Fat Blerk

Any advice welcomed!!

Recently had full de-cat and induction kit fitted on '99 RB5 WR. Excellent performance gains.........followed by MAF sensor failure. Symptoms - idle problems, apparent fuel-cut on an open throttle around 5000RPM (occasionally). A run with a borrowed boost gauge showed boost levels of 1.1 bar, spiking to 1.2. I changed the MAF sensor (many thanks to Graham Goode!) and sorted the idle and (I thought!) the overboost. The car didn't feel quite so manically quick, but no problems......until today. Once again, what feels like a fuel cut while under hard acceleration - just once, but enought to concern me.

If it is still overboosting (de-cat + induction kit??) how can I control it without de-modifying the car (cos I LIKE this performance!!!) Help!!

john banks

Sorting out the overboost (if that is what it is now doing, and quite possible with PPP/decat/induction in the cold) will reduce the performance in the lower gears in particular, and spool up rate "punch in the back" will be degraded. There is a long thread from me in Drivetrain from a few months back about a flow control valve replacing the restrictor if you first make sure the restrictor and solenoid are clean.

Fat Blerk

Great! I'll dig it out. Many thanks JB. One other question........ if you'd be so kind.......... if I leave it as it is, is it safe? I assume the fuel cut is to protect the engine, but is it enough? may leave it alone if it won't lead to a more serious problem.........

john banks

A boost spike can cause det so you can't assume it is safe.