97 TJ 4cyl - ticking/tapping noise after replacement of plugged cat

I posted a couple of weeks ago concerning a problem with my 97 TJ (4cyl, auto, 130K) and a lack of power at freeway speeds. I got some good suggestions on here, the general consensus being that it could be a plugged catalytic converter.

After that post, the problem apparently went away - until this past Friday when the car lost almost all power, but I was able to limp it home using very light throttle openings to (eventually) reach about 25/30 mph.

Yesterday, I got it to the shop to have a new cat fitted. This has restored the power but now another (somewhat more serious sounding) problem is evident:

I now have a ticking or tapping sound which gets faster with increased engine speed and louder under wider throttle openings. At idle or when cruising or when revving the engine gently at a standstill, you can't hear the noise. But when any load is applied to the engine, the noise is apparent.

I made a couple of mp3s to document the sound. The first is the vehicle standing - you can hear the noise when I applied rapid throttle (0:01, 0:13,

0:19), but not when applying gentle throttle (0:03, 0:22) to reach the same engine speeds:

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The second is a short cruise around the block. You can pretty much hear it at any time I accelerated:

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I presume that in limping the vehicle home and to the shop, I broke something. Under the hood, it sounds like it's coming from the top end of the engine - but I don't have a stethoscope or anything to be able to say for sure.

Any ideas here on what this could be ?

Thanks in advance for any help Keith

Reply to
Keith Orbell
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Reply to
L.W.( ßill ) Hughes III

L.W. ("ßill") Hughes III did pass the time by typing:

That's what I'm thinking.

I'm also thinking the ECU hasn't adjusted back from where it was and the OP should take the battery off for about half an hour and then let it re-learn.

Reply to
DougW

It's an exhaust leak.

Reply to
bllsht

Was that there before the exhaust work? It sounds rather like a cracked manifold or just a crappy install of the catalyst letting exhaust leak.

Keith Orbell proclaimed:

Reply to
Lon

Reply to
L.W.( ßill ) Hughes III

Reply to
Will Honea

Buy a stethoscope. Even the fancy Littmann medical scope that I have, with my initials engraved on the probe, was less than a hundred bucks. The cheap ones are a lot less, and function almost as well.

Earle

Reply to
Earle Horton

Well, if they are anything like the incompetent butchers that changed our Cherokee's exhaust, you sure could now have a cracked manifold.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

Heh, four, v8 and v6 exhaust manifolds are pretty tough, simply because they are shorter and the hooligans who call themselves mechanics usually can't get enough leverage to break them. That is not to say that they didn't make the manifold to header pipe joint leak. I was thinking exhaust problem too, because of the proximity to the catalytic converter repair. It is hard to see how the OP could have damaged internal engine parts, but there is always a first time.

Earle

Reply to
Earle Horton

I had a free warranty cat replacement where the new cat had a notch at the end of the pipe that lined up perfectly with a similar one at the back end of the exhisting pipe from the manifold. Made a very similar sound until fixed.

Will Honea proclaimed:

Reply to
Lon

Reply to
gregw45

Reply to
philthy

To follow up on this, I had it looked at in the week.

There were two problems - a bad manifold gasket and a cracked manifold.

Thanks for all the replies and good suggestions. Keith

Reply to
Keith Orbell

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