iuchabar

Hi all,
I'm new to all this, just signed up to Scoobynet so hi to everyone! I have a specific issue with my WRX ppp 07? it has started to 'judder' when accelerating gently between 1500 and 2500 revs (in any gear) as if it doesn't want to pull, then suddenly it gets going - a kind of "stall, stall, stall, GO" I have had it plugged into diagnostics but no error code, it's been serviced and no difference... Anyone got any ideas or similar experience? Hope someone can help!

Chris T (iuchabar)

urban

iTrader: (1)

What fuel do you run it on?

Had the ECU been reset?

iuchabar

Hi - it's running on Shell V-Power only - since i bought it last August anyway! ECU is the Prodrive Performance Pack upgrade (i know it's pucka 'cause i got all the receipts!)?

Any ideas?

ta.

alcazar

iTrader: (2)

Plugs? A Boost leak? Coilpack?

iuchabar

hmmm. my guess was some sort of ignition issue - would a boost leak act like that or be more across the whole rev range? at high revs it still pulls like a train.... wouldn't coil packs show as a fault on the diagnostics though?

ta.

urban

iTrader: (1)

Always does it in any gear
When hot or cold?

How many miles on it?
Did you buy from a dealer?
I presume its still got some warranty left?

urban

iTrader: (1)

The older cars did have a bit of a flat spot around 2K
I've only driven STI's since 2002 so I can't comment any more

iuchabar

phew! questions questions!!!! only kidding, thanks for your replies..... to answer in order;

yes, hot or cold.
22000 (just had 20000 service but no plugs)
from a 3rd party dealer
warranty until June 2010

scooby1929

iTrader: (1)

Might well be the plugs if they have 22,000 miles on them. Prob past their best now

iuchabar

cool - everyone seems to be pointing at plugs / ignition system somewhere (which backs up what i was suspecting). Cheers all, I'm off to get some iridium plugs then - any recommendations? Easy to fit?

ta

spb123

thanks

M@RKB

iTrader: (1)

This is interesting, i've got an 07 WRX PPP (from new) and have had exactly the same problem. Three differant dealers failed to identify the cause and usually put it down to bad fuel, as no faults were stored. The car has now been modded with VF 43 turbo, STI TMIC, De-cat, walbro and the obligatory re-map and hasn't missed a beat since. So who knows ?

iuchabar

Update on this.... I took it to Cutlers Subaru Aldridge last week, they took one look, pointed at the MAF, ordered one, replaced it within 2 days UNDER WARRANTY and now the problem is... well MOSTLY gone. Straight after they replaced it, it was perfect. The morning after, the hesitation was back a little, but not as bad. Now, it is ok (ish). This is one of those probelms that i think will be with the car until i remap (like M@RKB). I am fairly sure it must be a mapping issue, but could be fuel (funnily enough i filled up at the weekend and this seemed to fix it mostly too).
SPB123 i may well write to Prodrive and see if they answer me the same! Although since Prodrive & Subaru have fallen out with each other i may not get a positive response! Other possible issues that may cause this could be knock sensor (after a service they can be twitchy ESPECIALLY if the engine hasn't been dry-cranked after oil change) or even the Lambda sensor? I may get back on to Cutlers Subaru and see if i can push them to replace those but i don't want to push my luck! If there are any more updates I'll poast them on here!
Still confused.... Chris.

iuchabar

SPB123 - do you notice it more when the car is almost empty of fuel? I reckon mine gets worse as it heads towards empty..... could this be a fuel pump issue? Maybe M@RKB saw an improvement partly becasue he now runs a walbro? I'm still confused...

M@RKB

iTrader: (1)

Hi chris, I also had MAF sensor replaced which possibly helped slightly but being an intermittent fault its hard to say. I had the fuel delivery checked but was told the pump was operating within it's peramaters.

weatherman

I've got the same problem on my Hawkeye PPP. Dealer couldn't find anything wrong at last service, and it seemed to be a bit better over the winter (cold intake?) but now with the milder weather it's back with a vengeance.

