1998 Chevy Tahoe Po1o2/ P0304

GREENONE

MEMBER
1998 CHEVROLET TAHOE
6 CYL
4WD
AUTOMATIC
128,000 MILES

Engine is still in one piece. Much appreciated rasmataz. Now I can get back to solving the original problem, which is that I get a rough idle when I'm on the brake pedal and shifted into drive at a stop sign. The engine seems to run smoothly at all other conditions. I do get a P0102 MAF, which I have cleaned. I also get a P0304 misfire but I have now replaced the spark plugs, wires, cap, rotor, distributor, #4 plug again, #4 wire again, used throttle body cleaner on the throttle body and the EGR valve. I'm beginning to think I have an injector problem, or a spider problem, or maybe a vacuum leak? Any ideas?

1 Reply

MHPAUTOS

MECHANIC
31,937 POSTS

HI there,

If you are getting a rough idle with the brakes applied I would be suspecting a leaking brake booster(vacuum leak) Disconnect the booster vacuum line and plug it, with no vacuum to the booster see if it still runs rough with the brakes on, if not you will have a booster problem, start here.

Mark (mhpautos)