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Old 09 Aug 2006, 07:47 PM   #1 (permalink)
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overboost?

Hey people.,

My car started to do something weird.
in 4th an 5th gear, if I put my put my foot down to the metal the boost blips up to 1.5 and then back to 1.2 again, then back to over 1.5 then back down again.its carrys on doin this in 1 sec intervals, i can hear the turbo whistleing (doing its thing) then stopping, then starting!!.
it does this until i ease off the acclearator.
I replaced the MAF about a year ago, and i replaced the knock sensor about 8 months ago, i dont think its the maf again as i have never experianced this fault....... also could this be causing knock on my engine?

otherwise the car seems to be running fine....tried quickly cleaning the solenoid, but didnt seem to make any dif.

Also since this fault my boost gauge needle seems to be shaking slightly too.....

Any ideas guys? its a right git, cos to test sensors etc i would have to buy them first!!....

Any idea or commentd would be very greatful.

My car is turbo 2000 V reg, ppp
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Old 09 Aug 2006, 10:07 PM   #2 (permalink)
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sounds like its hitting the boost cut, aka physical barrier thats in place to stop turbo forcing to much pressure through engine and sending piston into the carageway. will be backing off to prevent damage.

might need the ecu reset to solve it, but i recomend getting it on a rolling road/dyno to make sure its not a direct fault with the ecu or some other sensor
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Old 09 Aug 2006, 10:23 PM   #3 (permalink)
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mmm...ok, i have reset the ecu anyway, didnt make any dif.......i did get a lsight metalic sound while hammering in 2nd gear, maybe piston slap because of the overboost?
Also the dump valve seems to be mucj louder too than usual.....and the turbo sounds like its kicking in way too early than it should do.............

The car is going in for an oil filter change and mot end of month, i think ill get some diags done on it...

Cheers.
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Old 10 Aug 2006, 08:47 AM   #4 (permalink)
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if its that serious i'd def not let it boost at all, drive it as little as possible, rter than risk it being seriously damaged, hope you get it sorted soon mate.
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Old 10 Aug 2006, 08:52 AM   #5 (permalink)
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1.5 bar on a PPP? far to high.
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Old 10 Aug 2006, 08:54 AM   #6 (permalink)
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tis high mate, think the ecu has lost its way, prob cos of the heat, but strange ecu reset hasn't sorted it
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Old 10 Aug 2006, 08:58 AM   #7 (permalink)
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Quote:
Originally Posted by Tidgy
tis high mate, think the ecu has lost its way, prob cos of the heat, but strange ecu reset hasn't sorted it
Strange you saying that, because its been really hot lately, for like 4 weeks, but its started to play up soon as it started to rain.........

Ill try another reset, just incase it didnt reset properly, unfortunalty i have to use the car foe work etc..........im considering get rid of now...maybe for a bmw 318..... im only getting about 19mpg out of my scoob, very wallrt unfriendly..
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Old 10 Aug 2006, 09:03 AM   #8 (permalink)
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get it checked out, if you are overboosting could be catastrophic.

Mine runs 1.6 bar on high boost & had a problem with boost controller a couple of weeks ago, hit 1.88bar, panic!!!!!!!!!!!!
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Old 11 Aug 2006, 07:05 PM   #9 (permalink)
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i dont suppose anyone has an old broken maf sensor i can buy from them? i was going to try my old sensor, as my old sensor just had a different fault, i wanted to see if i get the same prb with it......... just trying a process of elimination......... ive tried diagnostics and it doesnt give a fault code, but not suprseing as my old broken maf didnt either.....
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Old 14 Aug 2006, 05:06 PM   #10 (permalink)
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A rolling road would definitely sort this problem or at least tell you what the problem is.

If your only getting 19mpg then just stay off the boost. My Type R manages 30mpg or more
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Old 14 Aug 2006, 05:43 PM   #11 (permalink)
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Quote:
Originally Posted by Phill-type-R
A rolling road would definitely sort this problem or at least tell you what the problem is.

