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Unread 04-12-2013, 04:29 PM   #16
ratmonkey
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probably crank sensor or the computer then.

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'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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Unread 04-12-2013, 04:35 PM   #17
JohnCrabtree
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Quote:
Originally Posted by ratmonkey
probably crank sensor or the computer then.
The computer being the PCM?

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Unread 04-12-2013, 05:27 PM   #18
JohnCrabtree
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I took my PCM to wiring harness connector off. There is some gold gunk on the tips of most of the connectors. I sprayed some brake clean on it. Below is a picture after having put brake clean on it.

image-815177813.jpg

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Unread 04-12-2013, 05:52 PM   #19
JohnCrabtree
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image-2181994555.jpg



image-3116858864.jpg



image-2243525238.jpg



image-3939995378.jpg

Photos of the inside of the pcm along with an up close photo of the connectors. As i said before, there is gold/yellow crud on the connectors. There also seems to be a bit of corrosion around some parts (not sure what they are called)

image-2867189816.jpg

Along with some cracking in the jello stuff around the round pieces

image-221673394.jpg

Is this pcm shot?

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Unread 04-12-2013, 06:03 PM   #20
ratmonkey
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that cap is deformed. so it's likely blown. i'd say the computer is your problem.
those can be replaced, there's a write up on the forum. if you feel up to soldering on a bread board.
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Unread 04-12-2013, 06:17 PM   #21
JohnCrabtree
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Quote:
Originally Posted by ratmonkey
that cap is deformed. so it's likely blown. i'd say the computer is your problem.
those can be replaced, there's a write up on the forum. if you feel up to soldering on a bread board.
What do you think the cost for a new PCM will be at autozone/napa/orielys? I'll probably replace it.

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Unread 04-12-2013, 06:18 PM   #22
JohnCrabtree
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And what part is the cap and how do I know that it's blown? Trying to learn here, not just make my jeep stop dying haha

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Unread 04-12-2013, 06:54 PM   #23
ratmonkey
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capacitor. they're usually nice and cylindrical. those look a bit deformed.

autozone etc use cardone brand pcms. not the best in reliability. but there's a warranty. bout 250 for one. do not buy from any outfit based in florida when online shopping.
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Unread 04-22-2013, 06:57 PM   #24
JohnCrabtree
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It did it again today on the highway this time. First time it's done it on flat ground. I was actually on my way to a local mom and pop shop where I'm trying to get a job or internship. I brought it there, the owner checked the codes for me, they read nothing. I mentioned that I had thought it might be the throttle position sensor. He agreed and he used his super special scan tool to check how much the voltage it was reading at idle and full throttle. At idle it was reading .6v (.2-.9 is normal) and at full throttle it read 3.6v (4.5v being normal). When I got home I grabbed my volt meter and checked the voltage on the connector to the TPS. Following the instructions in my haynes manual, I put ground on the 1st terminal and the positive on the 3rd terminal. It read 5.1volts (normal being 5v).

Correct me if I am wrong but it seems to me that the TPS is bad.

Please confirm my spec numbers as I got them from my haynes manual and everyone on this site seem to hate the haynes manual for ZJs.

5.0v on the harness to TPS connector (key on)
0.2v-0.9v idle throttle
4.5v wide open throttle

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Unread 04-22-2013, 07:43 PM   #25
ratmonkey
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WOT is supposed to be less than 4.6. anything over 3.5 is usually pretty much ok.

the more important readings are in the middle. make sure it has a nice even sweep through the full range with no peaks and valleys.
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Unread 05-07-2013, 06:44 PM   #26
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Finally got the bright idea to record my problems with my phone.

Here is the first video, it shows me trying to keep the engine from dying. Most of the time in this video I could not even get it to start and stay running (it would start at die) without giving it gas.

https://www.youtube.com/watch?v=Rt-3NFden6E

This video was taken before the above video. It had been dying so I decided to video tape the codes. After it flashes the codes (12, Loss of power to PCM, and 55, End of codes) the check engine light has some kind of issue, I don't think it's supposed to flash like that.

https://www.youtube.com/watch?v=VsLezMMYTGo

Anyone have any ideas on what I should test?
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Unread 05-07-2013, 07:04 PM   #27
JohnCrabtree
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Quote:
Originally Posted by ratmonkey View Post
i would check the capacitors in your computer, all the tune up items(cap,rotor, wires, plugs), crank sensor, and o2 sensor wiring.
After seeing that video still think that I should check all those? I have no idea how to check the capacitors, What should I look for on the cap & rotor? Ohm test the spark plug wires? What's the spec on them? Last time I looked at my plugs it looked like they had been burning a bit of oil, which is nothing that seems unusual to me in a 190,000 20 year old truck. What is the spec for the crank sensor? What am I looking for in the o2 sensor wiring? Should I be looking for breaks in the wiring or should I do a voltage test or?

I have a haynes manual for my jeep but everyone on JF seem to think its a PoS repair manual (At least for ZJs). Should I just follow the testing instructions there and use the numbers they provide or do you have something else in mind and are their numbers correct?
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Unread 05-08-2013, 01:19 AM   #28
AaronButler
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if you needed a new computer, you can probably find a used one for about 200-250. caps/plugs/rotors/wires should be done anyway just for tuneup purposes, and they are easy potential fixes. I am leaning towards a TPS though, they are about 35 bucks at auto zone. Id clean your TB while you are at it.

Other shot in the dark things you can check:
throttle cable could be stretched
listen under your hood for vacuum leaks (although I dont think that would cause the results you are getting)
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Unread 05-08-2013, 09:18 AM   #29
JohnCrabtree
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Quote:
Originally Posted by AaronButler
if you needed a new computer, you can probably find a used one for about 200-250. caps/plugs/rotors/wires should be done anyway just for tuneup purposes, and they are easy potential fixes. I am leaning towards a TPS though, they are about 35 bucks at auto zone. Id clean your TB while you are at it.

Other shot in the dark things you can check:
throttle cable could be stretched
listen under your hood for vacuum leaks (although I dont think that would cause the results you are getting)
Replaced the TPS last week, cleaned my tb yesterday.

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Unread 05-08-2013, 03:29 PM   #30
ratmonkey
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yeah, i think you've got a computer problem.
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