G50: 1991 Q45 - Strong Black Smoke - Bucking and Jerking - Periodic Stalling

[lino]

I've been getting a lot of black smoke coming out of the muffler for the last couple of months. The black smoke is so strong that if I don't wash the car at least once a week, I have to use a wax stripper to remove the black residue off the rear bumper and trunk lid and then wax the car. I drive approx. 150 miles per week, mostly city driving.

I swapped out the MAF with another used one and it didn't help. I'm planning on buying a brand new one. I get bucking and jerking which happens mostly when driving on the highway between 50mph - 60mph. The car is slow off the line and feels choked most of the time. The engine hunts for idle when stopped at a traffic light usually dipping too low. Also, sometimes when I make a sharp turn the engine will stall.

Has anyone else experienced a lot of black smoke?

[elwesso]

I would start with checking your MAF voltage at the ECU and see what its doing.. If the MAF voltage is OK at the ECU then you need to look elsewhere.. Pretty simple to test, you just do it like you've done in the past and just leave the volt meter hooked up (maybe get some alligator clips to clip the lead to the pin).. In the mean time, why dont you just put some masking tape on the bumper so you dont ruin anything!

[goody90q45]

Any corrosion on the MAF connector pins? Tighten the connector pins also so it doesn't wiggle when clipped on the MAF.

[maxnix]

Just abut has to be MAF related. No leaky injectors, right?

[lino]

I'll check it out next day or two Wes.

Mike, I've already done that and checked it and cleaned so many times.

Brian, my injectors seemed fine last time I checked, but I'll check them again.

Thanks guys.

[maxnix]

Well, you can check the solder joints on the board. But dont drive it like that or you'll be buying new cat$ also!

Get a new MAF then we'll continue diagnosing if need be.

No recent injector removal and installation?

[lino]

Well, you can check the solder joints on the board. But dont drive it like that or you'll be buying new cat$ also!

Get a new MAF then we'll continue diagnosing if need be.

No recent injector removal and installation?

I replaced 2 injectors last year when I did the plenum hoses. I also put in a new injector harness at that time, but nothing since then.

Is there a part number for the MAF connector?

[maxnix]

Yes, but call Joe. It was a running update in 1994 or early 1995 to a 4 conductor connection.