[Apollya]

Did I miss any diesel engine common faults?

You missed fuel dilution due to failed or incomplete DPF regens, excessive engine, turbo and oil system component wear, cylinder compression loss, failed crank shaft, timing chain failure. There’s probably more but already now a relatively extensive list.

For the record, I decided to do like you did before my diesel s&*t the bed again and became uneconomical to repair, sold it for fairly pitiful value, but at least it’s someone else problem now and am buying petrol only.

 

[ianjude57]

Had the same problem, got it remapped, egr delete, perfectly clean throttle body inside now and 350 bhp. Cost £ 250, well worth it.

 

[cutlea01]

Aside from making your car illegal.

 

[ianjude57]

Who can tell, lol 😆

 

[diesel]

Who can tell, lol 😆

MOT

 

[ianjude57]

MOT

Not possible

 

[Mohawk]

Please explain why "not possible" ?

 

[ianjude57]

Mot tester does not know if egr works or not, no way to investigate

 

[Mohawk]

So you are saying your car has passed multiple MoT's complete with emissions tests ? With the EGR disabled ?
I know my previous 4x4 precluded brake tests & driving emissions tests, due to MoT station only having a 2 wheel drive rolling road. So they can't do rolling road brake & emissions testing. Just idle & rpm hold tests in neutral & a test drive for the brakes.

 

[cutlea01]

Mot tester does not know if egr works or not, no way to investigate

This is correct, the MoT does not test nor look for a working EGR system. Missing exhaust components such as no DPF, Cat or adblue, yes. I've removed or disabled EGR systems on diesels and no issue with MoTs, but I had to add the comment in #23 being admin in case a FM reads this in the future etc.

 

[Penfold]

I would agree, illegal but not picked up by mot.
I previously had a merc diesel that the adblue sensor stopped working which would have resulted in a full new adblue tank etc (high cost for an old car). Deleted adblue via ecu update and it wasn't then picked up via mot.

 

[ianjude57]

So you are saying your car has passed multiple MoT's complete with emissions tests ? With the EGR disabled ?
I know my previous 4x4 precluded brake tests & driving emissions tests, due to MoT station only having a 2 wheel drive rolling road. So they can't do rolling road brake & emissions testing. Just idle & rpm hold tests in neutral & a test drive for the brakes.

yes no problem, egr doesn't operate when being tested

 

[Lowlife92]

Any more long term updates on this? Going to give this a go at some point.

 

[diesel]

I'm pretty certain the EGR & TB butterfly are on off only.

as it turns out both EGR and butterfly are variable flow controlled by the ECU (PWM). The amount of open or closed is adjusted by feedback of engine sensors.

 

[Mohawk]

How did you ascertain this information ?
AFAIK EGR can only work on a closed throttle & as Diesel does not have a throttle they added the butterfly into the intake to create the necessary vacuum.

As to whether the EGR valve in the exhaust takeoff is variable or open/closed I have no knowledge.

 

[Mohawk]

Any more long term updates on this? Going to give this a go at some point.

Well both TB's still work. No issues stock, but have had a few temporary DTC's, still looking into those. But with the tuning box still get the dreaded Turbo over boost condition.

I refitted the new TB modified with the adjustable stop & did 250 miles combined driving then took it up the hill that always causes it & bam restricted performance ☹

Done some more research & the issue may be related to a sticky actuator which I intend to look at this weekend

I have modified the new TB to have the stop & took a load of pics, so will do a write up on that soon. Sorry silly busy ☹

 

[diesel]

How did you ascertain this information ?
AFAIK EGR can only work on a closed throttle & as Diesel does not have a throttle they added the butterfly into the intake to create the necessary vacuum.

Looked up engineering notes, and troubleshooting information.
Studied Euro five and euro six emissions design engineering papers.
JLR (and most euro six engine) use a dual EGR system.
One high-pressure and one low pressure system.
This system uses PWM (pulse width modulation) to actuate both the EGR flow, and the butterfly as you call it. The butterfly has two purposes. (1) during engine shut down to completely close off intake air, and reduce compression to near zero, to prevent engine shake that can damage timing chains. (2) to regulate and increase EGR flow by causing a low pressure to draw in exhaust gases. if the butterfly closes completely, the engine loses all compression (as stated above) and shuts down. If the EGR is open and the butterfly is closed, the engine will not run on 100% exhaust gas.

As to whether the EGR valve in the exhaust takeoff is variable or open/closed I have no knowledge.

This system uses PWM (pulse width modulation) to actuate and regulate the EGR flow.

if either of these systems was just on and off there would be no need for PWM and position sensor feedback to the ECU that could just be accomplished with a switch. the ECU uses multiple sensors too adjust the amount of EGR flow at both the EGR valve and the butterfly. and yes, the butterfly is spring return just like most EGR's (although some EGR's are not) this is because it's not a stepper motor. the PWM simply pulls against the spring at variable amounts, and the position sensor tells the ECU where it is at any given time.

Note: I think your confusion with the butterfly is from the original old school use on diesels to stop the engine shake when shutting the engine down. Many of the old version were just on or off only and only had one purpose.

 

[Mohawk]

No confusion re the butterfly's purpose. Any old school diesels I have worked on never had one, as to kill a diesel you just shut off the fuel & the engine winds downs nicely. No chains to worry about on most modern engines.

I assumed the actuator was on/off like a solenoid due to the spring return. Why you would use a PWM strain motor instead of a stepper motor is beyond me, possibly for its instant open capability as stepper motor would be slower. Again the whole Euro6 Diesel config is just a fudge & achieves nothing in real terms.

I thought the new SDV6 only uses a low pressure EGR & the takeoff is after the DPF, supposedly to reduce soot ingestion, but does not appear to work well, so I'm working on an EGR gas flow filter idea to capture most of the soot. Apparently the manufacturers know that the soot ingestion kills the engine, why both filtering intake air then allowing hard carbon particles straight in from the exhaust ? Research shows that 5-20um are the worst & that is a lot of the soot that gets ingested!🤷‍♀️ They knew it would be a problem, but decided NOT to add a fine particle filter to the EGR gas circuit, because it would require regular maintenance, by that they mean owner accessible so it can be emptied & reverse flushed. So I'm working an idea for one of these.

 

[Apollya]

Just to pipe in on DPF internal gutting, EGR blanking and remapping.

MOT testers currently do not look for these, but there are changes coming supposedly to actually test for the emissions systems being there and working as intended.

it also invalidates insurance (although you could get another remap and remove the blanking, but you can’t refill the guts of the DPF easily) and in the event of an accident would be classed as non-road legal vehicle, which could lead to numerous diff types of prosecutions.