I have a 1991 Trans Am with a 350 TPI with SLP headers, no cats, flowmaster and AFPR, 3:23 gears.

My dad has a 1991 Z28 with a 350 TPI and 3:23 gears and his car is bone stock.

Well his car is alot stronger and faster than my car and I have those mods and his is stock. Also my car drinks alot more gas than his and my car is running rich, puts out black smoke sometimes and you can smell it.

I hooked a computer up to it and it says nothing is wrong with my motor, says everything is working fine and my car is running LEAN.

I ran some injector cleaner through it and while I had it idled up to 1500 while running it through I noticed the motor wasnt smooth running, it was kinda rough.

What could be causing my car to be running so bad and alot slower than my dads?

Also my motors timing is set at 8. Is this ok and could it be causing my problems?

 

whats ur fuel pressure set at?

 

His is a camaro.. they just have the edge.. sorrry.. j/k..

Lean or Rich.. either way.. you are gonna be slower.. with the black smoke i would thing way rich like you.. to rich is going to take away a lot of power.. these cars like to be about 12.5-13.1 A/F ratio..

You gott a dyno in town? Do they have the unit used to check the A/F? Thats your best bet.. get it on there and play with the AFPR until you get it around 12.5-13.1 across the rpm's and you are sure to see a nice gain..

of course.. always make sure the car is tuned up well.. no bad wires or plugs..

make sure all those header bolts are tight and not loose and causing a leak.. clean those air filters..

last thing to look at.. how many miles on each..? Whats the temperature getting at on each.. if his is staying around 180-195 and yours is going to 210-215.. a simple thing like that can give him a nice edge on you.. if you have a lot more miles and you've got a nice build up of carbon in the engine and intake.. that could be a factor too.. whats the weight difference.. etc.. my point is.. its not always the engine or tune-up...

 

My fuel pressure is set at 46.

 

My Fuel pressure is set at 46 when i put a gauge on it. Should I bump it down?

Also his car always runs about 220 or so and mine runs around 180. My car stays cooler than his.

Also his car has 55,000 original miles on it and mine has right at 99,000 original miles.

 

TTT

 

I think stock pressure is around 42.. but you really do not want to go down fast.. bump it down to 45 and see what happens
Then 44.. if you don't have a place to dyno.. go to the track one day and just start at 42 and keep increasing little by little as you should get a little faster and once you start getting slower bump it back to the previous setting.

 

Before you do anything else, check the resistance of your injectors. If it still has the originals, they are Rochester Multec's and they have a history of failure. They should test around 14 to 16 ohms. If any are less than that, the coils in them have begun to short out and that will cause the engine to run rich.

 

1) Is this with or without the vacuum line connected to the FPR?
2) You said that the computer indicated it was running lean. Be more specific, what exact data did it give you?
3) Black smoke is SERIOUSLY rich. We are talking below 10:1. You are losing SERIOUS power due to how rich it is running.
4) When is the last time the plugs, cap/rotor, and wires have been changed?

Tim

 

46 is with the vacuum line disconnected

all th mechanic shop told me is it was showing it was running lean. they said nothing else. Ill try to go bck by there and get more info.

its not alot of black smoke but i have noticed a little

I have no clue when the last time those things have been changed

 

Keep in mind the butt dyno can lie.

Changing the spark at the track. I went from 14.2 to 14.0... and it felt considerably slower on the 14.0 passes.

 

The first thing to do is a complete tune up. It eliminates a lot of questions all at once. When did you get the headers - make sure those bolts are torqued up. If you do nothing else - check out your ignition system. I was losing 3 - 4 tenths when I first got my 350TPI because the wires, plugs, cap and rotor all needed replacement!

 

Amen.

Tim