Hesitation at WOT and 30FE overboost

[yawn]

I'm hoping the collective mind of the forums can help.

Starting with the hesitation issue, I first noticed it about 3 months ago. Since that time, I have undergone walnut blasting, had my coils, plugs and injectors replaced. Still, there is no resolution. I still have the hesitation - it is almost the feeling of traction control kicking in. Logs will show rpms climb before dropping a couple hundred rpm, and then picking up again. Very noticeable in the car.

http://datazap.me/u/shark/hesitation?log=0&data=1-20

Log has been done with traction control off.


My other issue is with overboosting (30FE). This only happens when the car is hot - for example if I go to the race track. I don't go anymore because of this problem - you do 2 hot laps, and then 30FE pops up, reduced engine power, etc, etc... go home early. This is a log of when the code actually happens - notice the small rpm hesitation too at the time the overboost occurs.

http://datazap.me/u/shark/overboost?log=0&data=7-20

I have changed all my vacuum lines including the ones to the turbos. I have tried swapping out my vacuum solenoids with a known working pair. Still happens.

I really suspect both issues might be caused by turbos that are going bad - but I want to be sure before I dive in. Anyway to check or log for wastegate activity during a run to cause the code? Is it possible for the high heat to cause the wastegates to stick shut resulting in boost issues?

[PG]

just a simple thing I tried was removing my procede/jb4 if you have one? Can't hurt to try...

[martymil]

Do a vacuum reading when the engine is hot.

Disconnect the vacuum line between the two solenoids

Block one end and do a reading on the first solenoid
And do the same for the other

You have to have them isolated from each other when your doing the reading.

Also check the vacuum on the canisters as they could be cracked

The vacuum reading should be identical on both, if not
your going to need some new ones

Btw the new ones are very different from the originals

I've changed mine and never got an under boost or over boost ever
again, and my turbos where always tapering down to
13 psi in fourth, after I changed them solenoids I could hold 17 psi in fourth on stock turbos at the drags

When they get really hot they leak internally

Have you tried lowering you ff adaptations to 70 and let it learn up from there

[yawn]

Originally Posted by PG_DC5

just a simple thing I tried was removing my procede/jb4 if you have one? Can't hurt to try...

Yeah, I've also tried reverting back to stock (currently Cobb protuned) - still having the same issues.

[yawn]

Originally Posted by martymil

Do a vacuum reading when the engine is hot.

Disconnect the vacuum line between the two solenoids

Block one end and do a reading on the first solenoid
And do the same for the other

You have to have them isolated from each other when your doing the reading.

Also check the vacuum on the canisters as they could be cracked

The vacuum reading should be identical on both, if not
your going to need some new ones

Btw the new ones are very different from the originals

I've changed mine and never got an under boost or over boost ever
again, and my turbos where always tapering down to
13 psi in fourth, after I changed them solenoids I could hold 17 psi in fourth on stock turbos at the drags

When they get really hot they leak internally

Have you tried lowering you ff adaptations to 70 and let it learn up from there

Hmm if they are that different, I might just replace the 2 solenoids then. Should be easy to do right? My concern however is that I'm not losing boost - I'm getting too much - overboosting. Instead of not closing somewhere, it is not opening to release the pressure. Could it still be the solenoids?

Also, with regards to testing the vacuum canisters, you just plug the gauge into the top of them one at a time?

Thanks

[yawn]

Also, what could cause the brief spike and hesitation of my rpms in my logs?

[martymil]

Yes to test the canisters just unplug the top hose and test

Yes probably best doing both if the test fails

They are not cheap

No coding needed either

So no jb4 just Cobb ?

Definetly sounds like or could be a combination off

Small vacuum leak
Canister crack
Or vacuum lines behind the oil filter

Best bet is to get a vacuum gun and create your own vacuum to test for leaks

[martymil]

I looked at your logs, it looks like the rpm spike is either wheelspin or transmission is slipping at peak torque

Put your car back to stock tune and run it up on a dyno to see if its still happening

how many km's you done

List your mods

[Dackelone]

Originally Posted by martymil

Yes to test the canisters just unplug the top hose and test

Yes probably best doing both if the test fails

They are not cheap

No coding needed either

So no jb4 just Cobb ?

