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240smoke
12-20-2009, 11:07 PM
I have been dealing with this issue for some time now and its driving me crazy, I cant figure it out.

The computer isnt throwing any codes, I have spark in all coils, injectors tested good, TPS tested good, MAF tested ok. Compression is good. And I tore my engine harness apart and put it back together. I was having this issue before I ripped my harness out.

When I start my car, my AFR starts out at 14.8 then slowly goes to full rich. Then I start to give it throttle under load and it leans out fully. And if I give it a little more throttle, it goes rich again then back to lean with full throttle.

I am able to pull my MAF plug off and rev it to redline which I dont believe I should be able to. I think its supposed to go into a safety mode where it limits the revs to 2500RPMs. I know my MAF wiring is ok because I just had my harness apart and did point to point testing on the whole thing.

when the engine has reached normal operating temperatures, it still runs like ****. But if I turn the ignition key to off then restart it, the car will run perfect sometimes. I am completely dumbfounded to this problem. Would an O2 sensor cause this?

Is my computer bad? Any suggestions would be great.
Sterlz
12-20-2009, 11:24 PM
A faulty o2 sensor would probably have it running rich at all times. Iirc an AFR at 11.3 or 8 or w/e is just fine on a turbo application. 14.8 might be a bit towards the lean side?

Are you sure it's not the mafs?
240smoke
12-20-2009, 11:38 PM
I am able to unplug the maf and rev it to redline. If I unplug the maf, i can drive it around and it runs exactly the same as when the MAF is plugged in. I checked the wiring though when I pulled the engine harness out. it was good.
240smoke
12-20-2009, 11:40 PM
idling, the AFR is 10, then when I start to accelerate, it quickly goes to full lean and goes off the scale. Then if I give it more gas, it starts to go rich again and then when I give it half-full throttle it goes to full lean once again. Its around 10.5 at cruising speeds. And when I am decelerating, its at 14 AFR
Sterlz
12-20-2009, 11:51 PM
Very very strange. Not a standalone right?
240smoke
12-20-2009, 11:57 PM
no, I have stock 62 ECU. I do have a stand alone still sitting in the box but I wanted to get the motor running correctly before I install it.
Sterlz
12-21-2009, 12:24 AM
Shit dude. I'm stumped, hopefully it's just that o2
240smoke
12-21-2009, 12:46 AM
but would an O2 sensor cause it to lean out? Is the motor really that dependant on the O2?
240smoke
12-21-2009, 02:03 AM
anyone else have any ideas? I have gone through alot of troubleshooting and still havent come to a conclusion.
Sterlz
12-21-2009, 12:13 PM
Injectors? FPR?
rc1honda
12-21-2009, 02:14 PM
Pull any codes from the ECU. Try a different MAF switch it out for a known working one. Check fuel pressure and spark plugs for correct gap and heat range. Check for vac leaks.
240smoke
12-21-2009, 02:30 PM
I havent checked FPR. I did feel pulsing in the fuel when I sqeezed the line. I dont have a fuel pressure gauge.
clark
12-21-2009, 02:42 PM
maybe swap in a new coolant temperature sensor (CTS). i'm not the type to randomly replace sensors, but these are cheap.
240smoke
12-21-2009, 02:44 PM
alright, will do. thanks man.
240smoke
12-22-2009, 02:53 AM
alright well I installed my AEM EMS into my car today. The car fired up and is running. Getting a reading from all the sensors so I know they are all good. She seems to out of timing though for some reason. Maybe the preloaded map was just a base tune and she needs properly tuned. she is running really rough at idle. I dont think I can even drive the car in this condition.
S117A47
12-22-2009, 08:28 PM
Pull any codes from the ECU. Try a different MAF switch it out for a known working one. Check fuel pressure and spark plugs for correct gap and heat range. Check for vac leaks.
x2 on maf.
steve shadows
12-24-2009, 04:26 AM
alright well I installed my AEM EMS into my car today. The car fired up and is running. Getting a reading from all the sensors so I know they are all good. She seems to out of timing though for some reason. Maybe the preloaded map was just a base tune and she needs properly tuned. she is running really rough at idle. I dont think I can even drive the car in this condition.

let me know if you want a base map from me, it might help get you going in the right direction.

I can do yours for a discounted rate. pm if you're interested