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Quick answers about possible overboost needed please

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Old 07 January 2001, 10:20 PM
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Rikki23
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Question

I know that this is in the wrong forum but I needed some quick suggestions and I guessed more people would look here.

My MY95 WRX is going in to Lavender Hill to have the exhaust heat shield replaced on Tuesday. I have told them that my car is overboosting too and asked them to look at this. But I am not sure if overboosting is what it is.

This has been spoken about a lot before on here I know. I have printed off all the search results in the archives a while back (when searchit was working) and I have just read through them all to get ideas of what the dealer could do.

I am now not convinced if it is overboosting. I read something that said overboosting "pushes a big chunk of extra air in to the engine" which is different from "boost cut". My engine is dying very suddenly under hard acceleration in 1st and sometimes 2nd (never 4th or 5th) but my guage only peaks at 0.9 Bar, which does not sound tremendously high for a WRX. So could this be (premature?) "boost cut" rather than overboosting from too much boost? (I don't know an awful lot about this!!)

Has anybody got any experience of proven solutions for this. I have read various things in my archive searches. Cleaning (or even replacing?) the solenoid and pipework leading to it seems to be popular. I did notice that when I bought the car the oil level was high but that is OK now. I have also read a few things about restrictors of varying sizes being fitted and experimented with. The last thing I want is to lose any power, I am scared that the dealer might do this - I would rather have the power as it is with this problem, than lose power.

Could/should I be able to run more than 0.9 bar safely on my WRX?

I need some answers before it goes in on Tuesday and I would be very grateful for any help or advice.

Many thanks
Rikki

Old 07 January 2001, 10:50 PM
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WALKER
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Rikki

You should be able to run more than 0.9 bar safely. Most of the Sti`s run about 1.2 bar peak that i know of. Mine runs 1.3 bar peak although it does run Unichip.

You may have picked up some oil into the boost control solenoid valve, which could be stopping the car from boosting(bit like hitting on the brakes hard, similar to overboost). This can easily be sorted by removing it and cleaning with brake fluid.

Anyway your dealer will sort it out, and i doubt you will lose power.

Paul
Old 07 January 2001, 11:31 PM
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Bob Rawle
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Early cars only run 0.9 bar standard and the boost cut is at 1.15 bar, they had a much bigger turbo so didn't need the boost. You are hitting the boost cut probably due to the colder weather, quite a few are at the moment. Interesting that its in 1st/2nd, you have a sleeve bearing turbo so normally this only happens in the higher gears, maybe its not helped by your driving style (no offence), try rolling the throttle more instead of punching it, see if that stops it, in your case the solution would be to change your restrictor (in the solenoid vent pipe) for one with a smaller hole. This is not to be confused with the later cars when a larger hole is needed. If the restrictor on any model year has to be modified to stop overboost you will lose power when the weather warms up, be a good idea to keep the original restrictor so it can be re-fitted when that happens.

Bob
Old 08 January 2001, 09:12 AM
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Rikki23
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Bob

I have had the car since October when the weather wasn't that cold and it was doing it then. The car had been to Lavender Hill before I bought it I think and after reading the archives I checked the oil and found that it was too high. It is quite frustrating when you just want that bit of quick acceleration and you put your foot down then it 'hits a brickwall'. Don't need it all that often but frustrating when it does happen.
I don't really want to get in to swapping things around/playing under the bonnet too much at the moment because my technical knowledge is quite limited at the moment?


Teknopete

I believe 22psi is about 1.6 BAR !!
Old 08 January 2001, 12:28 PM
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teknopete
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Rikki,

I run 22lb boost on a 93 WRX without probs
Dunno what that is in bar but hey thats it in British money Jus outta intrest whats the conversion figure? (duh).....


[This message has been edited by teknopete (edited 08 January 2001).]
Old 08 January 2001, 03:40 PM
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Rikki23
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can anybody else help me out??
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