CRAZY Lean under acceleration

[dbritt]

I just installed a 2g MAF, fuel filter, and walbro 255 pump...

Short story:
Installed the MAF, went for test drive, POP POP POP all over the place. Running lean really bad, couldn't make it up a hill hardly. Called my friend up, he said to change the fuel filter, so I did and I also installed the walbro pump I had.

Nothing much has changed, it's not AS bad because I have to be accelarating to get the popping. Before the pump installation it was popping even while just cruising sometimes.

I don't know what the problem is. I understand that very few things are merely install-and-go (with no tuning) but I thought I'd lose a little performance or gas mileage at worst. What should I try in order to fix this problem? TIA

 

[PropXprt]

Did you check for boost leaks? If not www.vfaq.com has a faq on how to do it.

 

[Coldandafraid]

you installed a different air metering device without a pocketlogger and AFC to test and/or calibrate?

 

[Tyler_Baker]

Originally posted by dbritt
I just installed a 2g MAF, fuel filter, and walbro 255 pump...

Short story:
Installed the MAF, went for test drive, POP POP POP all over the place. Running lean really bad, couldn't make it up a hill hardly. Called my friend up, he said to change the fuel filter, so I did and I also installed the walbro pump I had.

Nothing much has changed, it's not AS bad because I have to be accelarating to get the popping. Before the pump installation it was popping even while just cruising sometimes.

I don't know what the problem is. I understand that very few things are merely install-and-go (with no tuning) but I thought I'd lose a little performance or gas mileage at worst. What should I try in order to fix this problem? TIA

You need some sort of fuel control, 2G MAF leans you out 20%, even with that fuel pump over running your regulator you still don't have enough fuel. I drove my car for one week with an AFC, but I had a AFPR set at 44psi with the hose connected, it ran really lean, but drivable. Get and AFC and or 550's. What knock counts are you seeing on your datalogger? Lates...

 

[dbritt]

Originally posted by Coldandafraid
you installed a different air metering device without a pocketlogger and AFC to test and/or calibrate?

I have the TMO datalogger...

 

[dbritt]

Also, I have one CEL, the TPS is shot. I ordered another one off ebay and should be here soon I hope.

I'm wondering if the ECU is being thrown off by the wrong sensor values and is running lean because of that?

 

[dbritt]

Originally posted by PropXprt
Did you check for boost leaks? If not www.vfaq.com has a faq on how to do it.

how would a boost leak cause a car to be LEAN?

 

[dbritt]

Originally posted by Tyler_Baker
You need some sort of fuel control, 2G MAF leans you out 20%, even with that fuel pump over running your regulator you still don't have enough fuel. I drove my car for one week with an AFC, but I had a AFPR set at 44psi with the hose connected, it ran really lean, but drivable. Get and AFC and or 550's. What knock counts are you seeing on your datalogger? Lates...

Datalogger is showing a peak of 22 for knock which occurred twice in a 3 minute test. There were 3 occurrances of 8-12 during that same test. Other than that, knock was next to none.

 

[tsi20gawd]

tps can cause some wierd problems...start w/that and see where you R when thats been taken care of.

best of luck!!

 

[dbritt]

Doing a fuel pump rewire and tuning with the AFC corrected the problem. I need to upgrade to some 550s and new AFPR, but the rewire and AFC is doing the trick for now.

Thanks for the tips.