2012 Touareg TDI - Very rough idle and odd deviations

[Dr Sheldon]

Rule of thumb is that Compressions should be within 10% of each other. 10% being the Limit not the Norm !!

so 400 psi - 10% = 360 Psi

Compressions finally done... On a cold engine since that's where the issue lies.
1 - 350
2 - 400
3 - 390
4 - 350
5 - 350
6 - 380

I saw in the manual that the max difference is 5

5 WHAT !! And why are you assuming 5 Bar ??

I would suggest 5% is a much better assumption - and compressions within 5% of each other will contribute to a smooth running engine !!

 

[Dr Sheldon]

Compressions finally done... On a cold engine since that's where the issue lies.

Wrong !! A very common misconception there that needs to be nipped in the bud !!

Your misfire is at idle - Correct ?
Idle is ~800rpm - Correct ?

You are doing a compression test at Cranking speed ~300 rpm with no load on the Engine - Correct ?

Do you have a misfire at 300rpm ?? Clearly you do not so your test method is somewhat flawed ? Correct ?

Do a Dynamic Compression test for more accurate results !!

Ideally 2 Pressure transducers - One in Inlet and the Other in the Exhaust measuring pulses with a scope is the correct and proper, belt and braces, test for this symptom.

 

[andrePNW]

5 WHAT !! And why are you assuming 5 Bar ??

I would suggest 5% is a much better assumption - and compressions within 5% of each other will contribute to a smooth running engine !!

Just my assumption, wouldn't have to assume if the documentation stated otherwise. :P

Wrong !! A very common misconception there that needs to be nipped in the bud !!

Your misfire is at idle - Correct ?
Idle is ~800rpm - Correct ?

You are doing a compression test at Cranking speed ~300 rpm with no load on the Engine - Correct ?

Do you have a misfire at 300rpm ?? Clearly you do not so your test method is somewhat flawed ? Correct ?

Do a Dynamic Compression test for more accurate results !!

Ideally 2 Pressure transducers - One in Inlet and the Other in the Exhaust measuring pulses with a scope is the correct and proper, belt and braces, test for this symptom.

Fair point, although I wouldn't say fully flawed if it's already revealing a difference outside said tolerated range. Correct?

EDIT: As for transducers, unfortunately that's something I don't have nor do I have the audacity to trust the shops around me anymore... Sadly..

 

[SaVAGeSoot]

Compressions finally done... On a cold engine since that's where the issue lies.
1 - 350
2 - 400
3 - 390
4 - 350
5 - 350
6 - 380

I saw in the manual that the max difference is 5.. Just 5... which i'm assuming means 5 bar? So based where i live it's 5x30? = 150 max psi difference. That seems wildly large but..

Any grand ideas?

Weird that the manual just gives you values without a UOM..... what manual are you looking at?

 

[SaVAGeSoot]

I don't know what @Dr Sheldon is going on about this morning, but he's overcomplicating stuff when there's no need for it.....
Let's dumb it down a little....
There's no need for any assumptions. It's NOT %, it's not Pesos, it's not PSI.... the manual clearly tells us what the UOM is.

Up above, your #5 GP pressure sensor was saying you have no compression.
You've now confirmed that you DO have compression there.
So, could it be the GP is faulty and not reading a value? Could this be why I suggested earlier that you take the GP from the cylinder that IS reading and swap it over?

Inquiring minds want to know!

 

[SaVAGeSoot]

@andrePNW
You've previously mentioned that you swapped injector from #2 to another cylinder, but the "out of whack" deviation did not follow the injector.
Were injector learnt values reset after this swap? How long did you run\drive the vehicle with the injectors swapped into other pots?
I'd expect the ECU would need to run the engine for a while to re-adjust\compensate for the different delivery parameters if injector #2 had an issue, etc.
As such, I don't believe you'd see the deviations reflect the physical swap immediately.... but I'm just theorizing over here.

 

[andrePNW]

I don't know what @Dr Sheldon is going on about this morning, but he's overcomplicating stuff when there's no need for it.....
Let's dumb it down a little....
There's no need for any assumptions. It's NOT %, it's not Pesos, it's not PSI.... the manual clearly tells us what the UOM is.

