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Engine Prob

XBoBJ

XBoBJ

NAXJA Forum User
Location
Spencer MASS
Recently my jeep has been acting weird, back firing out of the intake, lack of power. i just went for a quick ride to the store and got home and looked under the jeep and my headers where glowing red, do u know what could be causing this. thanks+

99xj 4.0
 
yeah thats what some one else mentioned, how do i go about adjusting that, or do i need a new one. also the idle has been a little higher than normal
 
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well an update on this, any help would be greattttttttttttt. i hollowed out the cat and ran a compression test on my jeep. the thing runs worse. and the compression is fine between 150 and 125. now where else do i look every time i drive the headers turn red hot.... what is the next thing i should do..... tps? and when im at 1/4 throttle it seems to run fine. anyhting over that it runs like crap backfiring and everything.
 
This is indeed a strange one but the CPS would not be suspect in my opinion. Do you have any check engine light? If so, PULL CODES immediately for clues.

CPS failure results in missing, no-starts; back-firing seems to speak to a fuel delivery issue of some sort. Have you performed any fuel pressure testing yet (both static and dynamic and compare to factory spec) It's easy. Put a fuel pressure gauge on the schrader valve on the fuel rail. Check for vacuum leaks regarding your idle?? Somebody else please chime in with some other possibilities.
 
yeah anyone please help.... fuel pressure seems okay i didnt do a test but i pushed the schrader valve and fuel came out. im so lost..... also the fuel pressure seems to be back to normal. also could my muffler be the culprit?
 
I don't think a CPS would cause these symptoms, but it wouldn't be the first time i've been proven wrong.....it's just that it does not have the typical symptoms (no spark, no fuel, cranks but doesn't run, sometimes a CEL). Again not ruling it out, as there may be something about them i'm not aware of....just saying it's sounding unlikely.

I was going to suggest a clogged cat, but since you hollowed that out already.....

I suppose the muffler might could cause that....say if one of the chambers inside broke loose and is plugging everything up....but I would think you'd notice a definite change in tone if it were clogged.
 
im lost i dont know what im going to do...... any suggestions on where to look now, should i give it a tune up... clean the tb.....
 
XBoBJ said:
yeah anyone please help.... seems okay i didnt do a test but i pushed the schrader valve and fuel came out. im so lost..... also the IDLE seems to be back to normal. also could my muffler be the culprit?
Click to expand...
EDIT
 
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starts fine idles fine drives fine unless i get on it or hit some hills, this morning it started i gave it gas and it almost stalled out...... ill check the timeing. also the exhaust smells like shit now since i hollowed the cat
 
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if it starts right up, it probably hasn't slipped timing

the only i've time seen glowing manifolds, is from a melted-down catalytic converter that was so plugged, the exhaust was barely exiting the tailpipe.
 
yeah ill take pics of the headers there red hot. i have nothing in the cat its empty..... i dont know.......... seems to do it worse in the higher gears also, 4 i cant barley drive in it unless its over 2500 rpms anything below that it back fires and just bogs. thanks for all the help guys. also this is getting progressivly worse
 
im going to try a tune up after work today, cap rotor wires and plugs and check the timing. see what that does......... ill let you guys know
 
I've seen exhaust manifolds get red hot before and it was a multitude of things. First was a stretched timing chain. Second was the throttle position sensor shorting out thus causing too much fuel and the extra fuel being burned in the exhaust. I'd suggest telling us how many miles are on it. Get a cheap repair manual. (haynes/chilton) Then check your sensors using a multimeter. Rent a pressure gauge as just pushing on the schraeder valve does not tell you that the pressure is right. Just some idea's to start with. Is the CEL on? (Check Engine Light)
 
i got a haynes manual, i was an electricans apprentice so i got the multimeter, what should the tps voltage be at? i wish there was a CEL light, would make my life so much easier. im thinking its the TPS shorting out, the jeep just hit 150k and i have a pressure gauge and will check the gas pressure tonight. thanks for the imput much appreciated, :patriot: hopfully i find the problem with this thing.....
 
did a tune up, timing is good. did nothing. tried getting data off the pcm with an OBDII reader but nothing is coming up, i tried the same reader on another vehicle and it worked every time i pull data it just shuts off,,, i dont knowwwwwwwwwwwwwwwwwwwwwwwwwww this jeep sucks :flamemad:
 
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yes up stream o2 is brand new factory, didnt touch anything else i dont want to start guessing and having it be wrong, also since my cat has been hollowed out there has not been a cel on yet and ive done 50 miles i find that kinda weird
 
My buddy had an OBDII XJ and it started to run like hell, kind of like you describe but never for enough time to see the headers glow. I brought over a throttle body i had laying around and swapped the MAF and TPS onto his and it cleared up the problems right away.
 
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