Joel5.0

I know your basing your lean concern on the spark plugs reading, but have you checked what the EEC-IV is reading?....any lean codes registered by the system (41 & 91)?......

90Mustangfan

for me I would check you hego ground wire, that sometimes fixes code 41/91 or running lean issues, its the most overlook thing, that likley is what the problem is, its the orange wire thats in your fuel system harness, its a orange wire, and should be grounded on the firewall, double check that, that can cause alot of issues with it running lean, and with 41/91 problems, Ive was chasing those codes for 6months and fixed it by the ground wire not being hooked up, now i recently started to get the stupid 41/91 codes....IM lost now.

50mikey

I know people always say bump up your FP to get more fuel and all that, but thats not the case. more fuel pressure just allows the injectors to keep up with the fuel pump when adding more hp. The computer is only going to allow the set amount of fuel its programmed for in the EEC. Stock is trying to keep a steady 14.5AF ration I believe. granted im not saying you could have it set at 20 and youll be fine, thats not the case. 39psi should be just fine for 24#s I checked all this on the dyno, ranging FP psi from 30 to 50, once it hit 35psi and more there was no change in AF ratio, in any of the rpms.

If it is running lean you might have an O2 sensor going bad giving your computer some false readings, I dont know if that will always show up on the code reader or not

Tims 88GT

i dont get a lean code but they just look lean.

grabbem88

my idle is 11.0 at idle...should i be worried?......tim i thought we got this straightened out?...mines at 42psi...if that helps on idea's


you need to see if underload does the fuel pressure drop any?...

Tims 88GT

i could not tell u if the fp drops under a load the gauge is in the engine bay. i thought i had it fixed but it looks like i dont. also the car runs a lot and i mean a lot better at night then in the middle of the day. i did bump FP to 41 but i can not feel any differance.

Joel5.0

Have you checked your ACT lately?...even if the system doesn't throw a code failure for it, the sludge buildup it is exposed to, will cause the ACT to register higher temps than the actual ones (leaning the mixture)...you could remove the ACT sensor and check it for oil sludge (a problem you were dealing with not too long ago....right?)...if it's too contaminated...a replacement is suggested. Do check how the system does in a KOER self-test though. My 2ยข.

90Mustangfan

check your ect sensor it could be telling the car that its 120* out and its taking out fuel check that, heres a good sight for looking up sensor and such helpful sight

Tims 88GT

what is the ect? coolant temp sensor? come to think of it, when i put my holley on the act was very dirty maybe i should replace it.

Joel5.0

Yep....Engine Coolant Temperature (=ECT)......and recommend replacing the ACT.