black98ws6ta

iTrader: (77)

I guess you should go ahead and preach that to every member on the site that has a 450+ rwhp car on a stock fuel system with a single walbro. Or all the nitrous guys that have fuel pressure drop when there bolt on 150 shot drops fuel pressure at the hit. I am not arguing that its best for the fuel pressure to stay perfect, just that a small amount of fuel pressure drop (1-6) is only REALLY a problem when it is inconsistent and you cannot get repeatable good results.



That's a new one for me....02 sensor reading unburnt fuel shows lean.

How about the unburnt air in the exhaust makes it show lean?

HUNTER02SS

iTrader: (24)

Damn dude, no need in getting your panty's in a wad about this. The fact is if you are losing fuel pressure, your pump is not keeping up. It is best for anyone doing any type of mod's to have the correct fuel pump to keep up with the fuel need's of there setup! AND YES, I WILL PREACH THAT!! Plain and simple. A 10psi fuel pressure drop is ALOT, and to much for anybody concerned with there setup to make it correct by fixing that problem first.
As I said about the unburnt fuel, yes it will show lean, but if it is a minimal misfire where you are actually burning some of the fuel, but not 100% of it, it will show a misfire and a rich condition. It happen's!

99CAMMEDSS

iTrader: (3)

Thanks alot for all of the replies guys, it looks like i need to get rid of the racetronix 255 pump, while driving the car has around 61 psi and as soon as it starts to misfire at wot it drops to 50 or less. I was thinking of doing the diy dual walbro 255 pumps, what do yall think of doing that would there be another setup that works good, or is the dual 255 the cheapest that will support the power?

99CAMMEDSS

iTrader: (3)

Well i put Lonnies Performance Camaro/Firebird '99-02 LS1 Double Pumper fuel pumps in which fixed the fuel pressure problem but the car still cuts out at any boost above 6 or so pounds, the guys at dyno lab says that the ignition is cutting out so now im stumped and dont know were to look for the problem, could it be the coils, wiring harness, etc any help would be great!!!!!!!
Thanks

MY99TAWS6

iTrader: (3)

Very strange..Had problems at wot with my car and it was burnt wires. I was gapping at .028 autolite 103 in there currently. Usually its almost always ignition. You have good valve springs too. Baffling. Maybe some coils are bad..truck coil swap might be good idea was thinking to do that on mine at some point in time if start having troubles.Can you borrow coils off fellow broh maybe?
Also maybe take the boost controller out of the equation right now. Run no line to gate and see if you get your desired boost level. Being careful of course.

98Z28CobraKiller

iTrader: (17)

Pressure is created by a restriction. If the injectors are going static and dumping fuel, it will by default cause you to drop pressure. By getting the injectors under control, you will probably get your fuel pressure back. By adding more pump, you may have addressed the wrong problem and made it worse. That's not to say that you should scrap the fuel system. You;ll need it once you get the real problem resolved. Do you have any injector duty cycle data? Are you running closed loop?

99CAMMEDSS

iTrader: (3)

Well i am running speed density closed loop, and im not sure on the duty cycle after i got the fuel pumps in i took it to my tuner to tune it and thought that he could tune for the different pumps, so im not really sure on the tuning aspects of things.

99CAMMEDSS

iTrader: (3)

Ya that was i was going to do is swap some coils in there because the ones i have, do have 120+ thousand miles on them so i guess its worth a try also i will put some fresh wires in there also to see what happens.

99CAMMEDSS

iTrader: (3)

Any body else have any ideas???????

rms-man

iTrader: (11)

Have you considered another tuner?

I was gonna tell you with the pressure drop before the pump upgrade and the sub 10:1 afr that your tune was the problem. Running way too rich and causing it to miss and stumble. Also, it was maxing out your injectors because it was commanding way too much fuel. I've seen this a handful of times tuning boosted vettes.

Bottom line it sounds like you need a accurate WBO2 hooked up and get a accurate tune in there and you will be making big power.

black98ws6ta

iTrader: (77)

I said the same almost 3 months ago. To the OP, any good tuner should be able to help you diagnos this problem. Unless you are turning away his help because of having to pay for it.