I have noticed over the last few days that when I accelerate hard in my Scoob MY00UKTurbo PPP she boosts correctly (as per my Boost Gauge) but I feel at around 5K rpm a slight stutter. The boost is progressive and I feel the pull but as the revs hit 5K or thereabouts I feel almost like another slight kick of boost. It could be a slight hiccup and then boost comes back on but the gauge shows constant boost?? My AFR is showing Rich with WOT. Any ideas what this could be, I am thinking Boost Solenoid possibly ??

 

Not if your boost gauge is indicating a constant level of boost at the time you feel the "slight stutter". I know it's difficult at those revs, mainly due to speed , but you could do with also keeping a close eye on your AFR gauge, to see if it stays at a constant rich level at the time of the stutter. You don't have a Knocklink yet, do you...?

 

The AFR stays constant too when using half throttle or more - its an Autometer and reads 1 to 2 green lights into the Rich zone. It actually feels like something is sticking ?? I don't generally floor the throttle all the way but at about 5/5.5K rpm if I floor it it feels almost as if there is a slight blip ? This only happens when booting it up an incline so the car is under load. I don't have a KL as yet although this is a definite purchase for the near future. I am running standard PPP no Decat D/P and just an STI Panel

 

Didn't you fit a GBE MkII not so long back, and decat the downpipe...?

My next move would be the MAF sensor. How old is it?

Lastly, you mentioned you fitted some new plugs a couple of months ago. Are they still the same ones? You would be better off with NGK PFR7Bs to be honest. The 6s are OK, but with the PPP and higher boost levels, the 7s would be a better idea...

 

yes I did fit it all mate but ended up removing it cos I was suffering with some running problems.

At the moment its running with stock boost solenoid - i did clean out the restrictor not long ago but haven't cleaned the actual solenoid for a while...but you did say that you don't think its this. The MAF was replaced about 2 months ago as was the Lambda (it was a just in case scenario, having prev run with an ITG) I now have the Paper STI filter. I did fit some new plugs a few months back and did use PFR6's as you say - I guess the 7's would be a better idea. I still have the GBE MK2 so I could refit and see if problem is still there.

Thanks for your assistance Judge

 

You could certainly prove/disprove the wastegate solenoid/restrictor by refitting the GBE, and keeping the boost at the same level...

 

OK Fitted GBE MBC last night and took the car for a blast. Originally could only get 10psi but I had the blip as soon as the rpm hit about 4.5Kish This was in 3rd gear with WOT. I pulled in to adjust the MBC and as I did so noticed that the drivers side mat had become lodged under the throttle stop.....now I moved the mate continued on with my driving and the problem didn't seem to occur again. I find it hard to belive that the stop was causing the problem ??

 

I'd be amazed if it were that. Go back to using the wastegate solenoid again and see if it comes back...

 

I have refitted original Solenoid this morning but wasn't able to open her up - should get a chance when I go home later on...I'll keep you posted cos like you I find it hard to believe that was my problem !

 

Well on the way home tonight I needed no excuse to open her up and the problem has gone - sorted !! It was the bloody mat (I'll go and grab my coat)

 

Bizarre. Still, a cheap and easy solution. Which is nice...!

 

Well this morning - the problem returned It slightly blipped again. To explain it - I can hold boost at say 10psi with 3/4 throttle to say 5/6k rpm but if I do the same and then floor it WOT to 15 psi I then get the slight blip - Boost stays steady and the AFR shows Rich. I have checked the ECU for codes - nothing ?? The thing is the car feels fine at all other times - so I may go with one of your ideas Judge that being the Plugs....I shall get some NGK 7's ordered up and try that first....cos that is sort of what it feels like (a slight misfire)

 

So the mat was a red herring then... bugger. Plugs certainly seem to be next on the list. Make sure the gap's at 0.7mm as well...