ChickenScreamer94

What does this mean? I havent went WOT in a few hundred miles, and was wondering if this is the reason? Can the carbon or whatever sits in the exhuast like that? Am I running rich? What is goingon here? My mpg kinda sucks (15 or so) and have 55k miles.

NVetro

richness would cause a bad mpg condition. Perhaps your O2's are so carbonized (is that a word?) since you haven't blown the carbon out in awhile that they are misreading and causing the car to run rich which dumps more fuel into the engine, causing bad mpg. What do you all think?

amean94ta

do this put some 110+ octane gas like cam2 in it dont mix with more than 1 gal of premium if the black goes away your running rich

slopokrodrigez

A couple of real easy things to check can save you a lot of heart ache. First of all I have met so many people with cotton air filters that don't know how to oil them it aint funny. Check and wash the filter real well. Then oil sparingly. Also consider cleaning the MAF (sorry i forgot to see what year your car was since 93's don't have MAF) Excess oil can contaminate them. Clean with electrical contact cleaner spray. Don't touch them.

Second, pull the vacuum line off the fuel pressure regulator and see if the hose is wet. If it is, change the fuel pressure regulator. It's wet cause the diaphragm has a hole in it and is leaking fuel into the intake through the vac line causing the engine to run rich.

Last, put a gage on the fuel line schrader valve like the one from Accel. Start and run the car until the fans cut on. Then shut it down. Check the pressure to see if it holds for a good long while. If it doesn't hold for long chances are you have a leaky injector. If it were you would probably have a cranking issue. (cranks longer than usuall) though.

The last things to do is have the wires checked for misfiring (doubtful) and scan the readings from the 02's.

Hope this helps

Seal

i believe black smoke is lean, and white is rich???

am i wrong?

Black_Z28

Black Smoke is rich, white smoke is water. You dont want to see white coming from your pipes. At least large quantities of it.

amean94ta

yes your wrong

dnz28

It depends, my car has a light grey smoke at wot. Black super rich. white is evil water. I aint sure what light grey is but it only happens when I smash the gas. O and blue is oil.

Seal

so, whats running lean?

Compstall

Black is rich. Rich is better than lean. My car blows black at WOT too.

ChickenScreamer94

i am getting a scanner this week so i will check the o2's. What are they suppose to be at anyways? Someone had said 100-800mv is this right?

I will have to check the FPR, but i kinda doubt that is it since it doesnt crank hard or whatever.

I will have to check knock retard with the scanner. I put and LT4km and it revs pretty fast while accelerating so i may rule that out-have to wait for scanner

I also have an idle surge i will have to check out. I am leaning toward O2's on that, and that may also be the reason for my bad MPG, but then again i only take 3 mile trips a day and stop every half mile at stop signs...

I just cleaned the MAF and reoild my K and N filter this past weekend. I used very little oil and let it sit overnight. When i oiled it it only covered the outer fins, but the inner groove was not wet with oil until it sat overnight, so i feel it absorbed without leaving an excess.

Compstall

My O2's are brand new, I still run rich at WOT.

slopokrodrigez

The 3 mile trips would have been nice to know earlier. Just to let you know, the ECM runs in open loop until the engine reaches about 140 degrees. It then goes into closed loop where it then uses the O2's and other sensor inputs to decide on the correct fuel ratio. When the ECM is in open loop, it ignores the sensor inputs. While in open loop, the engine is quite a bit richer than when in closed loop.

Since you continually take 3 mile trips, your engine is probably in open loop for most of those trips. There's your fuel problem. You need to take a long highway trip and check the fuel mileage then.

I think you don't have a problem.

BTW the ECM goes pig rich at WOT.

Z28Boss

Hey does it clear up and not blow smoke after a few times doing it. I live in the city and on weekends if I get out on a open highway I open it up and it blows black smoke for a bit. I think they call it "blowing the cobwebs out!" After a long time of easy grandma driving things can carbon up. Get on it hard a few times and see if it clears up. It probably will.