Up above, your #5 GP pressure sensor was saying you have no compression.
You've now confirmed that you DO have compression there.
So, could it be the GP is faulty and not reading a value? Could this be why I suggested earlier that you take the GP from the cylinder that IS reading and swap it over?

Inquiring minds want to know!

Thank you... I didn't feel like calling him out last night

Turns out across other CATA's I've requested this same information with the same result... Seems GP 5's data can't be seen? Same was the case for a legitimate vw dealer/shop with there proprietary tool. So I've jumped off #5 being an issue, and it was swapped with no change. Anything on #5's lead refuses to state any data (voltages match #2's lead, and resistances are in spec of manual) you'd expect from the sensor. (Seemingly not unique to just my treg at this time thus far)

Weird that the manual just gives you values without a UOM..... what manual are you looking at?

The latest and greatest from erwin.

@andrePNW
You've previously mentioned that you swapped injector from #2 to another cylinder, but the "out of whack" deviation did not follow the injector.
Were injector learnt values reset after this swap? How long did you run\drive the vehicle with the injectors swapped into other pots?
I'd expect the ECU would need to run the engine for a while to re-adjust\compensate for the different delivery parameters if injector #2 had an issue, etc.
As such, I don't believe you'd see the deviations reflect the physical swap immediately.... but I'm just theorizing over here.

Adaption valves were reset yes, as for how long it was driven I'd say 500+ mi. Until I took the rig into a shop that ended up swapping 1,2 -> 4,5 to troubleshoot the same issue. They claimed a full replacement of all the injectors but I call BS/scape goat solution until it's actually proven/warranted.

 

[SaVAGeSoot]

So are you saying that injector compensation values did NOT change to follow any of the swapped injectors?
The suspect value (issue) is always constant to #2 cylinder, regardless of which injector is swapped into that cylinder?

 

[SaVAGeSoot]

Turns out across other CATA's I've requested this same information with the same result... Seems GP 5's data can't be seen? Same was the case for a legitimate vw dealer/shop with there proprietary tool. So I've jumped off #5 being an issue, and it was swapped with no change. Anything on #5's lead refuses to state any data (voltages match #2's lead, and resistances are in spec of manual) you'd expect from the sensor. (Seemingly not unique to just my treg at this time thus far)

I actually do recall reading something similar somewhere.... so it is entirely possible that whatever reading #5 takes on the CATAs, only gets reported to the ECU or some other module that makes use of this metric..... it would appear that the ECU simply doesn't "regurgitate" this info out to the rest of us.... must be a "need to know basis" only....

My next suggestion would be to check injector return rates while engine is running.

 

[andrePNW]

So are you saying that injector compensation values did NOT change to follow any of the swapped injectors?
The suspect value (issue) is always constant to #2 cylinder, regardless of which injector is swapped into that cylinder?

The deviation value whatever that value may be... will always be isolated to #2 at this rate, cause that's the only data provided. Whether that it's issue prone or not... If the glow plug wire was longer i'd pop it into other nearby cylinders for comparison at runtime but that's not an option without splicing, and no chance in hell that's happening.

I actually do recall reading something similar somewhere.... so it is entirely possible that whatever reading #5 takes on the CATAs, only gets reported to the ECU or some other module that makes use of this metric..... it would appear that the ECU simply doesn't "regurgitate" this info out to the rest of us.... must be a "need to know basis" only....

My next suggestion would be to check injector return rates while engine is running.

Glad someone finally acknowledged that... As for return rate most of the kits i've seen don't clip on to the return outlet, might just have to throw something together unless someone has any ideas otherthan the VAG tool...

Otherwise, there's a highly rated diesel injector shop a few hours away that'd be willing to flow test/ultrasonic clean/etc if it comes to that point, but considering IQ values aren't mental I don't see the value in doing that... yet?

