Boost leak time from 100Kpa to 0Kpa

[orsum]

I was quite shocked at how such a small leak affected the cars performance. If the leak on the ISV N71 when fixed has the same effect I will be a happy man.

The idle of the car it good so I am not sure at this stage what will happen when I sort the IVS leak but I hope it will be the last one I have for now.

[Mr G]

Thanx for sharing and glad you found them......the leaks that is

[orsum]

Found two

It seems like with all the work we do it keep our cars in top condition there is always something else waiting to give you grey hairs

[Mr G]

I hear you.........all my hair is grey ....

[Rikki Kitto]

Nightmares but when they run right what a blast ?

[orsum]

The ISV with the end filled with Epoxy.

Hope to fit it today.

[orsum]

ISV fitted and working no leaks

Trouble is I still have a problem.

[orsum]

Let me start all over with what happened and what I have done. S2 upgrade to RS2 spec. The car was running ok before this event.

I was doing about 220kph and a bike pulled in front of me. I took my foot off the loud peddle and then quickly put it back on. instantly I had a problem. It felt like a misfire and the car lost lots of power. basically anything over 0 bar and the car felt like it was misfiring. I can get the car to any speed I like as long as I keep the boost below 0.1 bar the car runs smooth. Go above that and the problem starts to appear.

1 Checked for a coil pack or plug fault. No faults found all ok
2 Checked for a boost leak with my little compressor. Found two leaks not big leaks but I found two both fixed.
3 Took the car to a friends place who had a better compressor that could hold 1 bar. Again found two more leaks petrol regulator vac pipe and ISV. Both fixed.
4 MAF connection check and in order.
5 Unplugged the N75 and the car boosted to 0.4 bar before the WG opened.
6 WG diaphragm checked no leaks

After all this I still have a problem. All the work I have done has "slightly improved the performance" but the basic fault that appeared that day still exists. The N75 is operation at anything above 0.4 bar. The car battles to get to 1.9 bar the N75 is basically operating all the time pulling the boost via the WG. I feel that something failed that day but I have no idea what.

The faults I have already found in my opinion did not happen that day which is nice because when I find this fault the car must go much better

Any thoughts

[newsh]

Did you check the diaphragm in the Diverter Valve? I explained how to do a wick check further up the thread.
Actually you don’t even need the compressor, just pull the vac line of the front of the manifold, it should hold vacuum.

[orsum]

Sorry I forgot to add it to what has been done.

Yes I did test the DV. It held a vacuum DV was fine. I had a new spare so just to make sure I also replaced it. I also tested the new one it also held a vacuum.

Also tested the small none return Valve (Bleed valve) it leak a small amount so I replaced it with a new one. Tested after fitting and it was ok.

[orsum]

I just checked the spark plugs fitted and they are the Bosch FR5DP. I have lost my feelers so I cannot check the gap a couple look a bit big.

Gee I hope a misfire under load is all that is wrong. Idle is great up to 0 boost the performance is great.

Just placed an order for five NGK BKR7EIX and a feeler gauge. Hope to get them next week.

[Mr G]

Hi Orsum, just fyi - I managed to resolve my intermittent boost issues, after replacing all the small bore vacuum pipes - not sure if you’ve replaced yours….
I’ve always had the F5DPOR plugs since getting the car in 2008 and never had issue
Good luck - hopefully the problem is resolved after the plug change
Cheers


Sent from my iPhone using Tapatalk

[orsum]

I did have some pipes replace but I will be going through each pipe one by one to replace the ones I have not done and checking the ones I have.

I always thought once you fixed a pipe leak then it would not leak any more. With what I recently found that does not apply to an Audi S2 vacuum systems

Not sure the plug change will do the trick. The only reason I am changing them to NGK is I am a bit worried about what has been said about the quality of the plugs and the damaged they have caused to several engines.

Even if I resolve the issue by changing the plugs I will still be replacing every pipe in the car.

[orsum]

So I said

Not sure the plug change will do the trick. The only reason I am changing them to NGK is I am a bit worried about what has been said about the quality of the plugs and the damaged they have caused to several engines.

Need to keep my thoughts to myself.

Yes I changed the Bosch 19,000km old spark plugs to NGK and all the boost loss and hesitation has gone. The NGK are set to 0.63mm

How nice it is for the car to pull like I stole it. I will still be changing the hose that I have not done and checking the ones I have done.

The small leaks I did find and fix while looking for the boost/spark plug issue has added to the overall performance of the car and all I can say it feels great.

[Mr G]

That is "awesome" , I need to keep this in mind, for the next plug change on mine. You must be chuffed....... well done!!!