Weird problem with Air fuel.....

[RacerXJ220]

During WOT I have been experiencing a random lean condition.

I think my FPR is taking a crap on me, just want to ask you guys.

Normally, my AF's should be in the 11.5-12.0 region for 11PSI. Well tonight it wanted to go to 13.0-13.5, I started losing power, checked the AF and let out of the gas.

During brake boosting is where I experienced this most. My FP at idle is 43PSI with no vacuum attached. I hope it didn't do any damage, everything seems ok.

I am using a Magnafuel 625 pump, dual -6 into the rail, single -6 return. It's been running awesome until tonight when this happened.

I thought I might need a new tune, but a few pulls later, all is well and AF's are where they should be.

Thanks for looking.

J

 

[Tura_1JZ]

What computer setup are you running? what brand is your fpr?

 

[RacerXJ220]

Stinger 4424, not sure what brand FPR. Had it on the car for about four years now. Worked great on the dyno, been fine until last night. I haven't changed anything on the car except for the Magnafuel, that was weeks ago.

 

[RacerXJ220]

If the FPR is cold, will it work the same as it will when it's warm? I heard that can have an effect on the idle, not sure about WOT...

 

[Supracentral]

I haven't changed anything on the car except for the Magnafuel, that was weeks ago.

I'd start with the wiring that leads to this pump. Most recent component change is the likely suspect 9 times out of 10. How are you powering this pump? Home run from the battery with a big fuse & a relay, or are you relying on the stock wiring?

Do you have a fuel pressure gauge? Rigging up an electric fuel pressure gauge so you can see fuel pressure when this is happening.

 

[RacerXJ220]

I'd start with the wiring that leads to this pump. Most recent component change is the likely suspect 9 times out of 10. How are you powering this pump? Home run from the battery with a big fuse & a relay, or are you relying on the stock wiring?

Do you have a fuel pressure gauge? Rigging up an electric fuel pressure gauge so you can see fuel pressure when this is happening.

I am on 10 gauge wire off the battery, 20A fuse and 40A relay. 10 gauge ground was sanded to ensure good contact. Stock wires for a pump this size would look like rappelling off a cliff with dental floss.

I am going to move some things around on my 3 pod pillar mount and make room for the electronic gauge this week. I'll be keeping an eye on this from now on.

After the period of leanness, it ran fine when I did normal 3,000-7500 WOT pulls.

Last night I tried to recreate the lean condition, but "normal" driving doesn't cause it. It seems to happen only AFTER I brake boost and try to go through a pull.

I was on half a tank of gas, never below 1/4, and my tank is sumped from the drain plug to -10 feed thru -10 aeromotive filter, then through a magnafuel filter on the other side of the pump.

That's all the info on it. I do appreciate the suggestions here.

Thanks again.

J