Request: Detailed explination on how fuel delivery works.

[lyfeworx976]

Hey Guys,

Im wondering if anyone knows exactly how the fuel delivery system works? Im having a huge problem running lean at full throttle. I don't have a SAFC yet, but here is the problem.

I run a 18g turbo, only at 8 psi (for now) with a supra fuel pump, new fuel filter, rewired fuel pump. and 550 injectors with a MAF translator.

Okie now for the problem.

No matter if im using the stock fuel pump or the supra fuel pump the same fuel preasure is getting through, wierd eH? The low and mid are fine, the high is just very lean. You would think running 550's and 8psi with a huge fuel pump I should be spitting out lots of black smoke from running so rich, but im not im lean!

ALso the DC of the injectors are WOT i belive are 82%, which should flow more then enough for 8psi.

If someone could give me a explination on how the fuel system works so I can try to problem solve this.

Im running a stock 1g FPR btw, but have recently replaced it.

I do however notice i have a new o2 sensor, but its not OEM, its hardwired? Could this be a problem?

If you have any clue on a problem, or something that would control the fuel at high let me know.

Thanks,

Michael

I need to solve this before I can treat my knock problem.

Thanks!

The logger is how im getting my information.

 

[kpt4321]

How do you know that you are lean?

Do you have an in-car fuel pressure gauge?

 

[lyfeworx976]

Im using the pocketlogger on the fuel trims i can see.

thsi is part of my problem im not sure how it all works. EGT are fine though *SHRUG*

Im wondering about my o2 sensor, cause its not OEM. its hardwired.

 

[kpt4321]

As I said. What is it that makes you think you are lean under boost?

What does the logger say?

http://www.vfaq.com/TMO/

 

[talon1979]

We need to know something like your car is seeing 20 counts of knock at 5k rpm and you are getting 9 degrees of timing, and your o2's are at .80. Just knowing that your high fuel trim is above 100% doesn't help much.

550's w/ a supra fuel pump should have no problem giving enough fuel to an 18g turbo. We need to know more things to diagnose your problem.

 

[lyfeworx976]

ok at about 4th gear, the o2's go to .02 and the timing is at 20, they just take a huge drop all of a suddon.

 

[kpt4321]

BE MORE SPECIFIC!

Does the knock go up? Does the timing change? Does the car stutter, stumble, pop, backfire? What rpm?

Just post the damn log.

It's difficult enough to diagnose problems over the internet; it's quite a bit harder when you say "my car does bad stuff, how do I fix it?"

 

[crankbender]

kpt i know what you mean... He isn't getting on you it is just really hard to guess without information.

 

[lyfeworx976]

In my other post is the log. I got in trouble for doing cross posting. So I will have to upload the log when I get home. Its in another post though.