Hey guys, got an old jeep here that's been sitting for a handful of years plus some. It's an 86 2.5l with the 5speed and 4wd. About 240000 on the odometer, but motor had a rebuild sometime before it sat.

So the problem..
Put a new waterpump, radiatior, fuel pump, fuel filter, motor and tranny oil change, oil filter, and so forth in this thing after sitting for so many years.. **** was just clogged up. Ran great around town for a little, then it didn't want to go. Diagnosed it down to what I thought was a clogged catalytic converter, but took it off and found it was already cleared out. Must be clogged muffler with rat nests. Took that back pipe off with the cat and muffler, now it drops off at the back of the transfer case there.

Take it around the block with the exhaust off, it drives great. I get back though and it's stuck at 3200 RPM, wouldn't go down at all. Let it sit for a few days, start it up and same thing.

Couldn't find a single vacuum leak, throttle cable is freed up, everything else checks out. Overfilled it a half quart, but couldn't imagine that to be related to my high idle issue anyways.

Any ideas for this trouble?

 

Fuel injected I think? Even the Carbed has an IAC. (Idle air Control). Cruiser is the man here, but do know the IAC does the job we used to do with the idle speed screw. Couple things....its a motor controlling a ram like thing (pintle). Puter controls it. Disconnected it will just stay wherever it was. Also, never power one up with it out. It if runs that ram off the end of the threads that's not good.

See cruisers tips found in my sig. Check wires to the .....TB, (or carb) and grounds. Gotta run...

 

Yea, forgot to add. TBI, fuel injected indeed. Thanks for the tip! I'll check it out.
I thought this might be an issue but I couldn't tell where the IAC was when I was in town working on it the other day, it's different than the set up on my automatic 88 4.0 with MPI instead. I'll dig deeper into it and figure it out.

Thanks again!!

 

It's not an IAC which stands for Idle Air Controller. It's an ISC. Idle Speed Controller.

It holds the throttle open as told to by the engine computer. They go bad/stick etc.

 

Yea, but if you call orielly's and ask for an Idle Speed Controller, like I did before this posting, and they will tell you they can't get it. Call back the next day and ask for an IAC and they will find it, then tell you it's also called the ISC... so yea, I don't know where I was going with that except for that oriellys never fails to cause more difficulty.

But regardless, I replaced this part and it fixed my idle issue. Thanks guys!

Next problem, it drives a few miles(or less) and then will sputter out(but only when I'm leaving from a stop or going up the driveway)

It's acting like lack of fuel to me, but I just did the filter and pump. The cap and rotor are 15+ years old, so I'm going for weak spark maybe?

Going to try replacing the cap and rotor and see will that gets me. Bought new wires, but got the wrong kind of coil wire, so that's 15+ years old too. If that's not it, then maybe Ignition Control Module is getting weak?

 

If it's the same type CPS they used up till 90, it can be checked in literally 3 minutes. That, as will as checking the sensor ground is found in Cruisers tips. A guy could chase his own tail all day trying to nail down problems with bad grounds....glad you made progress!

 

Alright, so I replaced the CPS sensor and the Ignition Control Module. Here's the deal, it starts up and runs good. It will hold at idle or 5000 RPM all day no problem in neutral Take it for a drive up the street, makes it to one end no problem, flip a ***** and take off from first and it sputters out without the clutch in. At this point, if I put in in neutral or push the clutch in AND rev it then it wants to sputter and die again.
I blew out the new fuel filter with an compressor at the same time as replacing the Ignition Control Module, and it seems like it got better but the problem is still there.
It will die coming back going up and going up the steep drive way in first or second, but if I kill it and start it right back up it runs fine.
The fact that shutting it off and turning it right back on makes me think it's a fuel issue, but the pump and filter are new. I'm thinking maybe the fuel sock in the tank is clogged up from gunk at the bottom of the tank?
I dumped the tank when I acquired the jeep but I didn't clean it out.

Any other thoughts? My bad for the overdetailed posting.

Recent new parts on this Jeep:
Water pump, radiator, thermostat, fuel pump, fuel filter, Idle Speed Controll Unit, Ignition Control Module(Not new but good, stolen off my other Jeep), Crank Shaft Position Sensor, cap and rotor, plugs and wires, oil change with filter for the motor, oil change for the transmission, and probably a few things I'm forgetting.

 

None of the stuff you're replacing will cause a dangerously high idle.

 

The Idle Speed Control Unit I replaced fixed the High Idle. That's no longer an issue. It idles where it is supposed to at.

 

Sounds frustrating. I had suggested checking the CPS, not changing it! Do you have around one ohm resistance between engine, body, and bat neg? Also the sensor ground circuit accessed at the TPS or the Map should likewise have similar resistance to those points.

 

I've seen posted it's possible to position the (free), fuel pressure gauge so you can see it through the windshield while driving. Partly because you have ruled so much out out, trying something like that sounds like a thought.

Once I had a carbed Toyota that was usually fine until I got the front up higher than usual. It could deliver fuel OK, till it had to lift it a couple feet higher. (finer line at the 5-8* range)

 

Note from DJ hear is a link on 2.5 TBIs
How-to Tuning & Troubleshooting Jeep 2.5L TBI Four-Cylinder Engines
http://www.4wdmechanix.com/Tuning-an...p-TBI-Four?r=1