If your only getting 19mpg then just stay off the boost. My Type R manages 30mpg or more
cheers for your suggestion, yep my car is really thirsty for some reason, i dont have a clue why, would the dump valve be affecting this? i tend to stay off the boost allot anyway, i have tested the car driving slowly and hammering it everywhere, there only seems to be about 10 miles difference.

I noticed that the fault i have only becomes apparent if i hammer my foot the the floor,
When i put my foot down gentley its abosolutley fine......
Also filled up on tesco 99 octane today, seems a little better,
Got a oil filter change at end of month will see what its like after that.

The garage also said they could do an engine flush while they where at it? 30+vat, is it worth it?
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Old 14 Aug 2006, 05:52 PM   #12 (permalink)
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I'm unsure on the engine flush mate, as the higher octane fuel is meant to help keep it cleaner anyways (guys please help me out here if I'm going wrong!!)

When I'm over 3000rpms, my fuel is a lot worse. Its still way over 19mpg's tho, but its certainly not that bad. If your over that, the boost is kicking in, so it depends on where your changing gear and so on Try it, I manage 200 miles to 1/2 a tank

I wouldnt have thought a dump valve would have much say on the fuel consumpsion... I could be wrong..

By the sounds of it, it needs to be checked over and maybe re-mapped. It will cost, but it will definitely sort any fueling or any problems out with the car. They will know as soon as they map it if something is wrong.

Maybe a change of plugs and leads or something might also help. I would give Derek or Paul a call at Zen and see what advice they might give. They really are great with advice
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Old 14 Aug 2006, 05:57 PM   #13 (permalink)
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Cheers for your quick reply phil,
Remap sounds good, but its been done by pro-drive, does this cause a prob?
I think ill have new plugs and leads fitted anyway as they havent been done in the 2 years of woning it,
Im having an oil change as i havent done it since july 2005 (whoops). i think the oil has a massive factor on fuel consumption......

Ill keep everyone informed of what happens, as its always helpful if anyone else has the same problem in the future...
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Old 14 Aug 2006, 06:02 PM   #14 (permalink)
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Quote:
Originally Posted by dieard
Cheers for your quick reply phil,
Remap sounds good, but its been done by pro-drive, does this cause a prob?
I think ill have new plugs and leads fitted anyway as they havent been done in the 2 years of woning it,
Im having an oil change as i havent done it since july 2005 (whoops). i think the oil has a massive factor on fuel consumption......

Ill keep everyone informed of what happens, as its always helpful if anyone else has the same problem in the future...
the map isn't directly done by prodrive well it is and it isnt. prodrive have taken a car with sprts cat, high flow pannel filter and then mapped it to safe tolerances, then that generic map is applied to each car.

have a look in the scooby discussions area there a thread called impreza mods/parts, there a section on mapping in there that should help you out.

oil change is a def must, need to be every 3k idealy so its gonna be in abad state.

think tbh only way your gonna get an answer is to get it on a dyno, the more times you take it out and try it the more likely you are to do it damage, plus faults are not always what you think they might be, so you could be spending a fortune on replacing parts when all it might need is a 100 sensor replaced.
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Old 14 Aug 2006, 06:10 PM   #15 (permalink)
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I dont think there's anything wrong with the ProDrive map, but with Andy F or Paul at Zen Performance, they will tune the car to whatever it can manage, safely. Its more of a personal tune rather than a generic one...
Also with regards to the faults, have you checked the faults codes (if any) that might pop up? On my Type R (98 model) I have two black plugs that I can put together to find out if there are any sensors gone that the ECU will have logged a problem with. Maybe this might give some clues?

The plugs will help but I think the leads are pretty good (again according to Derek at Zen) as he hasnt changed his. He runs a 500+bhp Wagon...

I was just gonna say I didnt see that it had a PPP on it, but as Tidgy says it needs to get on the dyno. Dyno it first, then see what the problems are and go from there
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