Need Help Please... Runs Lean For No Reason

[Draconis]

Okay, this has been going on for a couple weeks and during this time I havent figured anything out nor any pattern.

I'll be driving like normal... not boosting or anything. I guess you can say like 40 mph or something. Then all of a sudden it will run lean for no reason and of course there's a loss of power. It usually catches itself. Sometimes it takes a second or two but then back to normal. Worst case is that it loses all power so I pull into a parking lot, leave the car in neutral and it catches back to normal.

Here's what happened today. I was driving and down shifted to second, came to a rolling stop then started up again. As I started up from my rolling stop there was a bit of hesitation then it was ok. About 20 feet away it did the same thing... this time I pulled over and shifted to neutral but it died by the time I did this. I started up and everything was ok. I drove for about four blocks and the thing runs lean again. I step on the gas a little and it only does worse by making the car jerk. So as the car rolls, I drop the car to neutral and suddenly and my AEM Uego immediately swings to rich. I shift back to gear and it is fine then dies shortly after being too rich... I think it was too rich... I didnt catch the reading on the Uego for I was in traffic. It died so I just turned the key to off then started up the car and it was fine the rest of the way without issue.

I have changed out the O2 sensor a couple days ago. I changed the fuel filter in August.

I have a RB20DET with stock ecu. Plazmaman intake plenum, HKS SSQV Bov, Tomei 256/8.5 lift cams, top mount stainless steel exhaust mani, T3/T04e, Tial wastegate 38mm, FMIC, stock injectors, Splitfire coils packs, Greddy Type S boost controller (off) and a Neo (+4% on high boost at 6000rpm and up).

Any ideas? Like I said before, it doesnt happen all the time. I drove to work and there was no problem. The temp. when this happens varies... no rain or moisture coming down. I am confused.

Thanks.

[Jmaac]

Dont quote me but it kinda sounds like your CAS is dying??

[MBS206]

Check connections on the fuel pump too.

And check injector connections

[blind_elk]

It is never "for no reason".

Sounds like the fuel pump might be on its last legs - do you have a fuel pressure gauge hooked up?

[tacker]

blocked fuel filter easy place to start

[Draconis]

What's a CAS and no I dont have a fuel pressure gauge... I think that will be my next thing to buy.

[l0WRB]

crank angel sensor its on the front of your cam covers, looks silver and stuff has a plug that goes into it:)

[Strik3r]

AFM.. its always the AFM if you can borrow one to test, great, else search this forum for "+solder +afm" and have a go at self-repairing.

[race_snooze]

stock ECU... you should get it remapped

[R32_Matt]

id probably look at getting bigger injectors and fuel pump with the retune as well.

as for the problem, afm, fuel pump and fuel filter are the first things that i would look at

[Adriano]

stock ECU... you should get it remapped

It wont be the ecu, Fuel pump, CAS, AFM, also check for boost/vac leaks, but ill bet its one of the first three, i would also get a recirc BOV

[TTT]

start by cleaning the AFM

go for test drive.

if it's fixed, leave it.

if it's still doing it, take it back off and SOLDER it like mentoined.

You will find a HOW TO guide in the DIY section.