Hey guys, working on my 87' gxl with t2 swap and haltech e6k. Alternator died the other day an left me stranded out at a friends house. Got it home and replaced with a good one. Charges at 13.4 volts from alt. Take it out for a drive and notice its running lean. My setup consists of:

E6k
550/1600 injectors
3 bar map
Walbro 255
Glowshift wideband
3" DP to 2 1/2 straight exhaust
S5 turbo at 8psi(wastgate ported)

A/fs are lean even at idle. And at WOT. Basically lean throughout the rpm range. I checked voltage at the pump and the highest i got was 12.8. It holds ~41 to 42psi at idle. Drops to 40psi when i hit pedal and holds all the way to 6k. Is that enough voltage to my fuel pump? I was reading and seeing it should be 13.5-14.0 volts. I've already swapped both primary injectors being that its lean at idle too, i was hoping that might change something but it didnt. Any ideas guys? I have no vacuum leaks, fuel pump re wire, runs off e6k relay, no fuel leaks, fuel filter has maybe 300 miles on it. Im thinking low voltage to pump or low voltage from the alt? but would like a second opinion. Thanks!

 

there is a battery voltage vs injector lag map so if the voltage was different between the old alt and the new one, maybe this is off, and causing it to run a different AFR.

13.4v is ok, but not great. new should be right around 14v

 

You are right. I totally forgot that i was running a s5 alt before and the one i recently put on was s4. The s4 alt was sending 13.7 to the battery before i put another good s5 alt on just a little bit ago. Now it's sending 14.0v at 1k rpm and up to 15v in high rpm with no fans on or lights. Fuel pump voltage jumped back up to 13.4 at idle. But a/fs stayed the same. Leaner than usual. And i drove it and its still lean at wot. Even at 2psi the a/f is at ~14.0 and doesn't richen up. Could maybe my ecu reset to a stock map? I didnt think so because i figured it would richen like crazy cause of my 1600cc secondaries.. Idk, it's bugging me lol. I appreciate your help though.

 

Impossible.

How long have you had it running? I would suspect the battery comp map as well, as J9 suggested. I'd also look at air temp compensation. If the weather is drastically different than when you last ran the car, this map not being properly setup will cause issues.

 

The car was tuned in Aug of this year by Steve Kan. It's was in a 100* shop in Cali. Have had 0 problems for the last 4 months up untill my alt died and it snowed here. So yes, weather did take a dramatic turn. It got down to 2* here. When the alt died it was about 15* outside. I do keep my car garaged though. I'm still a newb with the haltech. But it seems simple enough to figure out..appreciate the info too.

 

they only do what the ECU tells them to do, which is the part you are in charge of…

 

Ya, i understand that. I'm just confused on why im running lean. I've been reading my manual on how to adjust AIT map and voltage map. But afraid to actually make a change cause i dont wanna make it worse. I drove it a few times before the alt died and it ran fine. I'm still very new to the tuning world. And I'd hate to ruin a good motor lol. Any advice is much appreciated.

 

Have you calibrated your wideband since the alt failure?

 

Yes, twice. Read the same after both re-calibrations. I know its not a false reading because of the hesitation i get when boost comes on.