Smoking Catalytic

Ok, got 91 Cherokee in May. Been taking 2-4 hour long trips camping etc... this summer. On my first long trip I pulled over and the Cat was smoking really bad. Literally people around me were coughing, lol. Driving at 120Kms I didn't really notice anything coming out the back but when I got it up to 140 it started billowing out the back. I got home after that trip, pondered what the problem might, checked all my fluids and changed the oil. Next weekend I was out again. This time it wasn't nearly as bad. I didn't notice anything coming out the back this time, even up to 160 or so. When I stopped I still could see it smoking, again not as bad. Several trips later its still doing it, though not as bad as it was that first trip it still smokes!!!

I've had my mechanic clean the injectors. I've had another check the back pressure and Cat. The Cat is fine. The jeep is running like a dream otherwise. It's a rebuilt 40k or so ago.

I'm not losing any oil or Rad fluid. Tranny fluid appears to be ok.

On a really hot day it even looks like stuff is seeping out of the Cat. I've been going to my mechanic for years and he says its fine with only a 1/2 a pound of back pressure.

Anyone have any thoughts on this or encounter anything like this?

Thanks!

What your seeing is nothing more than steam, it's normal if you burn cheap gas with 10% Ethanol

Slow down to the legal speed limit and save gas. That way they won't put ethanol in the gas and your vehicle won't smoke.

sure doesn't smell like steam, here the limit on the highway is 110 so 120 isn't too far off, lol, pull out to pass and i'm up to 140 pretty quick

N

Sorry about that, but I did have to do that comeback. It was so open. I've been to NB and it does has the best speed limit. I mostly go to ON where the speed limit is a bit anemic.

XJNATE said:

sure doesn't smell like steam, here the limit on the highway is 110 so 120 isn't too far off, lol, pull out to pass and i'm up to 140 pretty quick

N

Click to expand...

What you see is steam, what you smell it Hydrochloric acid.




Un-burnt fuel is converted to water and Hydrochloric acid.

Ineteresting, I look like a moron when I pull up to a gas bar and smoke is billowing from underneath. Never heard or seen that happen to anyone else. Guess it can't be anything serious if I'm not losing fluid and the back pressure is normal.

N

Try a different brand of Petrol and see if it goes away.