TBI running rich

[chevyguybc]

hey all, Ive put 4,500kms on the truck since I did the clutch and got it running.

It has headers and dual 2.5 inch mandrel out the back, no cats, k&n filter with airstream top.

Im pretty sure it is not chipped, but yah never know, it did tow alot in its day i think because the rear is sagged. Anyways...

It seems to run rich, what sensor causes this?

 

[dyeager535]

Why do you think it runs rich? Need some symptoms. Mileage, trouble codes, etc.

Your check engine light work?

 

[chevyguybc]

the check engine light works, It was on one day, so i pulled the fuses and reset everything, and it hasnt come back yet...


sypmtoms are, smell of raw gas...fuel mileage poor with stock street tires and 3:42s, 4 speed, its a rebuilt motor i think, rv cam i think...

 

[dyeager535]

All ignition components in good shape? Good inspection done for vacuum leaks, to include TBI base gasket? Inspection of engine bay doens't reveal any broken or burnt wires?

If all yes, and vacuum leaks are for sure not a problem, how is idle both at startup and warmed up?

 

[chevyguybc]

im pretty sure the tbi base gasket is a suspect, causing more air to be brought in,

at idle its fine, but if u let it idle for longer then 5 mins , it goes up and down VERY slightly..... other then that it runs like a champ...

the spark plug wires could be replaced too? should I go with msd? or does it matter..

 

[dyeager535]

IMO on plug wires, get what you can afford. Most of the claims of power are hype (as is to be expected from anything being marketed) however quality insulation and boots WILL last longer, which over the long run will result in better performance over stuff that has deteriorated sooner.

MSD wires seem to be pretty well regarded. I've got some Accel wires on my setup (going on 5 years or so now) that I've had no problems with, but I know they haven't the best record with others. I would have been comfortable using some lifetime chain auto parts store cheapies had they been lying around. But with headers I'd be keeping a much closer eye on them.