DavidS

Hi,

I searched the forum, and couldn't find anything similar, so I'll post this one up.

I have an '03 9C1 with 134,000 miles on it. It's been pretty powerful on the passes, but recently, I floored it going up a hill, and when it tried to hit the higher RPMs, it chugged, and kind of topped out, I even began to lose speed. If I let off the gas, and let it shift to 3rd, it doesn't have a problem.

After it chugs, the engine light blinks, but when I plug my laptop and ODBII reader into it to read, no codes show up. I recorded the RPM and it looks like it tops out at 4500RPM. What's the governor set to? I never checked before the problem, so I'm not sure of the max RPM.

I think it's getting worse with time. Definitely not getting better.

I changed the spark plugs, spark plug cables and O2 sensors as routine maintenance, no change to the problem at all.

Also, I think my gas milage is dropping with the introduction of this problem, my last tank was much less than normal.

Thank you to all the mechanics who take their time to read through and try to help out. It's greatly appreciated, and has always helped! Your knowledge is very valuable!

Cheers,

David.

DavidS

Just an update, I switched out the fuel filter, and there was no change in performance. I'm wondering if there's something else causing a low fuel flow, or low fuel pressure, I suspect the pump, but not sure.
Any ideas?

Also, has anyone ever heard of restrictions in the exhaust system causing something like this?

Thanks.

capucine

I would bet that your catalytic converter is blocked. Several impala owners had problems with theirs catalytics converters

DavidS

Thank you for the information capucine, much appreciated. The car has 134K on it, so the cat must be old. That would explain the sluggest power, and low gas milage, a major restriction in the exhaust system would do that.

I'll throw a new cat on there and see. Even if it's not the cat, it's due for a new one, so it's not really a waste of money.

Thanks for the help!

David.

Gwampa

Does yours have a downstream O2 Sensor? Might be good to hook the computer for some diagnostics? That would be cheaper than a new cat.

Jatt

exactly the same thing happened with my 01 3.8.
the best cheap repair was to empty the cat by rippin it up and welding it back again.
it worked n there seems to be more power.
but the only thing is, the CEL stays forever

DavidS

Thank you Gwampa!!! Your expert advice is appreciated and dead on!
It took me a while, but I found the time to get it tested and the computer indicated that the cat was a problem.
I have purchased a new cat to replace it, but need to get it installed.

Hopefully I get my power back!!

Thanks for the comment Jatt!! I hope I have the same clogged problem you do! If that's the case, the new cat will clear it up, it has bigger pipes than stock so hopefully I get more power too!!

I could see reducing restriction resulting in more power, especially based on how much power has been lost!

Also, I forgot to mention that engine oil started leaking as the power decreased, I'm guessing that the extra backpressure is increasing crank case pressure, squeezing out some oil, hopefully it stops after I replace the cat.

Also the old cat has a dent on it, so it probably hit something hard and caused bits to break off, which could have led to it's demise.

Thanks for all the help in diagnosing my problem, I'll report back once repairs are complete!

Cheers

David

capucine

David:

capucine

David: emtying the catalytic may be the cheapest way to get out of this problem but here in Canada we have to pass an emission test every so many years and the cat has to be healty otherwise the car will not pass the etest. Also by removing the guts inside I am sure that the computer on the car will tell you that something is not correct.

Gwampa

David, I've heard they make performance low restriction cats. Look around and you'll find what you want.