my new car

[martinjs]

Erik, you have 3 vacum connections on the back of your inlet manifold where your red line starts in your pic behind the engine, 1 goes to the fuel pressure regulator (under the inlet manifold), 1 goes to the ecu, with a T off to the diff lock, and the other comes to the front of the engine and connects to your dump valve (a round black valve below the turbo) if any are not connected you wioll have a problem.
but your getting 0.8bar so for a standard car that is ok.
try changing your fuel filter, they are really easy to do on the coupe and are fairly cheap, a blocked one will cause lean running.

martin

[Erikb]

First of all I have seen the dumbvalve It is connected in the pressure hose that goes to the IC. One end of the dumbvalve is inside the pressure hose the other one goes to the hose which runs form the airfilter into the turbo. There is NO small hose connected to the dumbvalve, does it have to be connected on the topsite of the dumbvalve, the small niple.(could it be that they fitted the small hose on the wastegate?, could this cause problems). Many of these hoses are very old and stiff some of the show some cranks.

The place where I work use a lot of pressure hoses till 10bar, they buy them by company calles Festo, here in Holland it is one of the leader in pneumatic. Do you think I can use these hoses to replace the old worn ones.

www.festo.nl

[martinjs]

ok erik,. the small hose should be connected to the dump valve NOT the wastegate. this will be causing problems, its worth renewing all the small vacum hoses whilst you are there, check the dumpvalve itself, the diaphram inside can split.

martin

[Erikb]

Thank you martin

Someone really did not understand the car when he was trying to "repair"it. I will disconnect the hose from the wastegate and connect it to the dumbvalve on the top side. I will also open the WG and see if everything is right. I will clean the MAF sensor and the lambdasonde (can this be cleaned). And try to get the blinking codes from the computer.
I also dont have a hose/pipe for cold air feed, there is nothing connected to the airbox, maybe I can fix this with an aluminium flex pipe for a while.

When I have done this I hope the car will drive fine.

[martinjs]

Your car may be chipped after all, if you are getting 0.8bar with no vacum line on your dump valve!

martin

[Erikb]

Maybe Martin, But can you explain why there is a vacum line on the dumbvalve.

[GandalfS6]

Maybe Martin, But can you explain why there is a vacum line on the dumbvalve.

The diverter valve is connected between the Turbo to IC hose and the MAF to Turbo hose. If you get off the throttle (to change gears for instance), the DV is supposed to release boost into the MAF to Turbo hose to stop the turbo from stalling. The little vacuum line is there to open the DV when that happens.

If it was not connected the DV would not open as it should when releasing the throttle. Maybe this caused the turbo to glow as it would stall each time you released the throttle? You should now find much less lag after changing gears.

[Erikb]

The diverter valve is connected between the Turbo to IC hose and the MAF to Turbo hose. If you get off the throttle (to change gears for instance), the DV is supposed to release boost into the MAF to Turbo hose to stop the turbo from stalling. The little vacuum line is there to open the DV when that happens.

If it was not connected the DV would not open as it should when releasing the throttle. Maybe this caused the turbo to glow as it would stall each time you released the throttle? You should now find much less lag after changing gears.

Thank you for the explanation Gandalf,

Is it possible that this also solfs my other problem, a decrease in power in high revs.

[GandalfS6]

Thank you for the explanation Gandalf,

Is it possible that this also solfs my other problem, a decrease in power in high revs.

Let us know if it improves things! I also suggest you replace your DV if it hasn't been done recently - these Bosch DV's don't last very long and they are pretty cheap (GBP12 for a S3 DV from VAGPARTS - the S3 one works better than the S2 one).

[porkkis]

Yes, yes, yes. Sounds too familiar. The DV has an internal leak and that's why your car lacks performance and stalls.

[Erikb]

Yes, yes, yes. Sounds too familiar. The DV has an internal leak and that's why your car lacks performance and stalls.

I read something about turbocharged engines to understand the working of it and try to figure out what the effect can be of the hose on the wastegate to the inletmanifold and the missing of the hose on the dumbvalve.

If I understand this right, the actuator in he turbo regulates the pressure. When it is getting to high it will blow the air off threw to wastegate. So the turbo pressure will be constant. When there is a hose fitted on top of the wastegate the pressure will be blown of into this hose which run to the inlet manifold(or is there somekind of valve). If the engine is also using this air, the engine could be running lean ( this can maybe cause my turbo to glow) because the MAF sensor doesn’t detect this airflow( I am still a rookie so don’t be hard on my if I say something that isn’t right).This can maybe also cause the decrease in power in higher revs and can cause very big engine problems.

If I understand the dumbvalve right this will open when you step of the gas, for example when you shift, there will occur a vacuum which will open the dumbvalve (because there is still pressure in the system the opening will not take to much effort) and release the pressure back in the system again ( isn’t this a problem for the MAF sensor because the output will be under the MAF sensor ?). So the turbo will keep on spinning. At the moment my dumbvalve doensnt empty the system so the pressure will stay in the system. When I shift, there are no exhaust gasses that will let the turbo spin. So it will real rapidly slow down the turbo, because of the pressure that is still in the syssem behind the turbo. Can this kill the turbo?. Also it will take a while to get the turbo running again to make some pressure, so the lag is bigger at the moment.

So when I install the hose on the dumbvale the turbo will keep on spinning and is not slowing down that fast when I shift.. The lag will decrease and the turbo will have a longer life.

Can someone tell me if this is right, I don’t really understand the turbo/wastegate/dumvalve etcc. so there might be a few mistakes.

Thank in advance

Erik

[Erikb]

No turbo expert that can tell me it the above written story is possible?

[s2avant]

Erik,

I don't think the wastegate description is quite right. The air blown off from the wastegate goes into the exhaust. The pipe on the top doesn't vent any air.

As for the dump valve you are about spot on. The MAF isn't affected as the air is redirected into the input air stream. The MAF knows it's already there.

As Gandalf said your glowing turbo could be caused by the turbo stalling every time you change gear. Every time you lift of the throttle the turbo will stall under the pressure of air trying to go the wrong way through it.

You don't seem to have any major boost leaks. I was tired last night and didn't equate your 0.8bar boost with being about right.

Have you tried taking the pipe of the wasgate and attaching it to the dump valve? This should put the plumbing right and allow the turbo to work properly.

Ben

[Erikb]

Ok, changed the hose from the waste gate to the dumbvalve. The difference is amazing, the car is driving perfect. Less lag and goes very well in high revs.

I want to thank everybody for the support and the help.


The turbo pressure goes to 0,65, I thought it has to be 0,8. Can it be that my wastegate spring is to soft?. When I hit full throttle the turbo pressure goes immediately to 0,5 bar, then it goes gently to 0,65 bar. Not at once.

[martinjs]

erik, you could have a leak somewhere then, check all the hoses from the turbo right upto the throttle body, there are quite a few places which can leak especially on a 13 year old 3b BTDT , check the intercooler o-ring too (the bumper will have to come off to get to it) fit the 'mark h intercooler mod' a 70-60mm reducer hose instead, those o-rings are s**te.
glad to hear its a lot better anyway, is your turbo still glowing?

martin