Question about 2004 Jeep Grand Cherokee
Fitted new fuel filter but still cutting out on high revs
Ignition wiring failure may be causing this.
I would seek out the darkest place possible, open the hood, disable engine compartment light (have flashlight in-hand), manually raise the engine RPM up until missing is noted and look carefully for sparks where none should be visible
A defective coil pack can also cause this too and a visible spark checker (< $10 any parts store) that is inserted in each ignition line in turn will show which path is at fault.
Posted on May 21, 2014
You need to do some testing to determine the cause. First I would suggest that you install a fuel injection system pressure tester. Tape it to the windshield and go for a test drive. Does the fuel pressure drop at high RPM? If so, you probably have a weak fuel pump. Normal fuel pressure for your Jeep is 44 to 54 PSI.
Another item to test is for excessive exhaust system back pressure [above 3 PSI] You can obtain a kit which will allow you to perform this test with a simple carburetor fuel pressure/vacuum tester. Excessive exhaust back pressure will cause a lose of power. Most likely cause is a clogged catalytic converter. Without a pressure tester, simply loosen the exhaust pipe(s) from the exhaust manifold and road test the truck. If performance improves, you have clogged catalytic converter(s)
FYI, clogged catalytic converters are caused by driving for months with an excessively rich fuel mixture. Once you replace the converter(s) you need to find and fix the source of the rich mixture problem. Worn oxygen sensors or a defective MAF (mass air flow) sensor are the most likely causes.
Posted on May 19, 2014
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Posted on Jan 02, 2017
Ckean throttle plate inside throttle body...They tend to get dirtier than their counterparts in carbureted engines due to lack of fuel spray that kept them clean. If no luck with that, clean idle air control valve on TB. When doing this, don't turn the plunger, just clean with carb spray and replace. do not loose "o" ring seal.
Posted on Mar 20, 2009
Fuel filters are cheap and simple to change, so try that first. If that is not your problem it may be your catalytic converter. Before having that replaced, check your fuel return line. You should be able to blow thru the line with your mouth. If you can't, or it's really hard to do. . . then you have blockage. The blockage could be flooding your engine with fuel. Checking the fuel pressure with a gauge from an auto parts store may help you out. If the pressure is really high, then that may be your problem.
Posted on Apr 20, 2009
Only good hands on testing will give you a valid answer to that question. I'd pay special attention to fuel pump pressure (measured at the rail), cam, crank and throttle position sensors (and possibly map sensor).
Those are the items that are most likely to cause a shut-down...Others will make it run poorly.
Many of the larger parts outlets do code testing free. Have that done and see what comes up. At this point a code for O2 sensor should be ignored as that can often trigger when another more important one is out of range.
As I said, without testing I'm only making an educated guess, but I hope something here helps you.
Posted on Feb 08, 2010
Testimonial: "Thank you so much! We tried to get it to an outlet code tester and they can't do it without an engine light being on, which it isn't. Good info!"
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