Strange idle connected exhaust vibration

[220bhp]

Lou, what kind of diverter valve are you running? If it's a stock black plastic one, maybe the diaphram has split.

John at first it was a new turbosmart plumb back from s2 bo.then to rule it out I fitted the forged one,which was on the done car,it performed the same.

[twoqu]

And its a recirculating one not dump to atmosphere? Correctly orientated?
To be honest we need to suspect anything that deviates from standard. Just because you replaced one with another doesen't mean both were not knackered/incompatible. Don't the Forge ones have sticky pistons etc? Might as well just stick a 710N in there.
When you put the car back to stock that should have ruled out the mapping. Therefore the only things left are sundaries or a mechanical issue. Its a pain to methodically subsitute things one by one to eliminate them but in the absence of anything coming to light during our exhaustive testing, I cannot see a way forward.
If we knock off the easiest things first, then whatever is left at the end will be the culprit! So you will have to sit down, work out where the differences lies, put it back to stock and try it.
Whilst it would have been easy to point the finger at the mapping, we have to concede that as its the same even with the std ecu the problem is somehow with the car.

[twoqu]

What about the actual Maf to turbo hose. If that is split it could be sucking in air that the Maf hasn't seen!

[220bhp]

the turbosmart was new and I tested it of the car,and having read afew threads,tried it in both orientations,apart from the sound it made the wrong way round,which I did not like it seemed to work the same both ways.
rthe forged one is not new but it was ok when I tested it.I have A n710 so I will try that.
The samcos are new but I will check them.
You are right I have to go through every possibility and log everything I do,can;t remember half of it.so I will have to start a log.
Many thanks for your help once again,much apprecciated

[djh]

The forge dv's leak air quite often so i'd stick the 710 on it and try that.
Turbosmart valves are good, i've had one before.

Stick with it, it will be worth it in the end

[newsh]

We need to look atr all the ways that air can get past the throttle plate, that's why I wondered about the DV, if its a diaphragm type and it's split then it can leak past the TB and it won't show up ibn a boost leak test because you're pressurising both sides..

[220bhp]

Here is a video of the problem at last!

http://www.youtube.com/watch?v=EnHpgMsH8ig&feature=plcp

[220bhp]

the video shows the problem at 1450 revs,but it is only part of the problem below 2000revs.After that the car runs well

[Greg_S]

Ive lost track of what has been covered on this now, but worth checking when it starts hunting if its the idle valve sticking. I found that on mine a while ago as the cause of a very similar issue, tapping the ISV body unstuck it for a while. http://www.youtube.com/watch?v=6_-vYqGiphk&feature=plcp see last 10 seconds or so

[220bhp]

Love the hammer bit Greg.I feal like taking a sledge hammer to mine:beat.I have fitted three on the car.but I like the idea of hitting it with a hammer,so I will give it a try

[Greg_S]

Yeah its worth a try, it took be the best part of a month to diagnose this along with other issues I was having and once I fixed the broken insulation, a bad connection and replaced the ISV all was well.

[220bhp]

Hammer test made no difference,had to suppress the desire to hit it harder:beat
I let my wife drive me around in the s2,so I could try and keep an eye and ear out for anything.She drives everywhere under 2000revs,which is right in the problem zone with this car.After cruseing for a while on country roads,I noticed that the temperature had gone up,and also the oil temperature was quite high,so I took over and drove the car home,soon as started to drive the car at above the 2000rev range both temperature gauges returned to normal.This makes me think that the car is running lean at below 2000revs which is not good.So what if this is the case would cause this other than the things that have already been checked.
Todate the only things that I have not checked are FPR, wastegate,and timeing.I have checked the waste gate diaphram and spring but nothing else. If it is a vacuume leak then I cannot find it.
If it is fuel starvation then why does it only appear at below 2000revs.I have a bosch
044 fuel pump fairly new fuel filter,but I guess I can't rule them out same go's for the 7a FPR.How do I check these.
The other thing is timing if it was distributor alighnment it would not boost. and It does
Would the timeing cause these issues.
That only leaves the wastegate or something I am not taking into account. any advise would be much appreceated

[220bhp]

Had another go at trying to find the problem with my car by rechecking all the vacumme hoses and discovered that by pinching the pcv hose that runs up and round the back, I can get the idle to slow down,the more I nipped the hose the lower the revs, until it stops the engine.
I am not sure if this is supposed to happen or weater it indecates a possible leak in the pcv hoses that I have missed.

[220bhp]

Would appreciate it if some one could just try nipping this hose a little on there car and see what happens,before I start stripping my car down.

[newsh]

Definitely seems like you have a vacuum leak which as you say is making it run lean when off boost, have a look at the PCV diagram below, it is for the ABY but is basically the same, just that the 3B has the metal pipe running alongside the cam cover next to the charge pipe and the ABY pipe is hidden inside the cam cover.
There is a one way valve (check valve) between the inlet manifold and the PCV system which is hidden in the join between 2 pipes of different sizes below the TB. This has to be working correctly. The connection from this to the IM is underneath the IM and pointing back towards the bulkhead. You should be able to disconnect this and bung the end then put a short piece of hose on the IM side and bung the end of that and clip it. The car should run fine like this. The only thing that won't happen is the Carbon Can will not get purged.

Unfortunately I don't have this hose on my car as I have a catch tank instead of the PCV system.