GC8 Running rough!! Plz help!
 

Hi Guys

im new to the forums (still yet to introduce myself)

I bought a GC8 4 weeks ago, had high km, body was in good condition, 3" dump and exhaust, front and rear whiteline sway bars and a unichip

2 weeks ago it was hot in adelaide, and we washed the car while it was running, totally forgetting the previous owner put a pod filter on it, right below the drivers side bonnet vent.

Subsequently it sucked in a heap of water, however the water didnt stay long in the engine and it soon cleared out.

Since then, the car has had a rough idle and is down on power, im guessing a good 25-30% in power, but its still very driveable and still damn quick.

It has a misfire around the 4500rpm which we cant seem to get rid of, aswell as cant seem to find the missing power.

a week ago i washed the car again, put a plastic bag over the pod, removed the bag and started it up, and it was idling fine, and had all the power back right up untill i switched it off again.

So far i've replaced

Fuel pump
Fuel filter
plugs
leads
air flow meter
air filter (pod filter)

This morning i plugged the black and green connectors in under the dash and from what i could see it pulled up error codes 22, 23 and 53

Im yet to fix these codes but im looking at doing a compression test in the next few days as i believe it may well be a more serious problem then just a sensor.

I've done some reading and everything i've looked at seems to refer back to cyl #4 and burnt valves.

Has anybody encountered a similar problem in terms of roughness, misfire and lacking some power? it almost sounds as if its running on 3cyls but its definately not.

If it is a burnt valve, how much is it going to cost to get the heads rebuilt?

Its my first subi, i dont know much about them :|

any help would be appreciated


adz

How much boost are you running?

[QUOTE=Rossco;782531]How much boost are you running?[/QUOTE]


i have no idea tbh mate, dont have a boost guage in it.

im guessing 10-12psi but wont know till i can get a boost guage in

Burnt valves means it's been running VERY lean - don't thrash it until you have it diagnosed properly.

FYI error codes:
22 Knock sensor
23 Mass air flow sensor
53 Fuel Pump or Circuit

I'd say you MAF died - you boosted it and it knocked itself to death. Swapping the MAF won't fix it because the damage was done the first time you hit boost when it was running sick.

[QUOTE=Rossco;782542]Burnt valves means it's been running VERY lean - don't thrash it until you have it diagnosed properly.

FYI error codes:
22 Knock sensor
23 Mass air flow sensor
53 Fuel Pump or Circuit

I'd say you MAF died - you boosted it and it knocked itself to death. Swapping the MAF won't fix it because the damage was done the first time you hit boost when it was running sick.[/QUOTE]

i dont give it much if anything tbh.
gave it a few squirts when i first bought it.

not sure what you mean by the last part, but im assuming your trying to say the engine is pretty much dead ?

i guess a compression test will show abit more then what we already know?

[QUOTE=adammm;782548]i dont give it much if anything tbh.
gave it a few squirts when i first bought it.
[/QUOTE]


But you've only had it for 4 weeks, how about the previous 13+ years?

[QUOTE=matto20v;782551]But you've only had it for 4 weeks, how about the previous 13+ years?[/QUOTE]

thats the question, however
the previous owner had it for some time, done 120,000km on it, was a female owner with 2 kids, sold it on to me as she had a 3rd kid and well, we all know how big the back of a rex is.

means absolutely nothing tho as she could of been a lead foot.

on another note, i reset the ecu an hour n half ago, the idle is no longer rough like it was, no ecu codes are showing up after driving for awhile and rechecking, however its still down on power and has a misfire at the exact same rpm as it use to which is around the 4600rpm mark on full throttle.

light throttle it doesnt misfire and continues on through the rev range, full throttle still continues on past the 4600rpm mark but its hesitant and has a misfire

:|

Check your plugs

[QUOTE=GX-REX;782557]Check your plugs[/QUOTE]


plugs were the first thing i changed when it started doing it
have also replaced leads, fuel pump, fuel filter and air flow meter so far

Clean the MAF.