 

[SaVAGeSoot]

You didn't answer #28!
What did your intake valves look like when you did your manifolds? At your mileage, they could be quite full of carbon buildup, which might explain the lower reading on half your cylinders.
There are cheaper flow meter tools out there... check ebay\amazon\chinesium sources..... or go pay a dealer to test the return flow... I can't imagine it would cost more than an injector!

If it was me, I'd probably throw ONE injector at it... once I answered all the questions that have been asked.

 

[SaVAGeSoot]

Wait a second.... how did the injector seals\seats look?
When you "swapped" injectors, did you just reuse old seals\hold down bolts? (you probably have seal\seat leaks if so)

 

[andrePNW]

You didn't answer #28!
What did your intake valves look like when you did your manifolds? At your mileage, they could be quite full of carbon buildup, which might explain the lower reading on half your cylinders.
There are cheaper flow meter tools out there... check ebay\amazon\chinesium sources..... or go pay a dealer to test the return flow... I can't imagine it would cost more than an injector!

If it was me, I'd probably throw ONE injector at it... once I answered all the questions that have been asked.

Sorry.. I forgot that post got yeeted with the thread split. Slight increase of 0.04 at warm idle so nothing crazy. As for injector shop, full test + clean/etc is $75 per injector.

Valves don't look.. awful? I've seen way worse across the web. Other valve pictures aren't uploading for some reason.

Wait a second.... how did the injector seals\seats look?
When you "swapped" injectors, did you just reuse old seals\hold down bolts? (you probably have seal\seat leaks if so)

Replaced everything... copper seals, mid shaft o-ring, and return outlet o-ring. Seals were intact but replaced either way, no pictures sadly. The nuts were reused but the tensioning plates weren't.

 

[SaVAGeSoot]

Do the valves on #2 look worse than the rest? Assuming that you can identify them?

 

[SaVAGeSoot]

Replaced everything... copper seals, mid shaft o-ring, and return outlet o-ring.

Did you "recut" and\or clean the seats in the heads?

 

[andrePNW]

Do the valves on #2 look worse than the rest? Assuming that you can identify them?

Didn't look worse in comparison, I'll get another set of pictures and provide them with identification tonight.

Did you "recut" and\or clean the seats in the heads?

Vaccumed some debris off the seats, otherwise they were clean as a whistle afterwards. Don't have the tool to cut/scrape the seat at this time.

 

[SaVAGeSoot]

Did you ensure to install all copper seals in the correct orientation?
Any chance you flipped #2 around?

 

[andrePNW]

Did you ensure to install all copper seals in the correct orientation?
Any chance you flipped #2 around?

If the beveled end is meant to be facing the injector base, then yes orientation is correct.

 

[Dr Sheldon]

Just my assumption, wouldn't have to assume if the documentation stated otherwise. :P

YOUR Assumption and YOUR Choice / Source of documentation.

If that was the best documentation I could get - I would point blank refuse the Client and the Car !!

No end of broken cars within a 5 mile radius where I can have reliable Technical Data.

Fair point, although I wouldn't say fully flawed if it's already revealing a difference outside said tolerated range. Correct?

Not Fully Flawed = Flawed !! The electronics in your car are in Binary - 0 or 1 - Yes or No !! That is it !! No wiggle room regardless of how eloquently you scribe here in the VCDS Forum

EDIT: As for transducers, unfortunately that's something I don't have nor do I have the audacity to trust the shops around me anymore... Sadly..

Yes - the transducers, the Scope, the training to use and make sense of the results is a $10k plus investment !! Not economically viable for yourself.

I have and use that stuff on a daily basis - But that is what I do , I get paid because I have all of that !!

I will say if that you did see that way of working you would think again - The accuracy is an eye opener !! Does put Franchised Dealer methods to shame !!


I see you have dismissed any idea of doing a Dynamic Compression test ?!

 

[andrePNW]

YOUR Assumption and YOUR Choice / Source of documentation.

If that was the best documentation I could get - I would point blank refuse the Client and the Car !!

Feel free to point me to another source that isn't the most recommended option ALL OVER this forum. I'll wait...

I never stated I wasn't going to do a dynamic compression test. I'm just continuing conversation whilst i'm at work with the information I have available to me.