Wastegate

[swright]

I bought this car knowing it had issues and would need money throwing at it etc but that's part of my passion for cars. I love sorting them out and getting them up to a standard I'm happy with.

Anyway, the car has always had a slight surge/judder as the turbo first spools up. I fitted a boost enhancer today and it only seems to have made the problem worse. it also isn't bringing full boost in any sooner. It is however making the turbo spool up to 1 bar almost instantly making the car feel better to drive round town and giving it much more torque meaning i have to change down much less often.

Would i be right in thinking my wastegate is basicaly knackered?

Also the car is massivly over fueling, chugging black cluds out at times. The car has been chipped so i was wondering if it may be something to do with that. When on full boost you get a very strong rich smell from the exhaust. Which is what made me think its maybe the chip over fueling.

The car is going in to to be seen by a very highly respected mechanic in the next week or so but i just thought id get some feedback from the people in the know on here in the mean time[8D]

Thanks,
stu

 

[Fen]

ORIGINAL: swright I fitted a boost enhancer today and it only seems to have made the problem worse. it also isn't bringing full boost in any sooner. It is however making the turbo spool up to 1 bar almost instantly making the car feel better to drive round town and giving it much more torque meaning i have to change down much less often.

That's all a boost enhancer does. Is your wastegate knackered? Might as well ask if you have an original wastegate. It was a bad design and it doesn't age well. I'd say 100% you need to get shot of the chips if it's overfuelling. It sounds like you have no means of increasing the boost pressure to use the extra fuel that the chips are providing so you only have half the kit left anyway.

 

[Diver944]

By design the standard wastegate has a pretty weak spring that is forced open by exhaust pressure long before maxium boost is reached. What this means is that valuable boost is always disappearing down down the exhuast so the lag effect is emphasised, and the power is delivered in a gentler fashion. The boost enhancer is a nice cheap way to delay the wastegate opening too prematurely, but it can only do so much, especially on a 20 year old part which will now be incredibly weak. A new wastegate from Porsche is £££££ and still has the same problem so most people fit a 'dual port' design from either Lindsey or TiAL and then use proper chips designed to match fuel delivery with a higher boost of 1.2 bar (18psi). Make sure everything is working properly before going down the modification route, there will probably be lots of vacuum leaks and maybe minor electrical sensors misbehaving - like throttle position sensor, air flow meter etc

 

[sawood12]

The surge/judder sounds a bit ominous to me. Not in a serious way, but in a way that sounds like a tricky problem to track down - it could be fuel or electrical. It certainly doesn't sound like a wastegate issue as a leaky premature wastegate will just increase lag and in extreme cases you might struggle to achive full boost. However surge/juddering is not a wastegate symptom i've heard of before. I think what Paul has said makes sense in that you should give the engine a damn good look over to look for boost leaks, any electrical problems - for example are your HT leads the originals? If your wastegate is the cars original it will almost certainly be way past its best.

 

[swright]

The last owner replaced the leads with some splitfire things not long before i bought it.(trying to sort the problem no doubt,LOL) but the coil lead was wrong so is still the original. One thing i have noticed is that a few of the leads are touching the metal intercooler pipe. Could they be arching up onto it? When its on full boost it is fabulous, its just before it boosts that it seems to judder twice then its off like a rocket. but then there's the over fueling issue which could be the problem also. I'm now thinking the chips need removing like Fen says as it might all be down to them causing the problem. The trouble is, i don't have the originals to put back in!!!! I need to book it in to see my mechanic basically and hope for the best!! Stu

 

[swright]

just had a thought. I noticed a slight leak from the manifold the other day!!!!!!!!!!!!! Im so thick ffs!! That would surly cause the problem im having by causing not enough pressure to build up in the system !!!

 

[Fen]

You can get stock chips relatively easily. If nobody on here has a spare set they want to offer then speak to Rick as I think he has some.

 

[swright]

Cheers for the info Fen[8D] Do you thing the manifold blow would cause the judder when the turbo kicks in? Stu

 

[Fen]

I would doubt it. I really don't know what to suggest on the surging. My best guess is that it takes a little while for the turbo to start making enough boost to burn the excess fuel efficiently so when you open the throttle you effectively partially "flood" the engine with fuel. The manifold leak would exacerbate that issue through making it harder to build boost though I guess. In terms of arcing leads, open the bonnet in the dark with the engine running and you'll be able to see if there is a problem.

 

[swright]

Another question. When i fitted the boost enhancer i noticed that the pipe from the banjo bolt on the intercooler pipe had a little metal insert that was loose inside the pipe(IE i could pop it out with a screwdriver). It has a little hole in the middle of it so basically it reduces the air flow. What is the function of this insert and is it necessary? Stu

 

[Fen]

Sounds like part of your "chip" kit. It will be a restrictor intended to mask the actual boost pressure from the boost control system so the car can run more boost It sounds like the kit is pretty crude, which isn't to say it wouldn't have worked once up on a time, but from what you describe it doesn't work any more and I doubt it was ever very good. I suspect you have found the rest of it though - it will be a chip to increase fuelling and a restrictor to fool the car into running more boost.

 

[swright]

Excellent, many thanks Fen[8D] Il be taking it out along with the chip as soon as i can. Once i get it all ship shape and air tight il be buying a pucker chip upgrade and a duel port wastegate as well. Dont ya just love sorting out other peoples feck ups!!! LOL!