May 7, 2009 Trip to the track, Help?

[Krazykid]

Ok guys, so I am new to drag racing so go easy. I am currently running the Great McRat Racing tune. Last week was the first week with this tune and truck did great ET's between 8.4-9.1. I know this week I was going to work on my 60' times to get a little better but with the truck running the same tune it ran like dog crap. (changes for this week.) tire pressure down front and rear 5#'s. (32f/26R) the big problem I was having is about 3/4 track the truck just felt like it quit going. I have attached the file of the last pass, could I please get some insight on what is happening?

 

[TrentNell]

your rail pressure was a bit low at the beginning ( 20.5k-21k) and then when you hit 4th gear it tanked to 9k . another thing mm3 was at 90 most of the run and real jumpy up to 115 or so ? may not be getting full pulse width @ 90 mm3 depending on tune .

 

[Krazykid]

your rail pressure was a bit low at the beginning ( 20.5k-21k) and then when you hit 4th gear it tanked to 9k . another thing mm3 was at 90 most of the run and real jumpy up to 115 or so ? may not be getting full pulse width @ 90 mm3 depending on tune .

Thanks for the input. Now you mention it, that's about where the truck felt like it fell on it's face was the shift from thrid to fourth. I do have the PPE lift pump running, also I have not seen any codes. Usually I would seem a P1093 I think is the low fuel rail pressure right? How can I fix it? and What would have caused it to be different from last week. (sorry just thinking out loud.)

 

[Kat]

Is your truck shimmed or a race valve? I can't remember. If it isn't do it. LLY's must have it done.

 

[Kat]

Is your truck shimmed or a race valve? I can't remember. If it isn't do it. LLY's must have it done.

OK you have it... But, did you install it yet?....:grd:

 

[TrentNell]

OK you have it... But, did you install it yet?....:grd:

that would deff explain it even a dirty fuel filter or weak cp3 wouldnt draw down that low so sudden IMOP .

 

[Krazykid]

Thanks guys. I knew someone here would have a better answer for WTF has happening! Just bummed me out after having a good week last week.

 

[Krazykid]

Ok got he Shim Kit and Port rail fitting in today. Just driving it on the road I still feel it surging, however that is without the fuel pump running. Would a fuel filter with less than three months and 3500miles on it really effet the rail pressures? Also just a side not I did not do anything tot he passenger side rail fitting as I have read some people have opened it a little. Any ideas, or should I just hold off till next thursday's Race and log a few runs? Thanks again to everyone for thier support and help!

 

[TrentNell]

Ok got he Shim Kit and Port rail fitting in today. Just driving it on the road I still feel it surging, however that is without the fuel pump running. Would a fuel filter with less than three months and 3500miles on it really effet the rail pressures? Also just a side not I did not do anything tot he passenger side rail fitting as I have read some people have opened it a little. Any ideas, or should I just hold off till next thursday's Race and log a few runs? Thanks again to everyone for thier support and help!

log another run so you can get it figured out before next race .turn on the lift pump , and a new filter is cheap insurance during racing i only run a filter 1 month or so just because it has bit me before .

 

[Krazykid]

log another run so you can get it figured out before next race .turn on the lift pump , and a new filter is cheap insurance during racing i only run a filter 1 month or so just because it has bit me before .

Trent,
Thanks for your continued advice. I will stop by the auto parts store today and get a filter. I will try to log a few short launches on the street this weekend.