jaysen lindbeck

Recently I bought a 1987 jeep cherokee 2 door, 4x4. With 159k miles. I had the water puno, power steering and brake master cylinder all done when I uptained it. And its been great for the 2 months ive had it. One night driving I was coming up an incline nothing huge just a hill. And as I reved pass about 2000rpms the engine just started to sputter and backfire so I let off and I costed up the hill. Pulled over inspected everything and i saw no issues. No smoke, so steam no burnt wires. So i got back in , it fired right up, and i made it home. The next morning I couldent get it to start for more than a couple seconds with out dying and now no start all together. My first assumption was the IAC, it gave me problems before as in when starting it would once a week maybe rev to 2000 and keep there untill i gave it a good knock on the throttle body. And,boom fine quiet idle. But I'm thinking ive knocked it silly. Any thought ? Or should i fire the parts cannon and replace all the sensors etc. What im most afriad of is it maybe it skipped a tooth on the timing chain. If any one wants more information I'll be happy to give it.

cruiser54

Don't start firing the parts cannon at it.

do a fuel pressure test. 31 psi at idle. should jump to 39 psi when the vacuum hose is pulled from the fuel pressure regulator.

I suggest you go to www.cruiser54.com and complete Tips 1 through 5 in the meantime.

Jeepwalker

Why would you think it skipped a tooth? Lots of guys get 300k mi on a 4.0. Are you getting codes? Does it seem fuel or ignition related? Start with basic troubleshooting like inspecting plugs for cracks, plug wires, cap, rotor. Put a vacuum gauge on it and inspect all vac lines. Plug major vac ports and see what it does. Check the EGR valve when starting that it's 'pulling in'. Check intake manifold that no bolts are loose (not likely but rule it out). Fuel pressure level?? etc...

It could be the IAC or even the TPS. It would be a good idea to remove the intake temp sensor and clean it with a soft brush and some carb cleaner. But rule out the other basic things first. Sometimes once a guy's ruled out everything else, it can't hurt to throw emission parts at an old vehicle to help increase reliability and also to have spares for future troubleshooting. Especially since most emission parts can be bought cheap on ebay these days...

Jeepwalker

..this doesn't have anything to do with your problem, but while you're working on your Jeep, pull the black plastic hose off the rubber grommet at the rear of the valve cover by the firewall, and clean out the oriface down inside the grommet. Stick a small 1/16" drill bit or piece of wire in there to make sure it's not clogged up (common). The hole inside is smaller (metered) than the vacuum line. If it plugs up (common) it can cause a lot of oil vapors to get 'sucked' from the front tube on the valve cover ...into the air intake stream, wet your vehicle's air filter with oil ...and literally soak it. That could cause a hesitation or lagging at higher RPM's too. When the warm engine blow-by vapors condense in the cooler air-stream the result is slimy oil. The slimy oil will work into the intake and gum up inside the butterfly plate and eventually the intake air temp sensor too over time. If the CCV (Constant Crancase Ventilation) hole in that grommet stays open like it should, it allows the engine to 'suck' in blowby vapors as designed. Checking that hole and keeping it open on an older, less clean engine is a good preventative measure to perform periodically.

jaysen lindbeck

Thank you guys for the swift responce from you all I will get back in a couple of days with my results. And test everything before fireing the parts cannon. Besides i just spent well over 700$ because the rear diff was seazing up, I,dont want to spent that much money on the other side of it 😂

Jeepwalker

I had a Jeep rear end lock up on the road once and it was a b%$# to repair. I had to cut the melted bearing out with a plasma cutter. Much better to do that job on the front side.

Megan jennings

I mean its rare that they skip timing. Id clean your throttle body plus the sensor then check cps man. When i got my jeep it sputter like a bastard cleaned the throttle body and sensor... Smooth sailing since... Well right now changing the damn rear freeze plug but we wontttt gettt inttoooo thatttt lmaoo

Megan jennings

BillyBoy

HE has Spoken... 😉

jaysen lindbeck

replaced the IAC this morning and boom. Back to a smooth running Renix, for now atleast. But im noticing some lifter tap.. On to the next issue, thank you all for the replys and suggestions.

cruiser54

The Tips are there to prevent things from cropping up in the future.......

Jeepwalker

Cruiser, your tips are very informative and well written. Thank you for taking time to write everything down in a concise and informative manner. And especially for so graciously sharing your knowledge with the rest of the community. Very commendable!!

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