Brief spec;

MY97 T2000 with STI RA fully forged engine, VF22, full decat system, Forge VTA valve and Simtek.

Now recently the following mods have been carried out;

New billet fuel rails, parallel fuel setup, AFPR, Oil catch tank setup, Samco rally turbo pipe.

After all this was fitted the can ran really smooth and I had no problems at all. But recently the car developed a slight missfire when under heavy boost, but was fine on normal driving.

Took it to the garage to see what they thought and whilst it was there, the missfire got worse and was present all the time and ran lumpy at idle.

After changing spark plugs, fuel filter, coil pack, HT Leads and injectors the car was running smooth again. However, after I picked the car up, about 10 minutes of steady driving the car started to run lumpy, pops and bangs all the time and the car just wouldn't pull away. Managed to get it back home but trying to reverse onto my drive was a nightmare, as soon as I start to reverse the pops and bangs got worse and the engine just kept cutting out so had to push the thing onto the drive, wheres its sat for over a week now.

So now I have to get the car recovered back to the garage in the new year if I cannot sort this out.

Please please if Santa is on here, make my Christmas and help me get the Scoob back to how she was. Failing that, if anyone can help or advise on what to try next that would be much appreciated.

In the meantime, Merry Christmas (in advance).

 

It sounds like it's got a massive fuel starvation issue and running extremely lean, that causes backfiring. Your garage needs to be checking for fuel leaks around the new fuel rails and injectors.

If your fuel pressure regulator has not been set up properly if could be working at too high a pressure and causing the injectors to leak around the seals where they sit in the fuel rail. Perhaps they didn't fit them properly in the first place and pinched an 'O' ring. When under boost most FPR's work on a rising rate prinicple and fuel pressure rises to meet demand thereby working at an even higher pressure than for normal driving.

That's my guess

 

That`s what they initially thought, hence, replacing the the injectors and seals. This made the car run fine for an hour or so but then the problems came back.

Will take a look myself though and see if they are all seated ok.

 

Check and see what pressure your AFPR is set to if there is a gauge on it. If set too high they will leak no matter how good the seal.

 

Try unplugging the cam sensor when its running, does it run better ?

 

Is that the camshaft sensor? Where abouts is it ??

 

Top front of the passengers side head, by the oil filler cap.

 

Cheers, I'll try that tomorrow.

Injector seals all look in good condition. Will take some readings off the FPR as well.

 

What a nightmare. Went out to the car yesterday and couldn't get in using the alarm remote as the car battery was dead. All door locks have been removed and smoothed over by previous owner. So, I had to get my nephew to fit throught the centre armrest hole in the back seat to unlock one of the rear doors.

Battery fully charged and fitted this morning, I started the car and althought it was running like a bag of she ite, I managed to unplug the cam sensor. Engine just cut out when this sensor was removed.

Started it again, didn't touch anything and it cuts out within a few seconds everytime now. Started it again and looked at the FPR reading and it shot straight upto around 55PSI Now I was there when the garage set the pressure and it was set to 43PSI or whatever the standard pressure is.

Also, checked each lead from the coilpack and got a good spark from each one.

So apart from adjusting the fuel pressure and trying a new coilpack. I'm out of ideas and I think it will be best to let the experts take over.

 

55psi is 3.79bar. You're injectors shouldn't leak at that and as far as i know should take 4bar with no probs, although i could be wrong, so at that pressure your injectors are flowing a bit more fuel than normal.

Normal scooby fuel pressure is 2.8bar at idle to 2.2/2.3bar on demand so you're over .5/.6bar more pressure than where it should be but even then it shouldn't be running that badly and just a bit rich although how do you know the gauge on your FPR is accurate as it could be fuelling a lot more.

The only other thing i could suggest is go back to your original OEM FPR and see if you get the same issues. If so then it's something else.

 

To much hassle to put on the OEM regulator as I've got the parallel setup and braided hoses/-6N fittings everywhere.

