THESLEEPER

I need help
Problem- car idles fine but bogs down throughout the rpm range then at 4k rpm it really bogs then at 5k rpm I get pre detonation engine knock
What I have 2002 wrx. With utec
What I've checked or replaced

Replaced all four ignition coil packs
Replace spark plugs
Fuel filter and gas
Cleaned maf sensor with maf cleaner
Checked o2 sensor-good
Compression is 165 psi in all 4 cylinders
Tried running without utec install- don't help
Checked fuel pressure- 90 psi

Help please!

zer0shift

90 psi at idle that high even at WOT

RallyGC

iTrader: (3)

He has a point there. You don't have a Tactrix cable do you? I would run some logs see whats going on first. Are you running stock? Stg 2? Something else?

THESLEEPER

We didn't have proper equip to test fuel pressure so we just disconnected the outlet of the fuel filter and put a gauge directly on the end then turned the ignition on and the thing show 90 psi .

Car was running fine then just went to crap. I'm running stage 2. I reloaded the map and it didn't help. Ran it with the stock ecu... Didn't help. I didn't change anything to cause this. Turbo is boosting fine also.

THESLEEPER

Car is also not throwing a check engine light. Hooked up a obd2 diagnostic and got nothiNg.

dub81

iTrader: (39)

Never mind....LOL... IF its truly pre-d, it could be a variety of things or a single thing. Un-Normal combustion is occuring.


ninja

THESLEEPER

Just got a check engine light, misfire in cylinder 1 and 4

spinplay01

iTrader: (12)

See if your timing belt has jumped a couple of teeth. The would usually throw a code...but sometimes doesnt.

When did this problem start? Had you just worked on something?

And as with any problem that may be electrical. Double check your grounds. (check resistance, not just visual check)

Check ECU ground and power inputs voltage.

Idle air control valve maybe.

Cam or crank position sensor maybe. Has your tach acted up lately?

Try to borrow someones MAF for a minute.


This is all I can think of at the moment.
If none of this leads to rectification (haha) let me know.

THESLEEPER

I was thinking timing belt could have jumped a tooth, went to check last night and i could only get 2 of the cam cover bolts out

i didnt do anything recently to the car, tach hasnt acted up at all.

Would the maf sensor in an 06 imprezza outback sport be he same?

spinplay01

iTrader: (12)

I'm not sure about the compatibility of the MAF sensors. If you have access to one, give it a shot. But dont count it as solid troubleshooting unless you confirm that they are the same (or superceeding) part number.

THESLEEPER

Ive heard the idle air control valve can cause some problems, how do i check it?

joejoe69

iTrader: (2)

Just pull it out and clean it up. If it idles fine, it doesn't affect driveablility, only in idle and first startup.

So when you go up to 4K does it feel like you've hit a wall, along with loud popping noise from your exhaust? If so, that's a misfire. If you hear grinding noises while accelerating, that's pre-ignition or knocking. Do you have an adjustable FPR?

THESLEEPER

No popping from exhaust, and that code only came up that one time just freeway cruising .

Like you said it feels like i hit a wall @ 4k rpm , the car feels like something bad is gonna happen then pre detonation. With hmy laptop hooked up to the utec it says engine knock event.

Dam im loosing sleep over this.

houdni

iTrader: (1)

dont know if this happens on subies...

but when we suspect the maf...sometimes we disconnect it and run the engine...pcm/ecm goes into default/limp mode and engine runs better...a quick dg to a bad functional maf...

my first suspect is the maf...major and vital input.....I've had my project stangs mafs go bad...put it all together...rev it up to 4K and just hit a wall..wouldnt rev up...and bogs...was the maf....... maf can also cause the engine knock...cutting off fuel...

if you can monitor pids to the maf and rpm...it would help..should be an identical graph

joejoe69

iTrader: (2)

The MAF could be pegged at, say 3.5-4.0V instead of 5V at WOT. Same principle, so if your voltage is cut short, so is your fuel.