Misfire/Hesitation During Warmup

[Jimbo160]

Hi all,
First post here, and, glad to see there’s a proper forum for these vehicles rather than just a facebook page.

Ok, so, I bought a 2016 66 plate Transporter, recently. It’s a 2.0TDI (150) with a CXHA engine. It’s on 85k miles.
It starts and runs fine with a cold or hot engine but very soon after buying it I noticed that if the vehicle has been driven then left for a short while (maybe 15-30 mins) and the engine is warm but not up to normal operating temperature. There is a misfire/hesitation under partial throttle. As in when accelerating normally. This can be noticed while accelerating as gradually as possible, also. If the accelerator is pressed more than a quarter the way down it seems to disappear. And, once up to 90°C coolant temperature the problem goes away.
While it’s doing this, the idle is slightly lumpy, as well.
If has me pretty concerned as it’s not just slight. It feels like a full loss of power for a split second.

Any help or suggestions are much appreciated

 

[Pauly]

Have you got anything diagnostic that can fault scan it just to see if anything is logged ?

Starting of with the basics, are you sure it’s not doing a dpf regen ? You could be stuck in a loop of incomplete regens if your only doing short trips

 

[Jimbo160]

I don’t have any diagnostics tools, unfortunately. I should’ve mentioned, there are no lights on the dash. I gather this doesn’t mean there are no codes logged?

Is there a cheap diagnostic tool that’s worth buying?

I can’t be certain it’s not doing a regen. But, I recently did a 2hr motorway journey in it and it had been misfiring beforehand and also since. I’d have thought that’d have given it enough time to do a regen?

 

[Pauly]

That would be enough to complete a regen cycle
I think as it’s technically starting ok and working ok you are going to struggle to diagnose it without some half decent diagnostic/logging kit, VCDS lead/software would be good in this situation to log engine parameters while driving but you are looking £200-300 assuming you already have a laptop

 

[Pauly]

@mmi

 

[Jimbo160]

That would be enough to complete a regen cycle
I think as it’s technically starting ok and working ok you are going to struggle to diagnose it without some half decent diagnostic/logging kit, VCDS lead/software would be good in this situation to log engine parameters while driving but you are looking £200-300 assuming you already have a laptop

Thanks Pauly!
If I was to get VCDS what parameters would I be looking to keep an eye on?

 

[Pauly]

That’s not my dept, let’s hope @mmi responds as he’s the master on engine diagnostics
If you want to do some reading have a look at some of his posts and you will get the idea

 

[mmi]

If I was to get VCDS what parameters would I be looking to keep an eye on?

If you want to do some reading have a look at some of his posts and you will get the idea

As a starting point some good setups below

204 DSG intermittent momentary power loss

I'm not sure. I'll do similar runs with mine (same CXEB engine) to get more data. A 30 minute capture today didn't have any of the drop-outs with these - but I didn't push it that much. IDE07785 Turbine actuator 1 bank 1: posit.feedback - Actual value IDE07793 Turboc.1 turbin.bypass valve 1 B...

www.t6forum.com

204 DSG intermittent momentary power loss

Hi all, Desperately looking for some assistance! I have a 2018 204 DSG high line. Had it from 8k miles, now has 82k on the clock. I’ve done all of the servicing and maintenance on it as I’m very mechanically minded and my business is automotive electrical design. However, I have a fault that I...

www.t6forum.com

Lumpy engine start and idle

lets see what plots @mmi can pull from the data.....:mexican wave:

www.t6forum.com

Spoiler: Engine build-in diagnostics tests

Also quite a few engine build-in diagnostics tests that can be run for further analysis by VCDS - extremely powerful diagnostics tool.

[T6_measured] 01-Engine - Built-in test for EGR

So it seems - inevitable P0401. Well, visited a VW garage to be tested - the van had accumulated 30 events in ECU's memory since July 2021 (since 20 months now). Eventually managed turn on the emission light at event number 31 - thus had a priviledge to have EGR flow tested. The result -...

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EGR Valve Self Test Procedure (IDE00242)- P046C?

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi...

www.t6forum.com

[T6_measured] 01-Engine - Built-in tests for turbocharger

01-Engine - Basic Settings IDE00457-Test of turbocharger HOW-TO run engine's built-in test for turbocharger Engine running VCDS > Select > Engine > Basic Settings > IDE00457-Test of turbocharger Select "Measuring Values" Pick up e.g. the following data items for monitoring: IDE00021 Engine...

www.t6forum.com

[T6_measured] 01-Engine - Built-in test for Transfer fuel pump

A quick DIY way to test fuel lift pump's basic functionality. The test takes advantage of engine's fuel high pressure sensor (in fuel rail). Running the lift pump continuosly makes the pressure eventually "leak" through high pressure pump and can be detected by fuel pressure sensor. As a side...

www.t6forum.com

Anyways, more than happy to help to try to analyse data files

---

Ok, so, I bought a 2016 66 plate Transporter, recently. It’s a 2.0TDI (150) with a CXHA engine. It’s on 85k miles.

