BEW overboost and surge issue. Help & advice needed..!

PD Golf

Member
Joined
Nov 23, 2009
Location
Columbus, OH
TDI
2005 VW Golf
I want to preface this by saying that I am not blaming anyone for my car's issues. Jeff Robertson (of Rocketchip) and Jon Hamilton (of Jon's Automotive) were more than helpful and very generous with there time trying to resolve this issue. The only reason for mentioning their names is so readers can know the caliber of the experts helping me with this issue(s). They identified the fuel contamination issue, weak lift pump and the bad MAF. These were all apparent problems that needed to be (and since have been) resolved. They were limited to trying to diag a car with obvious issues that could not be resolved at that particular time and therefore ran into a dead end for further diagnostics. I'm only posting this info to brainstorm for possible diag tips and/or solutions...

Here is what I had just before any recent changes were made: 2005 Golf (PD, BEW), thru exhaust, egr delete, new VNT 17, RC1+, 2.5 bar map. Car ran great, smooth power, no surging, no over boosting, ran at a max of 17-18 psi, egt's were happy (and still are).

What was changed: Went from a RC1+ to a RC2 w/ a 3 bar map. Due to a 30psi spike after the RC2 and 3 bar map was added, we had the actuator adjusted to the recommended spec 4-5" to 17-18" of vacum range as it was out of adjustment (although there was no lag or spike with the VNT17, RC1+ and 2.5 bar map). The N75 valve was swapped back/forth with another to eliminate this as an issue- existing one seems ok. Vacum lines were checked for correct connection and vacum system holds good vacum (no leaks). The MAF was unplugged to eliminate this as the issue. The lift pump was replaced as it's pressure was low and it could almost not be heard when cycling the key. (with an ear next to the pump)

Other discovered issues: Per the PO001 code the car has thrown in the past and per Jeff's VagCom logs, the MAF was known to be bad. The MAF was replaced. The car also had contaminated fuel. There was gasoline in the diesel. Of course, the tank was drained and the good fuel was added.

The result: Car spikes upwards of 30 psi. The boost surges bad. It seesaws back and forth from 25-30 at WOT. At times, the boost will even suddenly peg the gauge at 35 psi for a split second. With the cruse set a 70mph, the car runs at 20 psi. Seemed unusual at a very low load on almost flat road. The car is even making massive amounts of boost (20-25+ psi) at as little as 1/4 throttle while driving like a grandma at speed as little as 30-40 mph... I swear the boost gauge moves almost like the tach while driving the car nice and easy. Once you get to the desired speed and begin to maintain that speed, it seems that the boost is all or nothing and it kicks back and forth. With the slightest touch of the throttle, the boost will go from 0 to 15+ psi (up to 30 ish) depending on how much more throttle you demand. Like an on/off switch.

This is the only self diag I have done myself- to confirm that it was not an actuator or turbo vane issue, I checked the vacum going to the actuator by placing a vacum gauge with a tee fitting inline with the vacum line that goes from the N75 to the turbo. The vacum fluctuates with the boost. So, it does not appear that anything is sticking with the actuator or turbo vanes (new turbo) and instead it is being demanded.

If anyone has any knowledgeable info please share. I would like to continue to attempt to resolve this issue.
 
Last edited:

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
I've been through mostly the same thing (just no bad MAF or contaminated fuel). RC3 though. Still have 2.5bar MAP (have a 3bar for the next time I meet up with Jeff). Also separated the (new) N75 vent from the airbox.

I over adjusted the actuator (intentionally) and I make almost no boost cruising at 70. 1st through 3rd would peg the gauge until I added a boost valve. Only issue now is that the amount of low throttle cruising I do will make the VNT stick until I do a good WOT run in 4th, which I can't do often..

No surging for me though, just overboosting.

I have a PD150 intake sitting in the garage and I'm going to see if that helps in any way - hoping that the stock one with the flappers (disabled) is a bit restrictive since I do blow black smoke at 30+psi.
 

