Mmurdock

I have an '89 Cherokee with a 4.0 and 5-speed and 201,000 miles. I picked it up a few weeks ago for my sister-in-law. It ran good when we bought it and I've been slowly going though it. I'm trying to spend as little money as possible on the thing, so I've been repairing vacuum lines and given it a good tune up (plugs, wires, cap, rotor, fuel filter).

Currently it starts well but the idle will change slightly about every 10-seconds or so. The idle speeds are neither too high or too low but it just kind of slows down a little than picks back up again.

When driven it has a stumble as you reach higher RPMs (probably around 2500-3000 there is no tach on this rig). The stumble feels like a multi-cylinder miss and goes away as soon as you ease up on the throttle or shift up a gear.

Today I cleaned the Idle Control Air Valve and planned to pull the EGR valve and clean it as well but I cannot figure out how to remove the Torx screws which hold it on. I have a #40 Torx socket but there is not enough room for it to fit on either of the bolts. I'd appreciate any tips what tools you use to remove the thing. I was able to use a pair of needle nose pliers to move the EGR shaft in and out. It seems to move smoothly but I'd still like to pull the EGR and give it a good cleaning whether it's the cause of my stumble or not. I'd also lile to know if anyone has anyother suggestions on what else to check.

rrich

Doesn't sound like an EGR problem.

Try spraying a mist of water around the ignition - wires, cap, coil wire, and especially the coil. If you can hit a spot that causes it, you found it. Coils are famous for your symptoms.

New plugs? Use the ones called out on the underhood label - not the ones the parts house wants to sell you. Gap them like the label says.

Dump a can of Techroline in the fuel tank - it may just be
dirty injectors. It will slowly and safely remove the junk.

Let us know.

cruiser54

When tjwalker awakes, I'll bet he'll post up a little deal on refreshing the grounds. You need to do that before wasting any more time on this.

tjwalker

I'm UP and coffee is in hand!

1. Did you clean the throttle body when you cleaned the idle air control? Very important as they get carboned up over time and miles

2. Testing and adjusting the throttle position sensor is never a bad idea as they are not an uncommon failure.

3. Verify that you have 31 psi of fuel pressure at idle. Then disconnect the vacuum line leading to the regulator and the pressure should jump to approximately 39 psi.

4. Here's the deal on grounds. Especially important on 87-90 XJs.

Even if this is not the problem, freshening and verifying grounds may prevent future problems.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

cruiser54

Good morning Tom, and thanks for the help.