strange problem with the xj. need help

[Lifted93XJ]

OK so I was on my wayto sedona and all of a sudden the Jeep wouldgo way down on power then pop out tail pipe. Then it would come back up on power and then down again
I'm baffled ad to what would cause this. Any ideas would be greatly appreciated.

[KRAKER]

post up in the tech section.

[AZXJ]

any codes ?

When was the last time you replaced the CAT ?

[Lifted93XJ]

No codes, doesnt have a cat

[AZXJ]

renix or HO ?

[themud]

88 its a renix...

themud

[AZXJ]

didn't see a year posted.. wasn't sure.. sounds like a combination of thing to me.. possibly - intake leak, TPS failing, O2 sensor failing, Temp sensor failing... renix systems are fickle when everything isn't performing correctly.. hows the harness from the firewall to the sensors ?

[Brandoson]

I don't see a year posted either... besides 93 in the username

[offroader461]

im almost positive its a 89....mine does that sometimes and its the busted egr that causes mine....but mine only happens at start up

[jeep pox]

tps will do that too. at least my 89 did

[AZXJ]

didn't see a year posted.. wasn't sure.. sounds like a combination of thing to me.. possibly - intake leak, TPS failing, O2 sensor failing, Temp sensor failing... renix systems are fickle when everything isn't performing correctly.. hows the harness from the firewall to the sensors ?

I mentioned the TPS.. especially in the Renix system.. Hasta

[Lifted93XJ]

Sorry Fellas, it is an 88, i will replace the tps, just doesnt seem like a tps symptom to me. Normally Tps failure is more like a flat spot in the acceleration curve where there is nothing at all. This is more of a get warm and have no power. So far I have replaced cap, rotor and wires. I have a spare distributor I was thinkin about swaping in and thinkin about another coil as well. Could be o2 sensor related I guess. I was also thinking EGR cause Mine will not hold a vacuum but dang they are expensive new!

[AZXJ]

I didn't say replace it..you need to verify it's good or not.. there are several writeup's here on NAXJA on how to do this..

[live24wheel]

I had a similar issue on my 90 Renix. Turned out to be a failing coil. But as stated earlier it could be a number of things. Also as AZXJ stated I would test everything you can before throwing money at things.

[kastein]

Sounds like it could be a million different things, check your sensor readings since it's a RENIX with no codes to pull. You should see a varying voltage on the O2 sensor signal line, if you don't I would suspect it.

[Lifted93XJ]

So tonite I replaced my fuel filter and at first I thought It had fixed the problem and as soon as get got to running temp it started doing it again. I cant for the life of me get this things figure out. If anyone with more knowledge would be willing to stop by and give me a hand I would greatly appreciate it.

[MrClean]

My buddy had very similar symptoms on his XJ recently. I wanna say he replaced the coolant temp sensor or something dumb like that and it fixed it. I'll double check with him tomorrow and get back to ya..

[Lifted93XJ]

Cool, thanks. I am stressed from this

[kastein]

My bet is that you really should check things with a meter before replacing them (O2 sensor, TPS, temp sensor, MAP, etc) but feel free to commence throwing parts, it will help the economy.

If you insist on throwing parts, any parts that don't make a difference should be removed again and put back in their boxes for later use or as spares.

[Lifted93XJ]

Not interested in throwing parts at it. all tune up parts had a warranty and showed serious signs of needing replaced. I dont have the tools needed to check said parts. Thinking about towing it up to a local shop if I cant figure things out in the next couple days. Never have had to have anyone fix my vehicles before, but I cant figure this one out.

[Lifted93XJ]

Finally fixed. Ended up being the fuel pump. Thanks mud for the help.

[themud]

:cheers:

least ya got it figured out...
good luck with it..
Lemme know if ya need more help..

themud

[MrClean]

Glad to hear you got it fixed. I was right about my buddy's, so would've been my next suggestion..

[Lifted93XJ]

Thanks for all the suggestions everybody. Appreciate the help