1991 Cadillac Brougham Engine Performance

JGROFF05

MEMBER
1991 CADILLAC FLEETWOOD BROUGHAM
V8
2WD
AUTOMATIC
192,000 MILES

My car is fouling spark plugs within a 4 month period of replacing them and I have upgraded the heat of the plugs to burn hotter. The plugs are black and soot covered and they can be cleaned and reused but my issue lies in it fouling them. I ran a compression test to see if the piston rings were bad and all of my cylinders were at 195 and 200 which is close to the 9 to 1 ratio they need to be. My valve seals are not bad and I do not get blue smoke at all so they are fine. I changed the pcv valve to see if it was causing pressure in the crankcase and I am unsure of the result. I was thinking it may be running rich cause the spark plugs get carbon fouled and not oil fouled. I have changed many sensors but the only two I have left are the MAP sensor and the fuel pressure regulator. Any help is appreciated. I thought they were oil fouled plugs but they are getting carbon fouled.

1 Reply

2CARPRO JACK

MECHANIC
11,533 POSTS

Either one of the two sensors you havent changed can cause a rich condition. Both of those are used directly for fuel enrichment. The pressure regulator is mechanical while the MAP is electronic. Use a mechanical fuel pressure gauge to see what the pressure is. If the pressure jumps a few pounds when you rev the engine it the reg is probably good. If pressure stays when reving, the reg is bad.