I too had the hesitation/jerk under constant throttle pressure at low revs esp when just started from cold, then on long journeys the car would seem to be fine at full bore 2500rpm runs (5.5s 20mph increments in top) but then it would flip to low performance mode (11.5s for the same increment and feeling like a n/a car).

Just now, it seems to be in permanent low performance mode, yet strangely the hesitation is not there. I wonder if that is because it is a permanent hesitation, whereas previously it was flipping quickly between low and high performance mode.

One thing I have noticed (and also mentioned to the dealer) was some sort of slight rasping at low rev medium acceleration like as though there was some sort of slight air leak, but once the turbo kicks in it is hard to hear it again.

The performance does seem to be better at higher revs though not to the levels I would expect.

iuchabar

Weatherman - all that sounds very familiar. My car is basically only boosting to 0.4bar now max. Guessing that is 'low performance mode'. The juddering / hesitation seems worse when it's raining, strangely, but is still there all the time. It is going back into Cutlers Subaru tomorrow so we'll see what they think. I am starting to wonder if this is actually a Prodrive issue.... Anyone out there got similar on standard / other ECU maps? Laterz.

MICAWRX

Howdee,
I developed a flat spot on my my05 sti ppp from a dodgy batch of vpower at woodall services.
I posted the issue on here and Mike Wood from Prodrive responded.
The map had 'learned' a retardation to cope with fuel and didn't correct itself.
An ECU reset was advised. One hour labour at dealer was ridiculous so bought and elm323 interface from Gendan and did it myself.
I am sure the dealer would have done this... Wouldn't they?

iuchabar

Update - Cutlers Subaru spent ages testing / roadtesting with the laptop plugged in for me yesterday. Funnily enough, with the diagnostic plugged in it suddenly boosted back to 1bar (but the judder was still there) - but it showed no errors. They are a bit stumped, but basically they will go over it bit by bit, starting with replacing the fuel-pump, then move on to solenoid valve, Lambda, etc... etc.... until (as i suspect) it will have a remap Ecutek Prodrive ECU.... we'll see! I'll keep this updated, as clearly this could be an issue with a few PPP Hawkeye's out there?... Laterz.

weatherman

Yeh keep in touch! My car is now just out of warranty, which is annoying, though I did report the problem while it was in warranty. I'm convinced it is the same problem I have.

M9JOC

iTrader: (1)

Wouldnt have anything to do with re circ or dump valve?? I had a similer prob with a TT a number of years ago and it was a spit pipe to recirc, £5 later car was sorted

tjmatt

iTrader: (1)

Could it be a suspect lambda sensor? Normally when they go bad they get slow and read lean - making car run richer and it doesn't affect things too much - but it it does the opposite and makes it a bit lean it could misfire a bit. Replacing the MAF makes it re-learn the fuel trims from O2 sensor vs the MAF reading and if it got worse again, chances are the O2 sensor reading rich and made it run lean again. It maybe that the default map (target afr) for them isn't great. Never had a newage so not familiar with them - but reasonably familiar with ecus and closed loop control systems.

The other thing is that if you have exhaust shield rattles and any noise that might get picked up by the knock sensor when it pulls timing you will notice it stumble.

dynamix

iTrader: (3)

Sounds like either overboost during the spool up period or the ecu is detecting det of some shape and retarding ignition massively to protect it. The ecu in the 06/07 cars can get a bit of a panic on if it hears something (sometimes it is false det).

They tend to do this if any modifications to the car such as exhaust changes or induction changes.

