Black Smoke and Poor Gas Mileage

Choppercpt · Post by **Choppercpt** » 14 Feb 2003, 12:58

I have a '97 850 Non-Turbo that I recently purchased from an estate sale in PA. The car sat for about 6-months and was only used on a very infrequent basis. When I first started to drive the vehicle, I noticed that there was black smoke coming from the exhaust during hard acceleration. At times during idle, black smoke can also be observed coming from the exhaust.

I have replaced the plugs, air filter with a K and N, flame trap and new rotor. The problem still continues. I've taken the vehicle to an independant shop (specializes in European vehicles) and they've put the vehicle on the analyzer. No error codes were revealed.

I'm looking for some help in troubleshooting this, as my gas mileage is average 12-13 mpg.

Thanks.

bajaman · Post by **bajaman** » 15 Feb 2003, 08:51

Obviously something is causing the injector duty cycle to be high. There are a host of things that could cause this, but I wonder if a faulty O2 sensor could be telling the ECU to cycle the injectors more often than what is required? Or you may have one or more leaky injectors. I don't know how much of a bitch it is to get to them on your car, but there are shops that can test them and fix them if that is the problem.
Have you tried running a couple of bottles of injector cleaner thru the system? I've personally had pretty good luck with VALVOLINE products.
It is worth a try and a very small cost. Get two bottles and drive uh..."spiritedly"...meaning get all over that beast! There may just be some buildup on the injector seats, and the life that the car had prior to you owning it was not the best.

Volvord · Post by **Volvord** » 15 Feb 2003, 09:42

I agree with the above diagnosis. I would first suspect sticking injectors that are not fully closing. An engine that sits for a while often exhibits this problem. As mentioned do try some injector cleaner, but I would suspect that the injectors will have to be removed and serviced.

Volvord 784VC
http://www.telusplanet.net/public/gilesij/Volvord/

Choppercpt · Post by **Choppercpt** » 22 Feb 2003, 12:26

The problem turned out to be the front O2 sensor. As a precaution I went ahead and did both the front and rear sensors. So far, so good.

DR

Post by **matthew1** » 22 Feb 2003, 14:16

This problem was not playing by the rules

. The check engine light should certainly have been lit, and codes should have been set, namely 2-1-2. Weird...

Glad you found the problem.

Choppercpt · Post by **Choppercpt** » 24 Feb 2003, 08:32

I agree with you about the problem not playing by the rules. Thats what the independent shop said.

DRR