Trashman

Hi All,

Ages since I've posted and hey what do you know I'm posting now coz I have a problem

OK, last night coming home, car running fine, booted it off a roundabout as it was busy flew forward changed to 2nd, had what I presume was my second fuel cut (in two years ). Quickly followed by full power and off down the road again.

Put it down to fuel surge (though I have only ONCE had this in all the time I have had the car) and thought no more, though glanced in mirror and saw ORANGE smoke??? WTF? Anyway car felt OK the rest of the short way home and all that was slow so didn't notice any other problems.

Coming home tonight, I dunno, car just didn't feel right. Actually it hasn't for a while but I thought it was just the rising temps. Then pulling out from a junction and accelerating hard, same fuel cut. Hadn't filled up (still over 1/4 tank) since last night so thought maybe it is fuel surge again.

Only then did I start really paying attention to the car. It is really down on power off boost, takes ages to build boost and doesn't boost as high (it used to peak at a tad over 1.4 on the Defi guage then hold at 1.1 in 6th, now peaks at 1.3 - struggles to get there - and holds about 1.0).

Almost felt like crap fuel so filled fresh with Optimax and a dash of NF Race as per usual - no improvement.

Had a nose under the bonnet but no obvious noises, leaks or rattles, only other thing I can notice is a few pops in the exhaust if revving it high then closing the throttle. Engine seems to take a while dropping back to idle - also noticed this in traffic - in 1st at say 1500-2000 revs you can take your foot of the throttle and it gently slows down (almost as if there was no compression ). Have also noticed inside of exhaust is orangey/tan colour whereas I'm sure it is normally (a little) sooty? So presumably running weak?

So, down on power, slow building boost, boost slightly down at max, engine revs don't drop quickly to idle and exhaust not normal colour. Any clues? I'm going to try and get it booked in this week but pointers would be helpful! I'm guessing O2 sensor or possibly MAF?

Car is a standard MY02 Sti Prodrive (not PPP) Type UK with 68K miles. Only mod to drivetrain is a Scoobysport exhaust.

TIA

Trashman

Blimey! Page 2 already! No ideas anyone?

robsw

Could be your MAF sensor, do a search on here you will find the odd test you can do. Or you cound try doing the ecu self-diagnosis, to see if you get any error codes.

Robin.

RRH

I wouldn't panic too much about residue in the exhaust- it's more than likely from the octane booster.

Did the car show any check engine lights? might be worth getting it monitored on delta dash or a select monitor. It will typically make less boost in warm dry weather than cold and damp, although I'm sure you know that already.

Hope this helps,
Simon.

Trashman

No CEL, apart from feeling "off" or flat, and the boost being slightly low (and slow to build), there is no other indication of a fault. I'm sure the exhaust is usually slightly sooty.

Started this morning and seems "ok" off boost, but on boost same as before slow to build and doesn't peak quite as high as usual. Yep, warm & dry I'd expect a drop, but today was cool first thing and although it felt better than last night (which I would expect) still not right. Boost has always hit peak of 1.4 on the gauge even in the height of summer.

Only thing I did notice this morning is the exhaust sounded loud - possibly it is an exhaust leak as this might explain "off" rather than dire performance (and possibly the pops on revving). Let's hope I don't have to go and buy a new downpipe or system ( ) now that would be really bad as I would then just have to have a remap to go with it ( ).

Could an exhaust leak cause the effects I'm having?

Trashman

Dealer fitted me in at short notice this morning.

They checked the wastegate actuator, boost solenoid, checked for any faults in the ECU and reset it anyway, couldn't find any obvious leaks in exhaust or intake side.

They agree it isn't right, but said the next step would be to pressure test the turbo/inlet etc and would need it in for a couple of days.

They said to try it after they had reset the ECU - just had a blast (not) coming back and it is still the same.

Put as concisely as possible, boost comes in late and doesn't hit peak. Think other symptoms may have been spurious/red herrings.

Dealer can fit me in next week but I can't get time off and of course no guarantee they are going to be able to diagnose then either. Really need something else to go on.

Help.

Trashman

Anyone?

vulnax999

iTrader: (7)

Are there no Scooby specialists near you ... ware the Dealers!!!

Check there are no splits in hoses after MAF or turbo, but this sounds like a blown gasket in exhaust headers / up-pipe to turbo ( so less exhaust gas to spin the turbo so slower response/build of boost and lower top boost ) which would also make the exhaust noisier!

Other rich fuelling problems could be Lambda sensor, possibly but not likely from your explanation the MAF - these would show CELS IIRC, or possibly a failing injector or spark plug / coil pack ( if your model has these individual packs ? ) .

Trashman

Cheers...was originally suspecting an exhaust leak but they said today no obvious leaks on intake or exhaust - maybe I just imagined it; plus they say plugs etc all OK.

Problem is I don't think anything is going to show just ip on a ramp - bear in mind one of the symptoms is boost not reaching peak (about 10% down) in 6th on WOT at 4K+ which wont show by revving the engine off load.

I'm guessing, unless it is a known fault, that I'm looking at a rolling road session but before I commit to any expense and time off the road I need a good idea of what it could be.

TBH the dealer I go to is one of the few good ones. Only ever had positive experiences and they have enthusiasts working there too - even the fact that the main guy on reception always remembers my name is a small touch which you don't see often (in a different industry, I am a Customer Service Manager and believe me they do give excellent service/customer care).

Anyway, any other offers on possible solutions or any specialists in south/south east reckon they can sort it for me?

CRX-Ownage

Been on the rollers today with a manifold leak and broken lambda sensor. I've got a full de-cat from the manifold back and i've had similer issues!

Before the mods the car had alot more go.. check your lambda sensor, and idle valve?. what about fuel filter?

Trashman

Lambda checked out OK, apparently.They haven't checked fuel pressure as yet as far as I know.

scoobyboy

did they check the readings for the air/fuel ratio sensor (not an 02 sensor) and is the neutral switch working ok?

Trashman

Apparently "all" sensors checked OK, what would be the symptoms if AFR or neutral switch were faulty?

vulnax999

iTrader: (7)

Sorry, I am not familiar with those, wait on Scoobybiy!

scoobyboy

the air/fuel ratio can mess around with the fueling giving the loss of power feeling and the neutral switch can affect the cam timing if you got the vvt all checkable on the select moniter.

Trashman

I'm purely guessing AFR is OK, by the fact that when it is boosting, it is "ok" and it seems OK off boost. Just that the boost comes in late and doesn't quite hit max.

Been reading up on Neutral switch since your previous post. If it stuck in the neutral position, do you get any other probs? Just wondering as I did have an intermittant problem where boost would not go above about .6 which would suddenly clear and then be fine. After a service, when I mentioned it, they cleaned the boost solenoid out and it seemed to be OK. Also found a hose of of the breather pipework which may have caused that problem.

But all that was some time ago (prob 12 months and 15K miles at least)...except a few weeks back it did the .6 bar boost again. Sounds like an interesting one to follow up if and when I can get back to the dealer. Though I'm assuming it would show up on the diagnostics?

Have read that moving in out of gear while idling should show a 'blip' on the revs - any other simple checks (bear in mind I have no where to inspect the car and no real tools etc.)?