Leaning out high RPM

[LZeppelin513]

A few other questions... How are you tuning this car? OBDII or OBDI? Also what is the injector flow rate set for? And what do the 3500 injectors flow? If this is an OBDII car you will not see huge fuel changes with screwing with the VE, you mostly see that in adjusting the MAF table, but it really sounds like this setup is starving on fuel flow somewhere and is not a tuning problem. I guess you can ignore my first statement since this is a return less system, the FPR wouldn't drop pressure off like a return type system so it would have to be something up in the tank.

obd1 $A1

Well the FPR still returns fuel just not the injector rails. So flow goes from pump to FPR via braided AN 8. some fuel goes to rail via braided AN 8. excess goes back to tank via braided AN 6. Pressure is set to I think 55 PSI and goes up to around 60 when I rev it up.

[LZeppelin513]

wow, dropping down to a commanded 5.7 AFR.....

i think i see your problem though. at that 5.7:1 point, the injector duty cycle is 193%...... that's why you're not seeing more fuel flow.

you're at 80% at sample # 162.

I knew I was getting close or going over 100 % but I wanted to make sure it was not a tuning issue and just lack of fuel for some other reason.

How do you calculate injector duty cycle?

I was thinking divide rpm by 60,000 to get revs per millisec. Our engine with batch fire will fire a bank 1.5 times per rev right? So now mult by 1.5 to get time between injector fire per rev. Take pulse width in ms and divide by the calculated number to get duty cycle.. I must be thinking about it wrong because that doesnt spit out correct duty cycle numbers for me.

anyway, its obviously not limited by the tune since my injectors are basically wide open, right?

[LZeppelin513]

Could be bad check valve or bad pressure regulator... Get a pressure gauge on it when at WOT and see what it's doing. I'd also check all lines including pump to pickup in the tank and ensure nothing is kinked or leaking somehow... Lower flow could also cause this issue.

whats the best way to monitor fuel pressure at wot? run a rubber line up and out of the engine bay, connect it to my gauge, and tape it to the rear glass?

[LZeppelin513]

can you post up your current bin file?


The pump should not lose it's prime, that's usually a sign that the check valve isn't working in it.


I've attached an older .ads file (just remove the ".xdf", couldn't upload otherwise). You can just load it in and view your logs w/o all the extra info that may cause confusion.

Sure: https://docs.google.com/open?id=0B5P...FVMLTFTekFLQ28

A faulty check valve wouldnt be able to cause low fuel at high rpm, right? So the check valve may be bad but unrelated to the lean condition.

thanks for the .ads that will be helpful.

[3400-95-Modified]

A few other questions... How are you tuning this car? OBDII or OBDI? Also what is the injector flow rate set for? And what do the 3500 injectors flow? If this is an OBDII car you will not see huge fuel changes with screwing with the VE, you mostly see that in adjusting the MAF table, but it really sounds like this setup is starving on fuel flow somewhere and is not a tuning problem. I guess you can ignore my first statement since this is a return less system, the FPR wouldn't drop pressure off like a return type system so it would have to be something up in the tank.

[robertisaar]

wow, dropping down to a commanded 5.7 AFR.....

i think i see your problem though. at that 5.7:1 point, the injector duty cycle is 193%...... that's why you're not seeing more fuel flow.

you're at 80% at sample # 162.

[3400-95-Modified]

Could be bad check valve or bad pressure regulator... Get a pressure gauge on it when at WOT and see what it's doing. I'd also check all lines including pump to pickup in the tank and ensure nothing is kinked or leaking somehow... Lower flow could also cause this issue.

[Superdave]

can you post up your current bin file?


The pump should not lose it's prime, that's usually a sign that the check valve isn't working in it.


I've attached an older .ads file (just remove the ".xdf", couldn't upload otherwise). You can just load it in and view your logs w/o all the extra info that may cause confusion.

[LZeppelin513]

One thing I thought of; after my fuel pump primes, it very quickly drops back down to zero psi. I think it has done this since the beginning with this swap. A possible cause for this could be that the diaphragm in the FPR is not seated properly and fuel is passing back the return line. This could cause my lean condition at high RPM right??

When I get a chance I am going to clamp off the return line to confirm its the fpr bleeding back.

[LZeppelin513]

I am leaning out to over 13 AFR above 5000 RPMs.

I have a new (last year) high flow TRE fuel pump. It is hot wired to get its own power circuit from the battery for minimal voltage drop.
That goes to an aeromotive FPR (http://aeromotiveinc.com/products-pa...ass-regulator/).
Then I run return-less to stock 3500 fuel rail and injectors.

I have a mechanical guage on the regulator and it stays solid when revved but I cant watch it when driving.

Fuel filter is about a year old.

I kept increasing fuel by PE table and VE table but was getting diminishing returns in upper RPMs.

Here is a datalog run up to 5000. Above 5000 it just gets leaner. WOT is on pg 6.

https://docs.google.com/open?id=0B5PFNNInFEsbeUFmNTU0Ri1KOFE

Whats most likely going on? Is the "final BPW" the ACTUAL BPW of the injector, or a calculation? From the data it looks like no matter how long it opens, no extra fuel is being delivered.
This makes me think the fuel pump is not up to the task, but that seems weird as the pump is new, works, and is rated way higher.

Also, this is not a new problem, I just haven't been driving up in high RPM range to discover this.



Update: problem fixed, pg 3 for solution