Overboost and even Jeff is stumped...

[BlueCTTDi]

I KNEW sooner or later someone would figure it out (assuming it would be Jeff..)

I'll be very happy to implement whatever the ultimate solution ends up keep us posted, please!

 

[childishidealism]

Well I'm still looking to get this problem fixed as well. Maybe I haven't thought this through enough, but shouldn't a mufflerectomy help? Would this reduce backpressure enough, or does the flow of the exhaust through the turbo make this insignificant?

 

[Pelican18TQA4]

I've received a reply from Jeff and he is working on modifying a EGR valve to avoid it creeping open under high exhaust pressures. Of course, this would still leave it functional for emissions purposes. I certainly don't condone modifying the EGR to the point of it no longer functioning, but I made some block-off plates for mine and installed them today. I'm very happy to report that it seems my overboost issue has been eliminated!! Also, boost seems to develop slightly earlier leading to better torque off idle. Also noticed is that the strange bump in the hp/tq curve at around 2200-2400 RPM is gone. Again, I can't condone disabling the EGR for on-road purposes, but if you use your car off-road, I highly recommend this to alleviate overboost

Please note, this is applicable to modified PD100s only. Neither Jeff nor I claim that modifications like this will help overboost on anything but the PD100.

 

[hutchman]

Anyone with an A5 with RC1 or 2 experienced this problem. Just curious since I have one. My A4 doesn't have that problem

 

[TDikook]

That is freakin AWESOME! you guys rock for figuring this out. go figure, the ERG . and it seemed the alh guys had it right all along by removing them( for off road use only of course )
wow, gotta wait and see what Jeff figures out! and you are right, he is awesome, he worked on my car for over four hours trying to figure out why my car smokes so much, different maps, different ECUs, he tried everything, My Golf is just a smoker. but he went well past the extra mile to try and fix it.
Jeff in the man, by all means!!

Rock on Guys, Rock on

Eric B

 

[Pelican18TQA4]

That is freakin AWESOME! you guys rock for figuring this out. go figure, the ERG . and it seemed the alh guys had it right all along by removing them( for off road use only of course )
wow, gotta wait and see what Jeff figures out! and you are right, he is awesome, he worked on my car for over four hours trying to figure out why my car smokes so much, different maps, different ECUs, he tried everything, My Golf is just a smoker. but he went well past the extra mile to try and fix it.
Jeff in the man, by all means!!

Rock on Guys, Rock on

Eric B

Please don't give me credit for this. Jeff is the only one that figured out that the EGR is the probable culpirt here. I'm just confirming what he's indicating.

 

[TDikook]

pelican, you get credit too. you offering your car is an invaluable asset to solving this problem. Jeff can only do so much, he needs the hardware to work on to use that massive brain he has to solve the problems.

Just like the cruise control fix. he needs the cars it is affecting. he tried with mine as much as he could, but only got a little closer to the answer. so your part was a much needed help in solving this problem,

DONT SELL YOURSELF SHORT!!! all the small things add up

Thanks for contributing

Eric B

 

[Radman]

Pelican I also noticed that strange bump at aorund 2400 RPM's also. I guess simply unplugging the EGR connector would be a good test for that, maybe? However it will not stop the blowby that we think is causing the overboost.

 

[n1das]

I've received a reply from Jeff and he is working on modifying a EGR valve to avoid it creeping open under high exhaust pressures. Of course, this would still leave it functional for emissions purposes. I certainly don't condone modifying the EGR to the point of it no longer functioning, but I made some block-off plates for mine and installed them today. I'm very happy to report that it seems my overboost issue has been eliminated!! Also, boost seems to develop slightly earlier leading to better torque off idle. Also noticed is that the strange bump in the hp/tq curve at around 2200-2400 RPM is gone. Again, I can't condone disabling the EGR for on-road purposes, but if you use your car off-road, I highly recommend this to alleviate overboost

Please note, this is applicable to modified PD100s only. Neither Jeff nor I claim that modifications like this will help overboost on anything but the PD100.

I've been getting the same overboost condition on my 05 PD Jetta Wagen. It's chipped w/RC2 (at this past April's HO5G GTG in NH). The Wagen has stock clutch and intercooler but upgrades are planned for it...currently not high priority but will eventually happen. So far no clutch slip (yet) and I'm being kind to it while in the 1800-2400RPM range but still get on it at higher revs. The PD JWagen only has 15k miles on it and my 02 Golf w/228k miles is still my daily driver.

Upgrades to the PD JWagen aren't high priority right now but I'd like to get rid of the overboost condition. I've thought about going back to RC1+ but I decided I've already traveled too far down that slippery slope when it comes to mods.

I think I'll try making a plate as described to elminate the overboost. I'll leave the EGR valve totally alone.

The other thought I had was that if the EGR valve is creeping open during a hard run under load, the soot forced into the intake is probably contributing to intake clogging.

