VW 1.8T Cut-off Valve DTC Code P0507 & P1136 (pic)

[Bluestream]

I am trying to trouble shoot some DTC codes on my VW.
Codes are:

P1136 Long term fuel trim, idling, bank 1 - system too lean
P0507 Idle control System RPM high.

I am basically looking for a intake leak of some kind. I have applied vacuum to the Cut-off valve and it does not hold vacuum. This valve is installed in the air intake to the Turbo. (you can see the valve if you follow the hose off my vac guage) Should this be able to hold vacuum?

 

[The Critic]

Tbh, ask the guys on vwvortex. They are probably more familiar with this kind of car.

 

[mechtech2]

Gosh...I want to say it should hold vacuum, but I've seen valves operating correctly that seemed to NOT hold vacuum. It depends on the design.

Like critic said, go website specific.

In general, you can have the car idling and spray a bit of carb cleaner here and there to check for leaks. An unlit propane tank will do the same. [the engine should change and probably raise a bit momentarily]

 

[Thermo1223]

Actually it is a diverter valve.

If it is just that they are prone to failure and should hold a vacuum. Even if you are not increasing engine power an aftermarket unit is better in everyway(metal for one).

Hook on with someone who has a Vag-com and you will know for sure. VW/Audi's really can't be read properly with a run of the mill OBDII scanner.

At face value that's all that seems to be wrong if the valve is leaking which would cause a higher idle and an off reading to the MAF. It's job is to recirculate air when the throttle plate is closed or else it would fight against the compressor. It is not good for longevity if it does that. It basically sends high pressure air to a low pressure area when the throttle is closed abruptly(like shifting/WOT let off).

http://www.vagfans.com/forum/viewtopic.php?f=4&t=88

ECS Tuning's site is down or else I'd show you a new one.

 

[Thermo1223]

http://www.ecstuning.com/Volkswagen-Golf_IV--1.8T/Engine/Intake/ES581/

Better higher HP rated OEM ver. for stock replacement.

http://www.ecstuning.com/Volkswagen-Golf_IV--1.8T/Engine/Intake/ES1832052/

Buy this and never worry again, uses a piston and spring.

 

[Bluestream]

Thanks,

Yes, the street name is diverter valve, and it seems to be a common issue with use and time. I found this procedure for testing without a vacuum gauge:

http://www.vaglinks.com/Docs/Misc/VAGLinks.com_DIY_Testing_a_Bosch_Diverter_Valve.pdf

I have not removed the old valve, but have ordered a new one from the Stealer for $61. It is supposed to be an improved design, so we shall see. I don't have the VAG-COM so have to make due with my code reader. I will report back after I get installed on Friday in case someone else reads this post at a later time. I am convinced this part is causing my codes

Thermo1223, what kind of damage would be done if this was not fixed? Car came this way when I bought it 2000K miles ago. Previous owner was not much on keeping things fixed...

 

[Thermo1223]

Imagine what 2 table top fans sound like pointed at each other. In open air it would be harmless, the added stress wouldn't cause mechanical fatigue because the air pressure has a place to go.

Now imagine them blowing into the same tube sealed so only the air can go into the tube not out. One fan on, no problem the other spins freely but then power on the second fan and watch it struggle. Now imagine varying power going from low to high. You can bet those motors wouldn't last long.

The same can be applied to an engine, it is a closed system.

Throttle plate open, turbo spooling making boost/psi, then closed is the throttle plate. The air slams into the plate and and a pressure wave heads for the compressor. You can hear the buffeting noise easily. The turbo wasn't made for the pressure to be exerted that way and eventually it can cause it to fail. That valve opens on vacuum sending the pressure to inlet of the turbo, around the compressor to be harmlessly recycled.

A pressure washer does it very similar when idling.

If it is constantly recirculating and failed in that manner well I doubt any long term effects would be evident although you could be overworking the turbo. You would basically get lower fuel economy and lower performance because you are not achieving the desired pressure. The ECU probably cuts timing & fuel to compensate.

Sorry if it is confusing, I understand it but I may not be the best teacher.

 

[Bluestream]

Thanks, I think I get it.

I wish I had looked into this sooner, but 2000 miles hopfully did no damage. Not sure how the the PO had the problem. Part comes in tommorow, and I am going to install it right away. Will cut open the old one for a look see.

 

[Thermo1223]

Ya it won't cause any immediate damage but can add to the bearing/shaft stress overtime(like close to 50k miles).

Odds are the rubber diaphragm just tore like it did in my TDI's actuator(big metal can attached to the turbo) which is responsible for closing/opening the wastegate in your application.

TDI's used variable vane guides so I would get no boost at all...driving a TDI like that is SLOW haha.

 

[javacontour]

Originally Posted By: Bluestream

Thermo1223, what kind of damage would be done if this was not fixed? Car came this way when I bought it 2000K miles ago. Previous owner was not much on keeping things fixed...


If you got 2000K miles, then I'd say you got your money's worth, LOL

 

[Bluestream]

I picked up the new diverter valve today, and as I suspected it holds a vacuum. After install, car runs smother, and seems to have more power. Codes are gone for now..(knock on wood)

 

[CBR.worm]

If the problem comes back, I would recommend checking or changing all the check valves in the PCV system and most likely many of the hoses/pipes. We had this engine in an '04 A4 (for some reason the longitudinaly mounted versions were more troublesome) and by 40K miles the hoses would crack or collapse if you applied a little pressure. What started out as a faulty diverter valve replacement ended up as a full scale PCV system and vacuum hose/jet pump/check valve replacement.

 

[Bluestream]

Well my code did came back today..

Not sure where to start, but the PVC valve is as good as any. All the vac lines seem good or have been replaced. I wonder if an lazy front O2 sensor would cause a lean code? (I have replaced the rear O2)

 

[The_Eric]

Originally Posted By: Bluestream
I wonder if an lazy front O2 sensor would cause a lean code? (I have replaced the rear O2)


I'm pretty sure it could.