Hi all
past month and half scoob been playing up.
AFR Gauge shows 'rich' as far as it will go when playing up and chugs like mad on acceleration (floor it and it smooths out abit). So im guessing it is over-fuelling?
But why? i have new lambda, plugs, coil packs, walbro pump.
Could it be a dodgy fuel injector or something?
It mainly happens when cold but can still do it when warm, if i go for a 10 min blast and warm her up then all is fine, just slight little hold backs through the revs.
It has just done it after a week of being fine then it rears its ugly head again.

I use optimax and have scooby ecu 15.5 psi, hks induction, HKS 3inch d/pipe and scoobyworld centre & vortex angled b.box. 93 wrx import

The chugging is really getting to me and dont know what it is, please help!!


Thanks in advance.

Tim

 

What did you Gap the plugs to ?? & the walbro could be providing to much fuel/pressure , Did you add/ change something then these symptons started ???

Dean

 

Well yeh, the lambda but the place i got it reckon its the correct one for the car, i on the other hand am thinking its not.

On my way home it even backfires and chugs on free revving to.

Im getting so peed with this car even though i love it to bits, im thinking of getting shut if problems dont stop coming up. I wouldn't ming but all i do is look after her!

Any other ideas?

Tim

 

The symptons you are describing do sound very lambda orientated, But then could be something else, you could unplug the lambda & then run it to see if it runs better, but don't thrash it.

Dean

 

ok i will give anything a try! have to wait till weekend though so any other ideas i could try after that if thats unsuccessful? Oh will i need to reset the ecu or anything?

Tim

 

Yes i would reset the Ecu, before & after could also be maf related, Do you have a friend you could swap parts with for teting purposes ?? would make life easier for you .
Dean

 

no not got anyone with car like mine, only thing i can do if cant cure it myself is to spend a fortune at pro-sport or jap innovations to try this, try that and charge loads for finding out whats wrong!, and money is not growing on tree's at the moment!

Thanks again dean

Tim

 

Sounds more like an ignition problem.
Lambda tends to under-read when duff, so if your AFR gauge is showing rich (assuming it's tapped off the lambda for the ECU) then it would seem to be working fine.

The only problem you are likely to get with a duff lambda is slight over-fuelling at part throttle when the ECU is trying to make the engine economical.

As mentioned above, check the spark plugs / gaps and fuel pump pressure regulator.

 

I'd agree 100% with Dave's comments above.

Given that it's only when cold I'd be looking more towards ignition problems.

Check also for air leaks, for example a sticky dump valve.

 

ok cheers everyone i will check plug gaps and for air leaks
Thing is though could the plugs b at fault when it only doea it say 80 % of the time and sometimes (if im lucky) it will be ok.
Does sound like an ignition problem, perhaps dodgy coil pack?

How do i know if its a sticky dump valve?

Tim

 

Quick advice please!!!

Just checked out ecu codes and its saying number 45 - pressure snsore AND number 23 - Mass air flow sensor.

Pressure sensor i replaced 2/3 weeks ago hoping that was it but its now saying that and MAF.

Time for a new maf??? would this cause all the back firing on acceleration at any speed?

Tim