B]null[/B][B]HELP HELP HELP 88 CHEROKEE 4.0 BACK FIRING REAL

[mburian02]

1074994

ok, this is what happened.......i picked up a jeep from a guy pretty cheep and it had set for 2 years when i got it running it was real sluggish and alot of black smoke so i figured the cat was plugged........so i beat on the cat for a while with a hammer and man did alot of **** fly out of that exhaust then i took it for a drive and it was runing real well the all of a sudden it backfired and it started running like crap againso we pulled the cat back off and looked down the muffler and it was totally plugged so we cleaned it all out and put it back together and no at a low idle it runs sweet but as soon as you hit 1/8 throttle it starts back firing sounding like a 12 guage shot gun what can it be?????????????i am totally lost here please help..........could it be the m.a.p. sensor or something else like that ???????????? :-O mburian02@sprintpcs.comnullHELP HELP HELP 88 CHEROKEE 4.0 BACK FIRING REAL BAD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!![addsig]

 

[Tug-n-pull]

1074996

Welcome and hope you get all the answers you need here to get you going. !st you say it set for three years and you just fired it up and took off. Bad start! REgroupe and start over.

The fule was most likely a tank of worthless crap. Drain and re fule with some good gas. the fule filter if not bad before is most likely gummed up with the crappy old gas. Do a tune up plugs wires cap rotory button air filter ect....

Pullthe cat and muffler and chec the muffler to see how clogged it is and replace just the muffler. You will need some back pressure to run right. form there you will be able to tell much more about what all it needs. Two years setting can do alot to an engin, be kind to it and fill your way through the system till you get her puring like a little cat. I hope this helps some.

With all of that said this is what I would have done and there are more weathered wrench heads here than I so good luck as they come to give better advice than I ever could. tug[addsig]

 

[XJNick]

1075031

Yes definately check/replace the MAP sensor first then check for vacuum line leaks or cloggs. Also might check that the EGR system is working properly, the EGR valve might be stuck open. Once you get it running i'd return the exhaust to the original setup (Cat & Muffler)

-Nick [addsig]

 

[mburian02]

1075124

i will try that and see what happens anymore info would be helpful considering i am nowhere near a jeep mechanic

thanks in advance
[addsig]

 

[mburian02]

1075246

is it really necesary to put a new cat on?????or wll the hollow one work?????[addsig]

 

[XJNick]

1075306

Well, that's debatable.

I'd put a properly working catalytic converter back on because
1. It's illegal if you don't
2. You keep the exhaust backpressure what it should be
3. Internal Combustion Engines put out plenty of Emissions even with the proper emission system components installed, so why make it worse?
4. You won't pass emission testing otherwise (if you have it)

Just my $.02
-Nick

edited by: XJNick, Jul 09, 2003 - 03:40 AM[addsig]

 

[Tug-n-pull]

1075336

To each his own but an incress of power and a 10% incress in mileage over rode my concerns of emmissions. Fule consumtion vs. Air polluition? Preformance vs. Leagality? Who is to bless and who is to blame. Ever speed on the open road? that is aginst the law too. Ever use charcoal to grill your burgers? That causes more emissions than a tank of fule with out emmission control. I guess it is all in how you see thing as to who is right and who is wrong. To much goverment BS in the world today. No cat and a Flowmaster plenty of back pressure, great preformance, and sound real good! love it tug[addsig]