Hey guys and gals, I need some input on an issue I've been wracking my brain over. Here's the back story:
The car is a 95 civic with a GSR swap. It's been running fine for over a year. A while back I noticed the AFRs were going a bit lean but nothing too extreme. Then I ran through a large puddle (caught in a monsoon, common here in AZ). The car died, so I cleaned the plugs and wires, started it up and limped it home. The AFR's were really lean but it was only a block or so from home. I decided it was time so I put new plugs, cap and rotor in it since I was sure that they had gotten wet. Started it up and saw the AFR's were still super lean and the car was stumbling really bad. I was using an AEM adjustable FPR but I never liked the thing because I suspected it was leaking by as the fuel pressure would drop off really fast when the fuel pump (Walbro 255) wasn't running. I stuck a new Aeromotive FPR on there and the car refused to start at all. Playing around with it, I bumped the fuel pressure up to 60psi and it started for me. I pulled the injectors (RC750's), cleaned and bench tested them and checked all the wiring from injector clips to ECU. Everything was good to go, so I dropped the pressure back down to 45 and increased my start fuel (AEM 30-6040). Car starts fine now but still goes lean after leaving cold idle. I decided at this point to change the fuel pump with an Aeromotive Stealth 340. Same result. So, I figured I'd log on here and see if anyone has any insight.. I'm tired of talking to myself about this.

 

fuel filter?

 

CEL codes?

 

The fuel filter is a brand new AEM cartridge type filter and is good to go.

I'm running the AEM series 2 ECU, so there are no codes.

Thanks for responding, guys. I'm going to pull the fuel pump today and check to see if the fuel sock/strainer is collapsing on it's self when the pump comes on and causing a partial blockage. It's about the only thing I can think of.
Any other ideas?

 

Do you mean that you checked for fault codes and there are none or that you haven't checked for codes?

 

AEM V2 with no type of CEL codes? That would be one fucked up as stand alone solution. How are are you going to know if there is a failure or not?

 

Unless you guys know something that I don't, the AEM S2 box doesn't have CEL functionality.
Update on the car, I apparently got a bad fuel pump from Summit. I have to call them and see what they can do for me. After about 3 minutes of running, the pump started "squealing" loud enough to be heard outside the car and over the full 3" turbo-back catless exhaust.

 

As far as I can tell, the AEM S2 ECU can report fault codes. Contact the company for details.

 

I had that happen with an Airtex unit. Bad pump. Brand new. Last one they had.

This is why folks say to not buy aftermarket stuff.

 

airtex is aftermarket oem. op needs a higher flowing pump due to his motor setup. oem is not really an option there.

 

Update: Summit sent me a new pump really quick and I installed it yesterday. I set fuel pressure and started the car. Idles like a champ. Well, it did at first. Once it gets to operating temp, if I blip the throttle, idle jumps up to 2K+ rpm and starts surging. I'm gonna pull the IACV and the FITV and see what's up.

 

You able to data log sensor activity while this surge is happening?

 

I was looking at the feedback while it was happening and there were no indications that anything was amiss. (since the FITV is not electrically controlled, I was, correctly, more suspicious of it that the IACV)

Update: Cleaned the FITV and IACV. Surge is gone and the car seems to be running fine other than the fuel map being out of whack, which I expected it to be with a new fuel pump and FPR.

Lessons learned. It's not very typical for multiple failures to happen simultaneously but it doesn't mean that they can't occur. It's good to have a sounding board to take you out of your own head when troubleshooting. Regardless of whether people's input is helpful or not it can get you thinking about things in a different light. Thanks guys.

 

Good stuff, happy boosting!