OmegaRenegade

Vendor
Joined
Dec 15, 2005
Location
Brampton
TDI
2004 Jetta
i'm thinking this could be bad MAP sensor - everything else seems to have been covered. when the boost is "seesaw'ing" as you put it, is this reflected in your vag-com logs? An incorrect reading from the MAP sensor will cause your ECU to do funny things with your boost.
 

brum

Veteran Member
Joined
Nov 30, 2009
Location
Bulgaria
TDI
Passat B5, 1.9 TDI, AFN
I also vote for bad MAP. Or bad software mod for the 3 bar MAP. Check what VAG-COM says on channel 11 and they are close to the one from the boost gauge.
 

PD Golf

Member
Joined
Nov 23, 2009
Location
Columbus, OH
TDI
2005 VW Golf
Was the VNT-17 new? Does it have the smart actuator?
New VNT17 with a new smart actuator from IDparts.com

I've been through mostly the same thing (just no bad MAF or contaminated fuel). RC3 though. Still have 2.5bar MAP (have a 3bar for the next time I meet up with Jeff). Also separated the (new) N75 vent from the airbox.

I over adjusted the actuator (intentionally) and I make almost no boost cruising at 70. 1st through 3rd would peg the gauge until I added a boost valve. Only issue now is that the amount of low throttle cruising I do will make the VNT stick until I do a good WOT run in 4th, which I can't do often..

No surging for me though, just overboosting.

I have a PD150 intake sitting in the garage and I'm going to see if that helps in any way - hoping that the stock one with the flappers (disabled) is a bit restrictive since I do blow black smoke at 30+psi.
I was thinking of playing with the acutator to see if this has any effect on this issue, keeping in mind that the car ran great when it was out of adjustment- but this doesn't really make a whole lot of sense. I suppose I resort to this- worse case.

i'm thinking this could be bad MAP sensor - everything else seems to have been covered. when the boost is "seesaw'ing" as you put it, is this reflected in your vag-com logs? An incorrect reading from the MAP sensor will cause your ECU to do funny things with your boost.
I'm not certain if the seesaw surging issue is recognized by the vag-com. I do not have vag-com myself, but of course Jon and Jeff do. If you're trying to eliminate that it is a false boost gauge reading this is not the case as you can hear the exhaust tone change pitch when this is occurring. So the seesaw'ing surge issue is actual. (New South is certainly not the best gauge out there) The gauge reads about 2 psi higher than the vag-com and i'm certain that it is exaggerating the boost spikes a little.
 

OmegaRenegade

Vendor
Joined
Dec 15, 2005
Location
Brampton
TDI
2004 Jetta
I'm not certain if the seesaw surging issue is recognized by the vag-com. I do not have vag-com myself, but of course Jon and Jeff do. If you're trying to eliminate that it is a false boost gauge reading this is not the case as you can hear the exhaust tone change pitch when this is occurring. So the seesaw'ing surge issue is actual. (New South is certainly not the best gauge out there) The gauge reads about 2 psi higher than the vag-com and i'm certain that it is exaggerating the boost spikes a little.
i was merley asking not to put doubt in the boost gauge but to challenge the MAP sensor itself. If the readings are all over the place then the ecu will be playing with the N75 pulsing to apply/remove vacuum to the VNT actuator causing the issue you see.
 

PD Golf

Member
Joined
Nov 23, 2009
Location
Columbus, OH
TDI
2005 VW Golf
i was merley asking not to put doubt in the boost gauge but to challenge the MAP sensor itself. If the readings are all over the place then the ecu will be playing with the N75 pulsing to apply/remove vacuum to the VNT actuator causing the issue you see.
I see... I that makes sense. Would a vag-com answer this? I'm considering going back to the 2.5 bar MAP and RC1+. Or, even a stock tune if I absolutly have to.

It's gotta be something we changed that day.
 

dieselpower04

Veteran Member
Joined
Jun 26, 2007
Location
Outside Tampa, FL
TDI
2004 Golf GLS TDI (sold)
You dont have the boost gauge running off the MAP sensor do you? There has been issues with that. I would either run the car with VAGCOM to see if the MAP pressure requested vs actual is totally messed up.

You should see something like this when its right on the money:


Hope this helps
 

PD Golf

Member
Joined
Nov 23, 2009
Location
Columbus, OH
TDI
2005 VW Golf
You dont have the boost gauge running off the MAP sensor do you? There has been issues with that. I would either run the car with VAGCOM to see if the MAP pressure requested vs actual is totally messed up.

