john banks

Well, it was overboosting, could see it on the select monitor after flooring the throttle from 2500 in 3rd. It went up to 1000mmHg (19.3PSI) pretty sharpish, then dropped to 750mmHg and then maintained around 850mmHg. The boost cut off is at 1000mmHg. Apparently on later cars, the overboost cut off is not like the abrupt slamming on the brakes and is smoother. Which is why I didn't think originally it was overboosting. Dealer thought that standard restrictor was 1.2mm, so we tried 1.3mm and it felt slow but did not overboost and was very smooth in power delivery. Still quicker than pre-PPP but a bit disappointing, and this on a hottish day, so really I could not have lived with the degree of overboost that it had on (presumed 1.2mm). Apparently there is no easy way to tell the size of it! New WRX has 1.2mm restrictor so one of those was tried next and it overboosted as originally. So back went in the 1.3mm one. After driving it a few miles, it seemed to come right with power delivery just as ferocious as the original restrictor without the jerkiness/overboosting. A few timings of increments revealed no difference than with the 1.2mm restrictor, but the spool up was always perfectly smooth with none of that oh, that's a bit disappointing feeling it had when overboosting. After a few miles it was holding 860mmHg (16.7psi) with the initial boost up to about 930 (18psi) - so there is actually more held boost than before (!) with only a little less peak boost. The lack of the overboost stodge must make up for that as the car feels more sorted than ever. I hope the 70mmHg(1.4PSI) manifold pressure leeway until overboost is enough to take it through a few cold mornings!

Dealer said they did NOT think that a panel filter and DP would make it overboost again.

Hope this is all helpful/interesting to those with truculent PPP'd cars. Now a happy bunny. Now where is that number for Falkland for a Grp A pipe and Scoobysport for an ITG panel filter??

[This message has been edited by john banks (edited 17 August 2001).]

NM

Glad to hear you have got it fixed.

Happy driving mate

Neal