Beer Good

Had a manual boost controller fitted last August set conservatively at 15 psi indicated by boost gauge (same psi as indicated before controller fitted).

Car MY99, prodrive exhaust, steel induction kit, no de-cat.

Car is much nore responsive but in 4th & 5th burying the throttle at 3500+ rpm causes horrid hesitation or flat spots. Only occasionally happens in 3rd and never in 1st or 2nd. What could this be caused by & what should I do to fix?

Also I understand you should tweak Dawes according to outside temperature, in this hot(ish) weather should that be 'down' or 'up'?

As you can tell from above, I'm not an expert!

Any sensible advice appreciated!

Cheers
Steve

555ROB

I may be very wrong here but i would say turn your boost down slightly in the hotter thinner air conditions, you need good cool air therefore a cooler charge temp in order to run bigger than stock boost on an otherwise std car.

As for the hesitation you may need to give a little more info in order for others te help diagnose your problem.

Hope this helps a little...ROB

Beer Good

Thanks Rob. Hesitation is as ... boost building 1 sec.. no boost 1/10th second.. what the.. boost building 1 sec.. no boost 1/10th second.. worry.. off throttle.

Not a good description I know but best I can describe it! In an older car I would describe as a 2 cylinder misfire followed by normal running.

Steve

greasemonkey

Induction kit of questionable quality is not the best thing to put on your car at the best of times. Virtually nothing to gain and potentially plenty to lose.
Big risk of altered airflow characteristics throwing MAF values out, together with reduced filtration causing accelerated sensor degredation, increasing the amount of underfuel in the process.

Taking boost control away from the ECU takes away an additional level of safety. That sort of scenario could easily end in tears if you're unlucky, and may already be damaging the engine, so I'd suggest refraining from driving the car under boost until you isolate the cause of the problem and rectify it.

What you're experiencing could be boost cut if your gauge isn't accurate, could also be detonation. The fact that it seems to get worse in the higher gears tends to indicate that it's load related rather than something less serious like a faulty coilpack.

Are you running a KnockLink and AFR meter, and if you are, what are they telling you? Have you noticed an increase in engine noise on the KnockLink, and/or a gradual weakening in the mixture on WOT?

For the sake of completeness, you should reduce the boost level during warmer weather, but this is assuming you set the boost level at a point just short of det in the first place.

Beer Good

greasemonkey

Lots to think about there as I go to bed. Don't like the induction noise anyway. Are you suggesting going back to standard airbox? If you could expand on the 'load related' statement I'd appreciate it! Thanks for your time.

Cheers
Steve

Scott.T

iTrader: (2)

Sounds like the MAF is dying to me. One of the symptom are hesitation when loaded.
If it's been running an induction kit chances are it has damaged the MAF (as they are very prone to this on MY99/00).
For £72 inc VAT (from Subaru) it's worth changing anyway. If it don't fix it you can keep it as a spare (which you will probably need in the longer term anyway).

If everything else if fine I doubt it is detonation @ 15psi. If it was reading 15psi without the MBC then I suspect your gauge is over-reading by 1psi+ anyway. As the Standard ECU peaks at just under 14psi.

mr smash

Try cleaning the dawes[analog] may just be cloged up with crap causeing it to stick open sometimes....worth a try.

JohnRoly

These sound like the exact same symptoms that I am suffering with. So far (under warranty!!) I have had the boost solenoid changed, restrictor valve replaced and the wastegate actuator replaced as well as replacement pipes/hoses and still no nearer to finding the problem. One guy said that the oxygen sensor was broken, but fixed it and still no nearer getting this sorted.

Any advice greatfully received!!!!

Beer Good

I agree it is unlikely to be det. Did a few tests today, the hesitation is entirely restricted to the 2500 - 3500 rpm band, as boost is building, no probs thereafter. Does that help?

On another subject, I had a flirt with an '04 BMW 330D the other day. I won in the 70 to 110 squirt, but only just. Boy, do those things shift! And 39 to the gallon @ 1500 kgs. Only thing I wasn't impressed with was the cloud of soot coming out the back of the thing! Think Scoob performance suffers from poor aerodynamics in this speed range.

Private road, of course.