and run like crap.

I don't know how that will take care of the last code, as I don't know what it refers to, but you never know. Good luck to ya.

[tractorman]

I'd suggest that you look carefully at BOTH ends of your battery cables, especially the ground. Also, find where the grounds for the engine harness ground to the engine block, and check those connections. I suspect bad connections- likely on a ground circuit. Can't say for certain about these GM systems... but I've run into several cases over the years where several sensors on a wiring harness share a common power and/or common ground- if that connection gets screwed up, then it'll throw a whole string of codes (for every sensor or input/output on that circuit). I doubt that simply replacing the coolant temp sensor will fix your problem.

[peppygozinya]

Thanks Guys. This will give a place to start and I know that tracing wiring problems can sometimes be very time consuming. I will keep you updated as to what I find.


Thanks,
Rick

[peppygozinya]

New code

Ok guys, I replaced the coolant temp sensor and checked the battery cables and grounds to the block. The codes I get now are...

14 - coolant temp sensor (high temp indicated)
43 - Electronic spark control circuit+
53 - System voltage

Do you think the new coolant temp sensor could be bad? The car runs better but sometimes when you let off the gas it will stall. Would the code 43 be the coil packs? How do I test them to determine which one is bad?

Thanks in advance for the help

Rick

[peppygozinya]

Well guys, it turns out that the 2nd coolant temp. sensor was bad but the main problem was the computer. I found one at a local junk yard and now the car runs great.

Thanks for all the help.

Rick