Definetly sounds like or could be a combination off

Small vacuum leak
Canister crack
Or vacuum lines behind the oil filter

Best bet is to get a vacuum gun and create your own vacuum to test for leaks

A cracked valve cover would also cause a fair vacuum leak.

[martymil]

The n54 turbo line vacuum runs of a vacuum pump and not the engine as far as I know, I cant see how a cracked valve cover could cause and issues except for the pvc system.

[yawn]

Originally Posted by martymil

I looked at your logs, it looks like the rpm spike is either wheelspin or transmission is slipping at peak torque

Put your car back to stock tune and run it up on a dyno to see if its still happening

how many km's you done

List your mods

I'm about 90,000km. Mods include charge pipe, Forge dvs, intercooler, dps, RB pcv.

I had also wondered whether it might have been my clutch slipping - but if it was why would it suddenly hook up after a slight miss? It's not like I abuse the clutch either. Don't think it is wheel spin either - had traction control off at the time.

Plan to go back to stock and see if it still happens.

Thanks.

[martymil]

That nails is your clutch can't hold the power anymore and is on its way out

When it spikes that's when you are hitting peak torque and when it hooks up again and the sudden jolt of the hookup of your transmission is making it boost spike for a split second

You need to put it on a dyno to confirm but especially in low gears where the torque is in its highest its slipping a bit

At stock power levels it shouldn't slip but tuned the sliping will be more evident

There is nothing wrong with the vacuum by the looks of it

If it was auto I would say check it out but manual it's almost a no brainer that its your clutch

[vtl]

Clutch testing is easy, stick it into 6th gear at 50kph. Go WOT and if the clutch is slipping the revs will rise much faster than the car is moving.

[martymil]

Really depends how bad the clutch is, I recently saw a car on a dyno had a slipping clutch but on the road it was ok.

[yawn]

Originally Posted by vtl

Clutch testing is easy, stick it into 6th gear at 50kph. Go WOT and if the clutch is slipping the revs will rise much faster than the car is moving.

In 5th gear and wot from 60kph the car will start to accelerate, then once 2500 rpm is reached it will start to rise much more rapidly than the speed I'm traveling at for half a second or so. Then rpm will fall slightly before resuming normal rpm increase. Once it steadily reaches 4500 rpm it happens again.

[vtl]

Originally Posted by sharkatron

In 5th gear and wot from 60kph the car will start to accelerate, then once 2500 rpm is reached it will start to rise much more rapidly than the speed I'm traveling at for half a second or so. Then rpm will fall slightly before resuming normal rpm increase. Once it steadily reaches 4500 rpm it happens again.

definitely need a new clutch.

[yawn]

What kind of dollars are we looking at here in terms of clutch replacement options? I have read that it is a good idea to change the flywheel whilst you're at it.

Currently looking at Spec 2+. But trying to source locally - USD is killing us and the shipping costs are crazy too.

[martymil]

Talk to advan performance or jd75 on the forums I know they done a hd clutch for a guy recently and he seems to be very impressed with it.

[vtl]

You can save some money by going for a single mass flywheel. This will be lighter and allow your engine to spin up faster but may introduce chatter.

Not sure if you'll be able to reuse your dual mass as they can be quite tricky to machine.

Some people also go for a 550i/335is clutch which is compatible and can handle some more torque. An OEM clutch will have easy takeup

http://my1series.com/2015/03/23/335i...lutch-upgrade/

[DR-JEKL]

I recall extreme clutches were offering a N54 clutch setup also, eurohaus at castle hill were distributing them.

[yawn]

Originally Posted by DR-JEKL

I recall extreme clutches were offering a N54 clutch setup also, eurohaus at castle hill were distributing them.

Thanks dr-jekl. Will look into that too.

[c0ris07]

I have the exact same problem. Just changed a cracked valve cover on the weekend as I had oil leaking into my plugs. While I was there I did new plugs, coils, vacuum lines, boost solenoids.

Havent had a chance to go for a proper drive yet but I will let you know how I go getting rid of the problem.