TBI fuel injection issue...

[Eddies66]

Originally Posted by Greg Reimer 7376

Got a good question. Got a '90 GMC 2500 Suburban,454,all the towing stuff, just had to put on a new catalytic converter to get it to pass the Cal smog inspection, runs great, but on a cold start up, it goes real rich, black smoke, blubbers all over the place, it takes a mile or so to straighten out.. EGR valve was sticking, replaced that, MAP sensor, the engine coolant temperature switch,(two on this motor-one for the temp gauge, the other for the engine computer, still little improvement, so, since I feel at home on this forum around fellow motorheads, I thought I'd ask. I understand its not too uncommon a problem.Any tech assistance will be appreciated. Thanks,Greg

Greg, I concur with Mark, converters need an air/fuel mixture that is constantly flip-flopping from lean to rich. If the oxygen sensor is sluggish or dead, the fuel feedback will flip-flop too slowly or remain rich all the time. Will I see you at the Finals this year?