1997 2.5 Jeep backfires

Old 09-09-03, 06:33 PM
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1997 2.5 Jeep backfires

I have a 97 Wrangler with the 4cyr motor. It's a 5speed. It will
backfire from time to time. Mostly right after I change into 2nd gear and try to give it gas after it has sat for an hour or two or overnight. If I let off it and feather the gas it will go away. If I give it gas it will stall out. I have the bigger throttle body and a cone filter right on top of it. It started it before I had swapped them anyways. I replaced the 02 sensor and that didn't help. Bad EGR valve? Do I need to get a Jet chip to recal. the timing and air?
Old 09-09-03, 07:59 PM
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suggest starting by having codes read and checking fuel pressure while the vehicle is acting up to see if you have a loss of pressure.
Old 09-09-03, 09:17 PM
mike from nj
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i'm curious, if you got a 'jet chip' where would you put it, in the glove box, or in your pocket. the engine's computer is a sealed piece that can only be modified by reprogramming it with an appropriate computer. also, how would it recalibrate the 'air'---with the turbo-vent gimmick thing that sits on top of the throttle body that spins the air?

if it did this before and after you replaced those parts---it's not those parts!!!!

is it backfiring out the intake or the exhaust?

out the intake is usually a bad plug or wire--or a very lean fuel condition.

out the exhaust is usually too much fuel.

is the cat still there and NOT hollow?

start with the basics, like already stated, before you start re-engineering the electronics that it was designed with.(like fuel pressure when the problem is happening)

let us know
Old 09-09-03, 10:11 PM
mike from nj
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check your vehicle's build date, it's in the driver's door jamb, on the sticker with all the tire sizes and recommended tire pressures. it will start with MDH ###### also, write down your engine's computer part # and post them both here, there might be a bulletin for your problem involving a reprogram, but it only applies to certain mdh's and part#'s

let me know
Old 09-10-03, 07:36 AM
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Throw out the bigger throttle body and air filter "improvement". Put back the stock set up. Even though they are not the problem as you state.

Most of those "performance" parts cause more headaches and problems than they are worth.

As Mike has alluded to, the aftermarket tuners don't know the vehicle, parameters and dynamics as well as the people that actually design, build and engineer the thing (That's Chrysler).

Back to the basics:

When was the last time it was tuned up? How many miles on it now?
Check engine light on? If so, what codes has Autozone extracted for you? (they do it for free). Post what they find.

Any other "performance" upgrades we should know about?

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