shuttlegoose

iTrader: (17)

Im having some issues with my evo. At around 1800-2200 rpms my afrs will shoot to the 9.x-10.x area and the car bucks like crazy. My car is also throwing a cel which i feel could be a part of this issue. I was logging with evoscan and tried to see what the cel was and i believe it said something about a fuel pump relay. I did a quick search but only found info about evo Xs having this problem. I do have a 255 fuel pump and fic 850 injectors. Could this problem be related to my tune, or is it a fuel pump problem??

shuttlegoose

iTrader: (17)

Bump for any ideas??

todd6027

iTrader: (10)

get the exact cel code and go from there

darkside4G63

iTrader: (1)

+1 too any posiblities of the source of the problem

darkside4G63

iTrader: (1)

although if i had to guess it sounds like a serious boost leak

todd6027

iTrader: (10)

shuttlegoose

iTrader: (17)

i don't think its a boost leak. I just had all my boost leaks fixed including tbody shaft seals. The major leak was coming from the jpipe but that was fixed as well. Im leaning toward a bad o2 sensor.

Kracka

iTrader: (49)

It could be a tune issue. Pull that SES code and report back.

Kracka

iTrader: (49)

Mind posting or PM'ing your injector scaling and latency values? I have the 255HP and FIC 850cc combo too and might be able to help you out. Also, take a look at what your fuel trims are.

shuttlegoose

iTrader: (17)

my scaling is 770 off the top of my head but i forget my latencies ill have to check. I just logged my o2 sensor and it hit 0.0 a couple times. I think it may be on its way out or already dying because it just started happening with no change in my tune from when it didn't happen to when it started.

shuttlegoose

iTrader: (17)

codes are

p0172
p0134
p0138

MeFryRice

iTrader: (9)

Is this only happening on a cold start or even when the vehicle is warmed up? I noticed my car tends to buck if I just get in it and go opposed to letting it warm up first.

gsrboi80

iTrader: (38)

a major boost leak could cause the P0172. Got this once from huge leak at the j pipe on the old 20g set up.

The other two codes are front O2 codes could be time for an O2 replacement. This could def be a fueling issue though. However you tune is not just going to go bad if you were tuned previously and this just started happening I'd look elsewhere

evolution2186

iTrader: (5)

Could this be spark blow out you're experiencing? Check plug gap.

shuttlegoose

iTrader: (17)

thanks for the tips. The p0138 is the rear o2 i believe which makes sense because i just had a test pipe made and i think the j bung is welded at a funny angle and close to the heat shield underneath the car which could be throwing that.

The bucking happens any time. Cold start or warm start. It is very bad when going uphill in particular. I think it happens because its causing my load values to go up. When you look at a log of this stuttering happen the load shoots to 130-160 and afrs into the 9s. The hill may be putting that extra load into affect causing the stuttering condition. I looked at the fuel table at this load and rpm and the number in the cell of the table doesn't really correlate to the value thats being logged through the wideband.

A front o2 sensor may need to be replaced as well as more dialed in scaling and latencies. I just want to see if anyone has any other ideas.