camar0corey

iTrader: (22)

Is there a way to lean out a TBI motor? Car is my Moms 91 Firebird, its a rebuilt 305 TBI with a mild cam, didn't put it together so I don't know cam specs or anything, but the car runs ridiculously rich. Used to have a carb on it was told by the guy we bought it from, don't know why he swapped it back to TBI, but its so rich its retarded. Not sure what was originally in the car, don't know if its a fuel pump for a TBI, carb, or TPI.

camar0corey

iTrader: (22)

Nobody?

8a8mfh

iTrader: (3)

Whats the fuel pressure?
Trying not to write a book here so give as much info as you can.
A month ago I built a mild TBI 454 and burned chips, etc. I can help if you provide some specs.

edcmat-l1

iTrader: (10)

You can burn a chip for it, or buy one from a mail order tuner. Its basically just a SD setup. Map sensor, no MAF. It can be leaned. The VE table needs to be tweaked. Same **** with any EFI car with a cam, just different equipment and tuning software.
But to answer your question, yes, it can be done.

JPATI

iTrader: (1)

Fuel psi should be between 9-14psi. The problem is probably low vaccum to the MAP sensor.check this first.(maybe vaccum going straight to EGR or EGR stuck open,you don't want vaccum going to EGR at idle). If EGR is ok, Look for vaccum leaks. If none, then the cam is the problem. Take a vaccum reading. 17-20"HG is stock. If it is less than 15" then the cam needs to be swapped. the low vaccum is making the MAP sensor reading low. The PCM thinks the car is under aload when it is notand shooting the extra fual to it.. You can get a handheld vaccum pump and hook it straight to the MAP. When the car starts pull about 18"hg of vaccum and see if it helps the idle.

Also check the ECT and O2..they can also cause a rich condition.

01WS6/tamu

iTrader: (37)

If you can still find them. Back in the day when we used to hot rod the TBI chevy engines you could buy an adjustable MAP sensor and get a chip burned. Between the two you could get it close to right. With a large cam it would have a nasty idle surge followed by either rich or lean.

camar0corey

iTrader: (22)

Thanks guys, I'll look into some of these items.

What the fuel pressure difference between a TBI and a carb? If the TBI pressure is higher, can I use a adj. fuel pressure regulator to bring the pressure to a carb friendly level?

I wish I had the cam specs, would probably be easier to get a chip burned then, but have no idea on specs, was just told its a small cam. It sounds nice, but the acceleration is just plain sad and the exhaust clouds are not the greatest thing.

If I have some time tommarow I will go grab a fuel pressure gauge and see if I can get a idea on that, I take it there is a port somewhere? I haven't looked at it much, besides running rich the car has been trouble free and gets my mom back and forth to work.

Drumer919

iTrader: (2)

TBI fuel pressure is 9-15PSI, carb pressure is ~6PSI, yes if you had a carb with a TBI pump you could regulate it down.

On my TBI truck there is no FP test port, You need an adapter to go between the fuel line and the inlet on the TB with a test port.