lean issue d15b7

[j0keefe21]

ok so i just put back in my basically stock d15 for a little and it ran fine at first. i had tuned it a little on crome and then one day when i step on it and only when i hit100% throttle my wideband will go all the way lean. thinking it was my tune i adjusted the tables and still no luck, so i swapped out the chipped computer for a completely stock ecu. still does same thing. runs fine around town but when i step on it it goes super lean but on decel it does cut the injectors which makes me think the map is working... any help would be great thanks and btw when i say lean i mean my gauges maxes out at 20 to 1 and with my aftermarket regulator i need 80psi for it to idle

 

[RonJ]

Sounds like a fuel pressure regulator problem.

Any CEL codes?

 

[j0keefe21]

no codes. and i thought the same thing, thats why i put the after market one on. both stock and after market are doing the same thing. oh and also i back probed my harness at the ecu and got good readings from the ect and at idle my map was fine but i didnt drive it. has a walboro 255 in it and is about a year old

 

[RonJ]

What voltage was the MAP sensor outputting to the ECU with the engine idling?

What voltage does the MAP sensor output to the ECU with the engine off and the key in ON(II)?

Is the fuel filter possibly clogged?

Have you measured the fuel pressure with and without the vacuum hose for the FPR connected?

 

[j0keefe21]

.9v at idle and 2.9 v KOEO.. fuel filter is fairly new and the regular raises progressively with boost. i might just do a new fuel filter for shits and giggles cant hurt and ive heard they sometimes collapse inside

 

[j0keefe21]

ok well i tried a new filter and that didnt work, i pulled the pump and it flowed a gallon in about 50 sec. i checked my lines and nothing seems to be crushed. i just dk where my problem is

 

[RonJ]

When the fuel goes lean, do you notice any performance problems? Is it possible that the O2 sensor is bad and misreading the air:fuel ratio?

 

[j0keefe21]

no it seems to run pretty fine and i would say it might be the 02 sensor but it only runs lean in open loop. i dont see how my WB02 would only mess up when the car is in open loop. today i changed out the map with another i had sitting around and still no change, about to put some other injectors in it just to see if it will do anything.

 

[RonJ]

no it seems to run pretty fine and i would say it might be the 02 sensor but it only runs lean in open loop. i dont see how my WB02 would only mess up when the car is in open loop.

The question is whether you really have a lean open loop condition or whether the O2 sensor is deceiving you into believing that you do. If the fuel mix were really lean at WOT, then you should notice a significant performance problem. O2 sensors are complex, so I don't think you can always predict how a problem should manifest.

 

[j0keefe21]

well i took your advice and looked up how to test a wideband. i found a good video that aem did on youtube and tested it the way they said to. just like their bad 02 mine read full rich when placed in a rag soaked with brake cleaner and then quickly went back to full lean. so in all it was my wideband and nothing wrong with my fuel system. i couldnt find the problem bc there wanst one there. but hey atleast now i have taken a close look into my sensors and fuel system and know it is all working well. lol and thanks ronj your the only one i could get logical answers from on any forum.

 

[RonJ]

Nice job figuring out the problem. Could you please post the link to the video. Who knows, someone else might also benefit from knowing how to test a wideband O2 sensor.

 

[j0keefe21]

heres the video on how to test a wideband http://www.youtube.com/watch?v=1mb4VmDd0ao