Borrowed another coilpack, checked to make sure the car still started before doing the swap and now the bloody car will not start. Turns over but that's it, and the engine light now stays on.

Pointless clip but here's what happens;

YouTube - MY97 Subaru Impreza

 

My FPR needle doesn't swing over like that when cranking the engine. Not that i've noticed anyway although someone else may say different, but it's not the FPR is it that's the problem and you're just flooding the engine??

Same when on the move and you get all that misfiring and holding back. Are you over fuelling a lot?? You might want to check your spark plugs to see if they are soaked.

 

are you still running a maff as you have simtec. just an idea, seems to be popular one.

 

Running Simtek and yes the MAF has been removed.

I think it can only be down to over fueling now as the smell of petrol was very strong when it did start up a couple of days ago. I'm now starting to think that the garage have done something wrong when they fitted everything.

I'm going to speak to powerstation on Monday to see if they can sort the car out and get it all tuned and running smoothly again.

 

Yeah, will have one last try tomorrow but back to work on Monday so running out to spare time.

Thanks for all your advice so far, much appreciated

 

Ok, had the car recovered to the garage on Tuesday, great timing.....just before the snow hit us.

Phone call this morning to say that it's now running smooth again. Turned out to be the Lambda sensor was at fault.

 

With the Lambda gone it would have been overfuelling hence the strong smell of fuel. Good to hear it's fixed. Nice one!!

 

Yeap, just picked it up and drove it back to work, no issues so far

 

I'm back.....................

Took the car out to fill up with petrol today, about 15 minutes into my journey and the car started to jerk a little when accelerating. Filled up with petrol and pulled over before leaving to check the fuel pressure reading. With the vac pipe off the reading was around 56PSI, which is still too high. So the garage didn't check this before letting me drive it away

Drove back in a low gear, not going on boost at all. When I got home, I took pics of the FPR readings at idle with the vac pipe disconnected and then connected. Then a quick video;

Vac pipe connected;



Vac pipe disconnected;




Video clip;

http://www.youtube.com/watch?v=695NmeDucjo

(Yes, I pushed the vac pipe back on fully when I turned the camera off)

I will adjust the pressure back to where it should be tomorrow and see what happens. I know the car needs to go back onto the dyno for some fine tuning after everything that's been done recently so maybe that will put an end to this thread. Car starts up without any problems and currently no missfire or backfires have crept back in, so not all bad.........................

 

All the fine tuning should be done on the road not the dyno.

 

Adjusted the fuel pressure back to where it should be, but still no different. Jerks when accelerating and wont boost at all.

So I'm calling powerstation tomorrow and getting it booked it there as I've spent hundreds of pounds to sort the car out and everytime I take it away, the problem comes back.

 

It sounds progressive from start up which could imply it’s a map issue, temp/fuel related or temp sensor etc. I would be inclined to have this checked on the road measuring AFR as you go, before spending on parts you may not need.

Also worth checking the MAP sensor and pipes etc, as a map based ECU any changes in manifold pressure will affect fuelling allot more so.

 

This is the first time you've mentioned it won't boost and the word jerking rather than misfire. The jerking and no boost you describe would suggest either a MAP sensor or major boost leak issue. If you have a mate with an identical car borrow his MAP sensor just to eliminate that issue. I'm betting on a boost leak based on what you've just said.

Generally if the coolant temp sensor has gone most of your problems arise in startup and cold idle but when the engine has warmed up those problems usually go away until the next time you want to start from cold.

 

These problems are new

Missfire and backfire problems have now gone away and all was fine for about 20 minutes, then the above problems started.

Called Powerstation this morning and booked the car in for this Friday. I will take a look for any leaks though.

Cheers guys.

 

POWERSTATION

Just over 2 hours and the car was was running perfectly and much better than it's ever been.

2 Main problems were that the temp sensor wire had been routed along side the HT Leads causing the missfire(not by me), and the fuel pressure regulator was set wrong.

It's now running 326/413, from a VF22 with supporting mods.




Lets just say the drive home was awesome