 

[Pelican18TQA4]

Uh oh, I've discovered a problem...I can't keep my right foot from being planted!! One thing I have noticed, the overboost issue is still there somewhat, but only at high RPM and I've only noticed it under full load. Hmm, perhaps the KP39 is still somewhat to blame.

 

[n1das]

Uh oh, I've discovered a problem...I can't keep my right foot from being planted!! One thing I have noticed, the overboost issue is still there somewhat, but only at high RPM and I've only noticed it under full load. Hmm, perhaps the KP39 is still somewhat to blame.

It might be the Intake Air Temp (IAT) creeping up and going out of spec, triggering the code and limp mode. I've gotten my limp modes more easily in the hot weather where heat soak is more of a problem.

Back in April when Jeff chipped my 05 PD Jetta Wagen w/RC2, he warned me that I'll need a clutch upgrade (no surprise there) and it *should* also have an intercooler upgrade. I'm planning to do an FMIC upgrade eventually.

I need to hook up VAG-COM and log some data to see what's going on with my PD JWagen. It hasn't been real high priority lately since it's not my daily driver.

 

[jjasperson]

Any new news?

I experienced an overboost problem the other night while attempting to see how fast my RC2 equipped '04 PD could go. I hit 115mph when it suddenly lost all power. I made it home but it was very disconcerting. Eric aka TDikook was helpful enough to lead me in the right direction.

So, is there a solution other than blocking off the EGR? I don't really think I'll have a problem with overboost as long as I'm not hitting jailable speeds, but I'd sure like to solve this problem none the less.

I didn't see a response to the question of the mufflerectomy reducing the back pressure enough to prevent the EGR blowby...any comments?

 

[Kabin]

I think Jeff has a good handle on this problem now. If I'm not mistaken the fix involved changing or tweaking an EGR flap spring.

 

[GoFaster]

Folks, I just deleted the pi$$ing contest which ensued right after this. Inflammatory off-topic comments are against the forum rules. Both of the people involved know who they are. KNOCK IT OFF. Both of you.

 

[G2D]

Folks, I just deleted the pi$$ing contest which ensued right after this. Inflammatory off-topic comments are against the forum rules. Both of the people involved know who they are. KNOCK IT OFF. Both of you.

My apologies to you and the Forum if my explanation of why I made my choice for a performance product was pissing and not explanation I intended it to be as to why it was best for me. I was sort of a third party invitee but your point has been made to this third party.

 

[2footbraker]

So is switching out some EGR spring standard issue for RC'ed PD's now?

 

[TDikook]

I dont think that is the problem. if you look at the EGR valve itself. the valve opens INTO the exhaust side. I cleaned out my EGR and I noticed that around the so called sealing surface from the intake side to the exhaust side( there isnt a real surface) they were black, where I believe the leaking could be from. if that is the case (which is what I believe) bocking off the EGR contact with the intake side may be the only way. thank God I am Chipped. I am saving up for the delete kit now.
here is the pic of the EGR valve. notice on the bottom left where the black is. I couldn't get it off no matter how much I scrubbed. this is where I believe the leak is from. on top notice the spring pushes up. that keeps the valve shut.
http://pics.tdiclub.com/showphoto.php?photo=31102

Eric B

 

[jjasperson]

I dont think that is the problem. if you look at the EGR valve itself. the valve opens INTO the exhaust side. I cleaned out my EGR and I noticed that around the so called sealing surface from the intake side to the exhaust side( there isnt a real surface) they were black, where I believe the leaking could be from. if that is the case (which is what I believe) bocking off the EGR contact with the intake side may be the only way. thank God I am Chipped. I am saving up for the delete kit now.
here is the pic of the EGR valve. notice on the bottom left where the black is. I couldn't get it off no matter how much I scrubbed. this is where I believe the leak is from. on top notice the spring pushes up. that keeps the valve shut.
http://pics.tdiclub.com/showphoto.php?photo=31102

Eric B

That's great info Eric...it looks like the culprit has been located!

You mention a delete kit...where might I purchase this kit and what exactly is it called? (EGR delete kit, etc.)

Thanks for your diligence!

 

[DrSmile]

My 05 RC1 PD wagon (no other performance mods) also overboosts over 100mph when floored, it certainly has nothing to do with the VNT being stuck...

Has anyone tried running a straight through, larger exhaust? With other cars I've had, exhaust restrictions did lead to boost creep. Boost creep is a well known problem in turbocharged cars and I'd expect this to be the cause of the overboost.

 

[TDikook]

Hey Dr. that isn't it. there is a member that has a bigger exhaust and he still had creep. this thread:
http://forums.tdiclub.com/showthread.php?t=128602

it will shed some light on what is going on, and the stuff that has been tried to correct it. I still think Jeff has it when he mentioned leak by the EGR valve. it makes a lot of sense.

Eric B