Not running well

04-03-2009, 12:36 AM
I recently bought a 1987 Jeep Cherokee Pioneer from a friend at work for 400 bucks. I knew before I bought it that it had lots of problems. My plan is to get it running right and use it as a 4 wheeling toy so that I can get my 02 Grand Cherokee off the trails.

I have been making good progress so far. I am about six months and maybe $150 into it. The thing didn't start or run when I bought it, and leaked every possible fluid it could. Now it is running ok, and holding (most) fluids.

Most recently, I was having problems with stalling when slowing down, or if you rev it up high, and let off the throttle and the engine would stall. I replaced the IAC and the jeep was happy. Also had to replace wiring to the CPS (crankshaft position sensor) due to wires getting into exhaust and melting. Again, happy jeep. Starts right up, and runs great.

Today I was finishing up with the CPS repair and noticed a broken vac. line between the TB and MAP sensor. When I repaired the broken line, the engine would idle very high, and seemed to increase as it sat. It doesn't have a tachometer, but I would guess it is btw 2500-3500 rps when the MAP is connected.

I pulled the vac line back off the MAP and right away idle goes back down to normal. Hook it back up, and engine speeds up.:banghead:

In researching, signs point to either a failing MAP sensor, or perhaps the TPS?

Since this is merely a hobby vehicle, and things are tight financially, I can't just throw money into blindly replacing parts.:confused:

One more thing, I noticed on the boot that plugs into the TB where the vac line goes has two holes. Only the one line plugs into it, and the other one is empty. Is this right? I recently fixed up the rest of the vac lines as most were either broken or missing when I bought it. I can't find a diagram however of the configuration going into the TB.

Any ideas or input are greatly appreciated.

04-16-2009, 10:02 AM
Since this is merely a hobby vehicle, and things are tight financially, I can't just throw money into blindly replacing parts.:confused:

UPDATE: I tried replacing the MAP sensor, but the brand new one does the same thing, what am I missing here?

04-17-2009, 09:08 AM
:dunno: Wish I had some ideas for you on the high idle. Have you checked the intake to make sure it's not full of carbon? New air filter?

04-17-2009, 11:41 AM
yeah, thanks for trying.. i do have a brand new air filter, and i cleaned the throttle body. also ran sea foam through the entire vac system.. still idling fast.

04-18-2009, 06:25 PM
Sorry, I'm out. Hopefully some better electronics guys will be along shortly.

04-19-2009, 12:34 PM
Thanks for the help guys.. Could use any idvice on some body work too now.. Wrecked it into a bus in the mountains. :frown:

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Everyone was ok, and both my jeep and the bus were able to drive back home.

I think for it's intended purposes, the jeep is worth holding on to. I don't really care how it looks, as long as it is ok on the trails. I haven't had much time to look at the damage yet. Hopefully nothing major is too damaged. Like I said, the axle survived and I was able to drive it home on the spare tire.

Still could use some help with the fast idle too. Aparently there's no way to adjust the timing on this thing either. Sigh.... I have lots of work to do...

04-19-2009, 08:46 PM
Damn, that's some bad the roof buckled? Let me know if you want some commentary on insurance, I used to do liability for a large auto insurance company.

Glad everyone was ok.... and if it's your trail rig, then you're right...looks aren't important but character is!

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