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Another boost thread.....

H

homesea

New member
Still trying to sort a few little issues out. I have had the exhaust studs from the turbo replaced as one had snapped and the exhaust was blowing. But the car started what can only be described as missing badly. Euro and Porsche (who have been very good) found the TPS to be faulty as the car would run fine with it disconnected but would only boost to 1.2 on the gauge and idle at 1200rpm. I have today replaced the TPS and the car idles spot on and drives fine until you start really putting your foot down. Then it starts missing again but not aggressively more like the boost is on then off then on.

So my question:

Is it possible if the wastegate is old and worn out that it could have the above effect?

I was thinking it was electrical but if you make the car pull in a high gear from low revs i.e. its under very heavy load it doesn't miss, it only does in under high boost conditions.
 
Tom,
If you suspect that the wastegate is the original it is probably a safe bet to say that it is well and truely fubared. I gather the springs get weak and don't allow the wastegate to open properly causing more lag and generall poor operation.
I don't think it is a particularly hard job to change and newer dual port ones have been designed to overcome the weaknesses of the original.
Promax/Jon Mitchell would be a good place to start.
 
How long since your fuel filter was changed - fuel starvation under high demand scenario?

If you still have the original wastegate, then I'd echo that it is a good place to start...

Good luck & let us know what you find[:)]
 
Nick, I was thinking it might be fuel as well. But I think I can rule that out as after taking the car out today I noticed every time the car 'missed' or I think a better way to describe it is 'hold back' I could see a lot of un-burt fuel come out of the back.

So it's not a lack of fuel, I am thinking it's not the wastegate as this would just loose power gradually not hold back then go then hold back etc etc. It must be the air flow meter.... What do any of you think?
 
Process of elimination but I'd check the inside of the dissy cap and the rotor arm as if they are old and worn, you may not be getting the spark you need at higher revs/load? The rotor arm on mine was pretty tired when I had a look, hence changed the cap & rotor. Cheapish starting point![:D]
 
I'd agree with the electrical suggestion. I expect the wastegate will be well and truly flaccid, but I doubt that it's the cause of this particular issue. Check the dissy and also look for shorting from the leads / dodgy plugs etc.

AFM is another possibility, but they tend to give trouble around the lower speed range when they get dicky, as that's the bit of the track that gets worn most quickly.
 
Yes I was thinking electrical, but car has good histroy from Jon and Promax, also I had cap off not long ago and all looked good and new.
I un-pluged the temp sensor next to the TPS this morning and drove to work, the car runs a base map so will only boost to 1.2 bar on car dail but run fine. Anyone know what this temp sensor does? I was thinking it was to do with the turbo water pump?
 
Yeah dizzy cap and HT leads were new last year from memory. Only thing I could suggest to Tom was the wastegate as its the old one that was on my current car before I switched the Promax L2 kit between the cars. Seemed fine on my current car though it was operating along with a boost enhancer which could well have masked problems.

If folk dont think its that am at a bit of a loss as she was running fine last time I drove her (albeit she had the L2 kit on then).
 
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