You should see something like this when its right on the money:


Hope this helps
The boost gauge is tapped into the upper IC pipe. It's a mechanical gauge. I'll have to get with someone who has a VagCom and check into this...

I'm still in the process from getting my old 2.5 bar MAP back from Jeff. (I gave it to him when he installed the 3 bar, thinking that I would never need it again. I have not been able to get him to return a voicemail and/or e-mail. I'm begining to think that I should just go buy another one.

Thanks for the advice and help!
 

jsrmonster

Veteran Member - TDIClub Enthusiast
Joined
Apr 22, 2002
Location
Red Lion, PA
TDI
15 Golf SW DSG, RC3 piped, 99.5 Jetta Rocket PD150 6spd 4motion, 2000 ASV110 RC6 "Silverbullet" 5spd Race Car, 2003.5 Cummins QCLB 4x4 "Blue Monster" Jeep CRD juiced, MB Sprinter van juiced up
Hi Mike - I came to the conclusion that your injector return (lazer'd) holes inside the unit injectors are clogged from running veggie or B100. I paid for your new lift pump thinking that was it and it made no difference plugged in or unplugged. This tells me it's not fuel delivery! You have maf delete tune and made no difference plugged in or unplugged (values = 90% good). You can also measure the fuel rail pressure like I discussed and should see 50-100psi just wacking the throttle while idling. I would bet you the pressure here is good, cuz when these fail, the car gives hard starting, and yours always fires up 1st crank. http://www.youtube.com/watch?v=-FHfTOrWS88

Did you check your camshaft for excessive wear like I suggested? Did you install the clear glass fuel filter (mr gasket) on the return line to see if carbon is entering fuel rail thru injector seals or cracked head? Your fuel pump (and filter) was heavily blackened with soot or some kind of crap!

I have seen this on several cars over the years where the injectors are plugged up and won't return fuel. There are thousand of very very tiny lazer'd holes, (smaller than your eye can see) that fuel returns thur and when these get coked up and clogged with crap, the car becomes very weak cuz it cannot circulate fuel effeciently. Your car can run ok with oem or stage1, but stage 2 is asking too much and drivers request is not being met with fuel and air flow is limited, so boost is being requested to make up for the volumetric flow that lacks from missing fuel.

Get some new injectors to install and call me if you need help. I will pay for your injectors ($500 plus old ones returned) if it is not the culprit!

No problem returning your old map sensor, but you're barking up the wrong tree, imho.

I will see if I can find a magnified pic of these micro-sized PD injector-body return return holes. This is a good lesson for those who don't listen and run BioD or veggie in PD cars. I guess you can mod the return holes to pass larger particles (by edm). I feel sorry for guys with CR's doing this now too! It gets very expensive even with older rotary pump TDI's!

Jeff

http://www.seatcupra.net/forums/showpost.php?p=3049491&postcount=332
 
Last edited:

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
will pay for your injectors ($500 plus old ones returned) if it is not the culprit!
Wow, Jeff, props to you for standing behind your work. There are VERY few people out there that would do that. Most of the time its throw parts at it at the costumer's dime. I'm impressed to say the least....
 

Farfromovin

Torque Addict
Joined
Apr 9, 2005
Location
Ventura, CA
TDI
03 Golf 2dr- PD150 6m
Pff, I was about to give advice and then find Jeff in here offering money back if he's not right.

OP- I'd take your tuner up on that offer!
 

PoochiePD

Veteran Member
Joined
Mar 23, 2005
Location
Sun Prairie, WI
TDI
2013 Tempest Blue Jetta
Did anything ever come of this? Did you ever confirm the problem? (and solution?)

Someone with a similar problem is just curious...
 

JetDoctor1

Member
Joined
Aug 23, 2007
Location
Atlanta
TDI
04 Jetta TDI GLS
I was going thru the same thing on my 04 pd. Changed the cam out did the frank06 grouved bearings and oil mod. now boost goes up to 20 and settles at 18. I think the cam followers are overheating boiling the oil inside holding the intake valve slightly open releasing pressure back into the intake and now you see a overboost.
 
Top