I think I found the problem - the computer

I finally had time today and smacked the ECM around (under the dash). First, i tried to start it, no start. So, I took the dash piece off, tapped around the whole area (silver box right?), adjusting wiring, etc, then sstarted it up. Ran great (little hessitation because of prior flooding).

I ran it for 30 seconds and beat on the dash area at the same time, and it didnt cut out or stall.

So I dunno, but at least I see that it is alive now.

It seems to make sense that it is the computer. When the problems began, i would experience:
1)No codes being stored even though CEL came on
2)300-400rpm semi-rough idle
3)Speedometer not working
4)Huge loss of power
5)Gasoline smell
6)electric fans come on randomly
7)takes FOREVER to warm up to operating temp (seriously like 45 minutes stop and go traffic)

These problems would occur in spurts - IE car would work fine, then the engine light would click on and all of the above would happen. Then it would go away randomly. (only until a few days ago when it wouldnt even start).

So I guess I need a new comp.

Not saying that an ECM swapped solved everything... but it sure made it run nice for a couple minutes.

http://webpages.acs.ttu.edu/blincoln/comp/IMG_0001.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0002.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0003.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0004.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0005.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0006.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0007.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0008.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0009.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0010.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0011.jpg

Doesnt seem to have the power it use to have though.

Anyway to tell if a prom is stock or not? Since I changed out the comps obviously I had to swap chips also.

you changed your pcm ? what year is your car, and what year did the newer one come out of :eek:

-- 91 Z -- ok :P what year did the other one come out of, same system and all?

Originally posted by lt1g3n
you changed your pcm ? what year is your car, and what year did the newer one come out of :eek:

-- 91 Z -- ok :P what year did the other one come out of, same system and all?

I bought a rebuilt one from Advance AP. I switched proms and was on my way.

so everything works perfect now?

hows it running now?

I took it for a 30 min test drive today. Not a single problem. Perfect idle.
Course it had way less power, probably because of the fouled up plugs.

Tried changning the plugs to see if that fixes anything? Even if they are fouled out, shouldn't they have burnt off by now?

I had that exact same problem. To see if it was the computer, I just tapped on it and it would either die or idle rougher. I got a new computer and it runs fine. I had all the same symptoms. Couldn't read codes, fan goes on automatically, car has no power and idles at 300 rpm.

Check these pics again:

http://webpages.acs.ttu.edu/blincoln/comp/IMG_0010.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0011.jpg

I know the stuff crumbles over time, but it sure looks something got all over it (IE water).

BTW the passenger side window does leak air around the side view mirror - when it rains it gets covered up. Im just wondering if the guy that owned it before me let it sit out in the rain and drip wet.

Originally posted by Pro
Check these pics again:

http://webpages.acs.ttu.edu/blincoln/comp/IMG_0010.jpg
http://webpages.acs.ttu.edu/blincoln/comp/IMG_0011.jpg

I know the stuff crumbles over time, but it sure looks something got all over it (IE water).

BTW the passenger side window does leak air around the side view mirror - when it rains it gets covered up. Im just wondering if the guy that owned it before me let it sit out in the rain and drip wet.

Could have been from a heater core that went some time ago:confused:

Originally posted by ThirdgenTa
Could have been from a heater core that went some time ago:confused:

Wow now that I think about it yea that is one thing he said he replaced.

Do I need to go through replacing these spark plugs again?
They have about 200 miles (3 months) on them, but I pulled cylinder 1's spark plug out (like I mentioned above) and it sure was pretty bad. It should burn off shouldnt it (assuming the motor isn't running rich any longer, which it doesnt seem to).

Also what is the normal idle speed for the motor? It runs at about 1200-1300rpm during warmup, and idles at 0mph in drive at about 700.

idle should be around 600 on an auto

Originally posted by Pro
Do I need to go through replacing these spark plugs again?
They have about 200 miles (3 months) on them, but I pulled cylinder 1's spark plug out (like I mentioned above) and it sure was pretty bad. It should burn off shouldnt it (assuming the motor isn't running rich any longer, which it doesnt seem to).

Also what is the normal idle speed for the motor? It runs at about 1200-1300rpm during warmup, and idles at 0mph in drive at about 700.

I'd replace that one plug that is fouled if the others are fine.

That sounds about right. You do want to get a scanner to see what the ECM is reading anyway if you want to adjust the idle and TPS. Your tach could be wrong. I know my ECM data matches the snap on gauge I hooked onto the wire but may differ from the stock tach.