Service history? Has the fuel filter has been replaced - although not the prime suspect for the symptoms?

 

[Jimbo160]

Service history? Has the fuel filter has been replaced - although not the prime suspect for the symptoms?

Thanks mmi. A lot to get my head around but I’ll do some reading. Looking at those plots baffles me at the moment. I’m more used to working on things with carburettors

As for service history…the van has some, but it’s broken and vague. Probably the main reason it was cheap. It’s just had a service but that was only oil and filter. There is a chance that it’s still on the original fuel filter as there’s no record of it being done. But, like you say, it’s not normally the cause of this issue. I’d imagine full throttle would cause any issue relating to a clogged fuel filter to show up rather than low engine rpms and light throttle.

Are there any physical tests I can carry out on the EGR?

 

[Jimbo160]

As a starting point some good setups below

204 DSG intermittent momentary power loss

I'm not sure. I'll do similar runs with mine (same CXEB engine) to get more data. A 30 minute capture today didn't have any of the drop-outs with these - but I didn't push it that much. IDE07785 Turbine actuator 1 bank 1: posit.feedback - Actual value IDE07793 Turboc.1 turbin.bypass valve 1 B...

www.t6forum.com

204 DSG intermittent momentary power loss

Hi all, Desperately looking for some assistance! I have a 2018 204 DSG high line. Had it from 8k miles, now has 82k on the clock. I’ve done all of the servicing and maintenance on it as I’m very mechanically minded and my business is automotive electrical design. However, I have a fault that I...

www.t6forum.com

Lumpy engine start and idle

lets see what plots @mmi can pull from the data.....:mexican wave:

www.t6forum.com

Spoiler: Engine build-in diagnostics tests

Also quite a few engine build-in diagnostics tests that can be run for further analysis by VCDS - extremely powerful diagnostics tool.

[T6_measured] 01-Engine - Built-in test for EGR

So it seems - inevitable P0401. Well, visited a VW garage to be tested - the van had accumulated 30 events in ECU's memory since July 2021 (since 20 months now). Eventually managed turn on the emission light at event number 31 - thus had a priviledge to have EGR flow tested. The result -...

www.t6forum.com

EGR Valve Self Test Procedure (IDE00242)- P046C?

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi...

www.t6forum.com

[T6_measured] 01-Engine - Built-in tests for turbocharger

01-Engine - Basic Settings IDE00457-Test of turbocharger HOW-TO run engine's built-in test for turbocharger Engine running VCDS > Select > Engine > Basic Settings > IDE00457-Test of turbocharger Select "Measuring Values" Pick up e.g. the following data items for monitoring: IDE00021 Engine...

www.t6forum.com

[T6_measured] 01-Engine - Built-in test for Transfer fuel pump

A quick DIY way to test fuel lift pump's basic functionality. The test takes advantage of engine's fuel high pressure sensor (in fuel rail). Running the lift pump continuosly makes the pressure eventually "leak" through high pressure pump and can be detected by fuel pressure sensor. As a side...

www.t6forum.com

Anyways, more than happy to help to try to analyse data files

---

Service history? Has the fuel filter has been replaced - although not the prime suspect for the symptoms?

Last night I’d been to the gym so the van was at full operating temp when I arrived and had cooled a bit in the 45-60 mins I was in there.
It did its usual misfiring for the first mile and possibly just as it returned to normal, the EML came on.
I’ve bought Carista just to see what the code is and I’m getting the following.

P245700 - Exhaust Gas Recirculation Cooler Efficiency Below Threshold



P245700 - Exhaust Gas Recirculation Cooler Efficiency Below Threshold
Looks like it could’ve been an EGR fault all along.
@mmi , would you say this means the EGR needs replacing? Or is there anything that can be done?

Thanks

 

[mmi]

Difficult to imagine how the above fault would have caused misfires.
Also the code is about EGR cooler preformance, not the EGR itself.

I believe the ECU simply monitors exhaust gas input and output temperatures (as there are sensors for those) so basically the ECU doesn't see cooling effect between input and output of the cooler. I would say worth checking coolant pump of the EGR cooler before replacing any parts.

Below a measurement of EGR cooler input (red) and output (output) temperatures - from 200 to 1000 seconds exhaust gases are fed through the cooler which cools them down very effectively. Then from 1100 to 1800 seconds EGR cooler is bypassed thus much higher exhaust gas temperature is seen at the output (blue) of the cooler.



More details in

[T6_measured] Winter specialities

Spot the winter specialities:

www.t6forum.com

 

[Jimbo160]

I’m just guessing here but could it possibly be an air lock in the cooling system? The garage I got the van from didn’t mention that they’d changed the coolant. But it is very fresh looking.
Is there a way to bleed the system?

 

[mmi]

possibly be an air lock in the cooling system?

When you open the cap in coolant bottle - does the level rise? If there is air in the system it would rise siginificantly on hot engine.

it is very fresh looking.

It should stay fresh looking for many many years.

Is there a way to bleed the system?

The filling should be done by using a proper vacuum filler.
Also could run ECU's built in procedures to clear both coolant circuits.