Easily cured in a remap.

weatherman

I think in my case it could be related to the slight rasping noise, either directly in that it is some sort of leak, or indirectly in that the sound of it is picked up as det and the ignition is retarded. Against that, is the fact that it did seem to be temperature dependent to a degree, in that it seemed to reach full boost in cold weather, and in medium cold weather up to 100 miles into a journey, before going to low performance mode. So either the retardation is only kicking in with specific intake temperatures, or thermal expansion causes the leak to be more significant at higher temperatures.
I favour the retardation option, as there seems to be fast mode and slow mode, no in between mode. I.e. that 20mph top gear interval either takes 5.5s or 11.5s, never 8s. Hopefully AWD will sort it out.

Then again I did have the juddery thing on starting from cold.
Anyone know what the position is with faults reported in warranty persisting beyond warranty?

Edit - just wonder if the rasping might be exhaust manifold leak causing intake charge to be too warm......

iuchabar

Update (again!) - had a new fuel pump fitted by Cutlers Subaru of Streetly... they were sure this was the problem - and it has worked... a bit. I say a bit, as this was the result after the MAF was changed too... a couple of good days after it, then back to the old problem. So we shall see. I AM beginning to suspect it is either the ECU map OR the knock sensor... but today (day after the fuel pump) and it is hesitating a bit from cold at pull away, although it is better through the range. Maybe someone at the West Mids Scooby club meet tomorrow will be able to help me! Laterz, Chris.

iuchabar

oh i forgot to say - Cutlers also told me to beware the boost gauge readings (i told them it was boosting to 0.4bar only) as they can be inaccurate....!!!!!!!!!!!!!!!

After i stopped laughing at him (i have prosports fitted by Scoobyworld - i think they are accurate to within 0.6bar... lol) i told him i would be back if it wasn't cured by the fuel pump!

laterz.

ZEN Performance

This could be the PPP ecu doing this on purpose. It's quite easy to make a sensible amount of boost on the wrx at low rpm, and for the ECU to keep the fuelling in closed loop to run it lean for the cat and MPG. With more throttle it will come out of open loop instantly, but with part throttle in the 20-30% range whilst accelerating a little, it works on a timer and will eventually go into open loop. Some cars make more boost than others in these situations and the effect can be worse or not. Or it can be boost and throttle control at low load, the drive-by-wire throttle can do some odd things from time to time, or the boost in part throttle conditions too. It would be more noticable on a PPP car as it runs more boost in general, so could be running quite a reasonable amount of boost at say 2500rpm.

It could be a lot of other things too, but a trip to a mapping specialist will probably reveal more about what's going on than ten trips to the dealer.

iuchabar

Zen - thanks guys, much appreciated, I think a trip to a local mapper is on the cards... funds allowing... laterz, Chris.

weatherman

Well mine was still in slow mode after a couple of weeks, then I had to stop at a BP garage a few days ago and for the first time since owning the car was forced to put in BP Ultimate instead of V Power. Straight away the boost seemed to be back to full strength. However too soon I thought for the petrol to be responsible.

Still for the rest of the 100 mile journey the boost was fine, as it was on my next journey today ---- for a while. Then the hesitation at part throttle at 2000rpm got worse and full throttle low-mid range acceleration was back to half what it should be.

From these symptoms I am inclined to rule out a leak or a faulty fuel pump, as I would not expect these causes to magically disappear after a petrol stop.

I suspect a dodgy sensor of some sort, which is preventing the ECU going into open loop. I think the petrol stop maybe reset the ECU and maybe the sensor behaved fine until today's journey.

If there is anything wrong with my "little or no experience mechanic" logic then please feel free to correct me!



Stuart

iuchabar

weird about the fuel?! never heard that before?
i am now 99.99% certain that my issue is the ECU map... talking to various "gurus" and because the MAF & fuel pump replacements seemed to cure it for a while.... but now it's starting to come back which suggests the ECU is being cleared at reset, then slowly going back to fault mode over time (for whatever reason).
so.
i will be contacting Subaru again, see if they can get it sorted with Prodrive... but i have my doubts... i can see a remap to 'open source' at my expense being the eventual fix.