alice6

I'm having a hard time tracking down whats causing my car to misfire under load. My wideband sensor recently went bad so I can't tell for sure if its going rich or lean when its misfiring. it idles fine and drives fine under light throttle, but whenever i go into boost it sputters and feels really sluggish, and the check engine light blinks (cylinder 2 misfire i believe). the codes read: multiple cylinder misfire, cylinder 1 misfire, cylinder 2 misfire, cylinder 3 misfire, and cylinder 4 misfire. I have replaced the spark plugs, spark plug wires, ignition coil, and fuel filter. i checked the fuel pressure at idle and its right where it should be. injectors are fairly new as well, only a few thousand miles on them. what else could i check?



edit: forgot to mention it is turbocharged, with the maf and idle valve hooked up pre-turbo, and BOV is recirculated.

Bommello

I'm pretty sure with the car sputtering and being sluggish you are rich. You can also look at your plugs to see if rich or lean.

alice6

little update: i got a new wideband sensor in and took it for a drive increasing the load slowly. looks like its shooting lean under higher load :S yikes! i'm still running the stock fuel pump and regulator, with the fuel pressure good at idle could either of these be a problem while under load?

Turboron_99

Get a bigger fuel pump, if your going lean, up top you need a bigger pump, but you will need some kind of FPR to control fuel pressure, i would tell you to get a Rising Rate Fuel Pressure Refulator, like atleast 1-1. That way you can set your idle pressure at 40 and for every lb of boost your psi will go up 1psi of fuel pressure keeping you running with FUEL!



Yet, you need a bigger fuel pump and FPR.



Also what are you using to tune, if your running the FIC, you are running the 104x file i bet, you need to flash the x110 file, and you will be running sweet!

steelcoffinx3

A misfire would read lean, try gapping the plugs down.

alice6

i'm using an FIC to tune, i'm not sure which file i'm using though. i know i need a bigger pump and regulator but i'm in college so money is a bit tight. i don't think thats the whole problem though since it's not just running lean at the top, its going lean as soon as i go open loop. i'm going to check my fuel trims and see where they're at, i ran this tune for a month for testing and my long term trims were at +0.8.



i'm not sure if ignition would cause that. As i see it, if the mixture fails to ignite due to spark, it would then go through the exhaust unburnt and be read as rich. however, i'm no expert.

Turboron_99

?when you plug in your laptop to the fix, just do a reflash it is easy and takes just a few minutes, the only thing you will need, is a tooth pick or something slender and long to push the reset button on the fic, you laptop has all the files you need, they will pop un with the option.



When you open AEM FIC program, then you click on FILE, Then Click on FLASH FIC... It will walk you through step by step, you need to be running the 110 hex file, that is the only file that reads our injection signal in open loop, closed loop runs fine! I am almost garunted that this will fix your issues. I had the same issues for a bit, reflashed then BAM fixed!



Do the flash and it should fix your fuel issues, then check trims!

steelcoffinx3

The o2 sensor would read all the unburnt fuel and oxygen, more oxygen=lean reading.

alice6

i think steelcoffinx3 was correct, i replaced the fuel pressure regulator with a spare i had laying around and reset the computer and took her for a drive, she's working again! but i've been keeping an eye on the afr gauge and its slowly getting richer, so i need to adjust the O2 map. my base afr was set to 12.0:1 under boost, after about 300 miles its now at 11.0:1. thanks for the help guys



oh and btw, for anyone that has an AEM analog uego (i think the same goes for the digital but i have an analog) if you need a new sensor you can use one from an 02 impreza 2.5 non turbo.