Brand new problem for the day :-)

So I took off from work like a normal day. Drove back home. Well there was a slow poke infront of me so I decided to pass him. I gave it some throttle, about 3/5 and it hits 2500 (+/- 100) rpms then it slowed some and made a "pa...pa" sound, then accelerated normal. I sounded liike it came form the tail pipe. I then gave it about 4/5 throttle at a stop light and it went "pa..pa.pa"

Year of XJ?
Engine in XJ?

Did you get a CEL? How about your catalytic converter?

Sorry

2001 XJ
4.0L

I always have the CEL light on. But I have a straight pipe after the cat.

How long have you had just a straight pipe? sounds like a back pressure issue.

killianbrody said:

How long have you had just a straight pipe? sounds like a back pressure issue.

Click to expand...

One month. But it has the two pre cats and the main cat so I would think it would be fine. It only did this today. But it was the coldest day I have had it straight piped.

If your in KS its probably cold out like here in MO the contraction of metal could have caused a leak at the points were the cats connect to pipe causing a different back pressure than before. look at in morning when you first start it and see if you can see fumes coming from any where they shouldn't. could be that or could be just that its colder outside than it has been? Had this problem with a toyota that i ran w/o cats had double cherry bombs instead fixed the leaks and no more pops. Mine leaked in front of the first cherry bomb were the cat should have been.