Trying to figure out what's wrong - help
 

I need some help here. I went to the track yesterday. Temp was 89. Last week I changed the plugs. Put TR-6's in. When i lauch the car, it runs good through 1st, 2nd & 3rd. When I go to 4th, it seems like the car is running out of gas coming to the traps and through the traps. I'm just hitting the shift light coming on at 6800 rmp. You could just feel there was nothing there, like it was boiling the gas or not getting enough gas. When hitting the shift light in 1st, 2nd and third it felt fine, but then after hitting fourth and heading toward the traps, it really strained. Could that be the plugs? I am still running stock injectors. Could it be injectors? Best run today was 12.26 at 115. Most of the day was like 12.49-12.61 at like 113. Can anybody give me any ideas as to what this could be?

Can somebody give a little help here!

Lets see if I can help some.

Assumption: your car has been professionally tuned?

If so, than they should have mentioned the injectors. IMO you are running out of injectors. I'll bet your duty cycle has to be close to 100%. In my car's previous life, h/c, stock bottom end, etc, etc. I had to move up to the SVO 30lb (which is like 36lb for our cars). I 'THINK' you'll find an injector duty cycle calculator in the sticky at top of this page. I have never been a big fan of Granitelli MAS also. Always use the stocker.

David

Thank you very much, yes the car was professionally tuned. I did look at that injector cycle calculator and it was pretty much right what you said, 30lb. As far as the Granitelli MAS, if I went back to the stocker, I think I would have to have it tuned again as when I put it on it ran bad until I had it tuned. Wouldn't it go the other way if I switched back to the stocker without the tune? Thanks again.

do you have a Fuel pressure gauge?

I did until I tried to change the plugs. I had a fuel pressure isolator coming off of the fuel line to run the guage into the car. It got so much in the way of changing the #3 & #5 plugs and it vibrated so much inside the car that I took it off just over a week ago. I do have one at the end of the fuel rail also. I looked at that between races and it's sitting right on 50 lbs at idle and goes up to 55-60 when reving the engine.

how old is the fuel filter?
can you throw the Gauge back on quickly and make a pass?

I think I changed the fuel filter last summer, only has about 3 or 4000 miles on it if that. It's a giant pain the the ass to put that guage back in. It has the isolator that has a hose run up through the inside of the car under the dash from the engine compartment. You thinking it's fuel pressure? What do you think of going to th TR-6 that I did and what do you think about the fuel injectors? Thanks

For anybody who wants to know, probably aren't any, I found out what the problem was today. We went back to the track today. Temp in Lapeer was like 54. Car ran like a raped ape. Finally got into the 11's. Ran 11.82, no problems with fuel. It was the heat.