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96 4 cyl hesitation, rough idle, ign noise


NAXJA Forum User
I'm having a problem with my 96 2.5 engine I have never seen like this before. It has 186k, in good shape. This is intermittent and runs fine otherwise.It sometimes on accelleration, has a severe stumble that clears up with a muffled backfire in the air cleaner box sometimes, along with a check engine light usually and a poor idle. The code is 27.I have checked everything and am now looking at the injectors/fuel pressure.I also am now(all the time!)getting a really bad ignition noise except on a local station ,on the FM stations and when idling outside and the TV is on, a oscilloscope type bar running up the tv screen!I have checked all engine grounds and the plugs look ok as well as the plug wires/ dist seem to be okay.It runs great otherwise so it is a mystery to me! This is my 5th Cherokee and I've never come across this so any help would be appreciated. It does have a little exhaust man.leak and I would say the timing chain has a little noise too, and the oil in the air cleaner box, but otherwise okay.
Not quite sure I understand all the way what you're talking about.....ignition noise? What kind of noise, like a pinging? And you say a bar up the TV? Is it some kind of TV you have mounted inside (like one of those radio/dvd/tv fancy unit things)?

My buddy has a 96 Dakota (also with the 2.5) that suffers from bad blow-by (oil in the air filter). He came up with a solution for it by eliminating that breather that runs from the valve cover to the air filter box. He installed a different type of breather that just sits in the top of the valve cover and collects all that oil. If you'd like, I can get the specs on what he used....I believe it was a part he picked up at Autozone...
believe it or not, it picks the engine running up on my in house tv,when idling and also have bad ignition noise on all but a local Fm station.It causes almost the same pattern if you hooked up the jeep to an Sun analyzer, four bars of full horizontal width going vertical.The tv stations here are 100 miles away so that may be a cause but I have never seen this before.it all just started recently!The ignition noise doesn't go away but the hesitation/rough idle does when the check engine (code 27) light goes out, then it runs fine.All my previous jeeps had TBI or carb so I am mystified and not too familiar with the problems of the EFI system.:dunno:
Well that's definitely a first for me......

Still a little confused on this ignition noise you're talking about. Can you describe the noise?
It's just a typical ignition noise, rises and falls with the engine rpm, the type you have from older vehicles, I have never seen this on newer ones, very odd.The Jeep ran fine today of course and had no problems, but the ign. noise is still there.
If you're getting ignition noise, there's almost certainly something wrong with the ignition, no matter how things look. I'd start with the wires. A broken conductor inside a wire can do it. A defective plug can do it too. Plugs can be bad and still look good. Plugs are cheap, and it may be that the quickest way to diagnose them is to put in a set. Don't forget to check the inside of the distributor cap for damage or carbon tracks, and make sure the center button is making good contact with the rotor. I'd start with the plug wires, though.

I didn't see this post when I responded to your other post about the code 27. I'd check out the ignition first, but still do a harness and injector check too, but I very much doubt a bad injector harness would put out enough stray energy to cause TV interference. It might cause some on the car's own radio, though.
Thanks I'm going to pull the wires and check all that , plugs look ok but I will try a new set, they are autolites but am going back to Champions.The TV thing is really weird, but here(no local TV all the way to Texas/Okla) we are about 75-100 mi. west of the transmitters in Little Rock, so the signal is weak.i appreciate all the suggestions, I am used to my 89 TBI and it's a new deal with this EFI, my older 4.0 had the renix.