3.0 CRD Surge/Misfire/Hesitation Diagnosis

[afnan]

Hi,

I recently have a TIPM recall done on my 13 GC eco diesel. After that, I noticed that from 1000 to 1500 I get a surge or misfire feeling. After 1500 RPM the car becomes live and roars like a lion.

I think two Possible issues might be causing this.
Issue - 1

At idle:
I previously posted some PID data. I come from a petrol engine background and had no clue how fuel trims work in diesel. It appears that injector 4 has +4 fuel correction at idle which means it is adding fuel.

At 1500 RPM:
The fuel correction that was 4 goes down to zero. In fact all injectors go to zero. This means that when the pressure increases the corrections get better.

Possible Cause
Since the set pressure and actual pressure values are same this could mean that injector 4 is clogged. However, I cant see in history if anyone has ever replaced the fuel filter. I would imagine it would be really dirty and will replace and see how it goes.

Issue-2
When I unplug the EGR orange connector the sluggishness and surging vanishes. The injector correction values are not affected by this. This tells that injectors are not the main culprit - EGR is.

Possible solution
Will remove and clean to see if it makes any difference.


Does my approach makes sense at all?
What

[drover]

You will need 2 x fuel filters, I change mine at 20K...........

Its a worry that it has a misfire, that can be very serious in a CRD something I haven't come across.

Have you cleaned the MAP sensor ???

Its worthwhile to do this as it could be the cause of all your problems, if the vehicle has been serviced by a dealer then its more than likely clogged up.
Lots of folk jump to these complicated, costly reasons at times when the basics haven't been covered, not saying its not the injector I only pull out the meter after Ive gone over the simple stuff first, filters, sensors, engine covers rubbing through wiring etc.
Whenever I buy a new 2nd hand rig, I change all fluids and filters, in mine it had been 1000km since the stamped service, I found a number of things that were supposed to have been done but weren't, I don't follow the Jeep schedule anyway as I think its set up more for lower servicing costs and the magic economy figure than whats best for the vehicle, always have run my own and find my rigs are trouble free for the rest of their time with me.

[Treebreakerbob]

Are you aware that in the 5 speed models there is the torque control program to not overload the gearbox when changing gear etc, my MY13 also is a little bit flat from 1000 rpm but not rough also has always been a bit injector noisy in first gear from new. I have put this down to programming. They knew damn well the gearbox was being stretched by the VM Motori engine but did what they did to make it last, pity the torque converter was not up to scratch either, most builds after 2012 were better

Big possibility fuel filters or maf sensor needs cleaning

Bob

[afnan]

MAF sensor is clean. MAF is clean as well. I think if this misfire goes away when I unplug EGR it has something to do with EGR

[peteynut]

Same symptoms and solution on my 2015 diesel. Would be sluggish, occasionally felt like big misfire on very light throttle. Drove fine as soon as you gave it a bit.

Unplugged EGR with engine off and confirmed EGR closed. Runs perfect now, fuel economy improved, power for first 30% of throttle better. Not as sluggish in throttle response. But most importantly none of the misfire/surge issues.

I know EGR is not the best device for performance but I believe there is something wrong with it to cause so many issues. I have not pulled it off the car to inspect it but at this stage I will just get a tune done to turn the EGR off so the engine light isn't illuminated.

But you are not alone I have had the exact problem and same fix.

[Troutman]

Have you pulled the EGR diffuser out for a clean?

[peteynut]

Not yet. Noeco blank off plates just showed up so will be removing it completely. (diffuser that is)

If diffuser was blocked, that would lower the EGR flow which would not explain the issues as best I can understand. I suspect EGR internally either bypassing/overflowing causing bad air mixture. Also losing boost through EGR maybe? the same throttle now nets around 3psi, where before would be around 0.8 while misfiring. Alternatively the misfire could explain the low boost also.