Technical Doblo 1.3 limp mode or maybe not?

[bokoshoko]

I have a new to me 64 plate Doblo chassis cab with the 1.3 diesel. It went for an MOT and the tester mentioned they struggled to get it to 3k RPM. The trip to the MOT test was pretty much the first journey I'd done in it as I'd spent time doing a bunch of work.

Long story short it definitely seems to not go over 3k in any gear. It will momentarily but always pulls back down to 3k. OBDII reader showed no faults, initiating a forced DFP regen proved that the car will raise to 3.5k and hold with no issues and the regen completed successfully. Live data feeds show throttle pedal position sensor is working. I can not get the thing to generate any codes at all.

I don't want to just throw parts at is in the hope I get lucky. The absence of codes is a real challenge though. Wouldn't I be seeing DTCs if this was an issue with a blocked EGR or DPF? When the van was in forced regen mode it sounded fine, no loud hisses suggesting boost leak, it held the 3.5k for 15 minutes, did not overheat, no black smoke...

Close to getting to Fiat at this point as I'm out of ideas - any thoughts? Thank you

 

[Abarthmultijet]

What scan tool did you use?

 

[bokoshoko]

Hi used a TopDon TopScan (https://eu.topdon.com/products/tops...vRViPZqLd0-rjU3q1CXJsBQRn8gd8wpN9ViPoUyZbMGnk)

I've used it before on another car and do know that it gives accurate results. It was also how I triggered the regen and ran tests on the instrument cluster (that's how I found the previous owner had used black spray paint to "reset" the service indicator!)

 

[Abarthmultijet]

Ok, not familiar with that one. Maybe worth the hassle and go to the Multiecuscan register and find someone in your area, than you know 100% sure there will be not any fault codes the other scan tool can't see.


In an extreme case; you can program an engine ecu to not show any codes.

 

[clayts450]

At a guess, it sounds like the Dobbie has been speed restricted. I had a speed restricted 2015 Vauxhall Combo (ex Mitie) and a 2017 Vauxhall Combo (again ex-Mitie) that wouldn't rev past 3000K. If it's an ex Auto Lease vehicle chances are it has an aftermarket speed limiter box hidden somewhere behind the glovebox or near the fusebox. May be called something like Romatic or similar - there's usually four screws you can undo on each corner of the box, and inside is a fuse. Pull the fuse, speed limiter gone.

Failing that it could be hard coded, something which MultiECUScan can remove, with the right cables

 

[bokoshoko]

Hi, I did wonder if it's a deliberate configuration. It's first owner was Scottish Borders Agency, I can well believe it was rev and speed restricted. It's the absence of any DTCs along with a completed regen that make this "feel" intentional and not a limp mode.

 

[Abarthmultijet]

At a guess, it sounds like the Dobbie has been speed restricted. I had a speed restricted 2015 Vauxhall Combo (ex Mitie) and a 2017 Vauxhall Combo (again ex-Mitie) that wouldn't rev past 3000K. If it's an ex Auto Lease vehicle chances are it has an aftermarket speed limiter box hidden somewhere behind the glovebox or near the fusebox. May be called something like Romatic or similar - there's usually four screws you can undo on each corner of the box, and inside is a fuse. Pull the fuse, speed limiter gone.

Failing that it could be hard coded, something which MultiECUScan can remove, with the right cables

If it is coded in the engine ECU you can not remove it wiht MultiEcuScan. You need an eninge ecu tuning company

 

[clayts450]

If it is coded in the engine ECU you can not remove it wiht MultiEcuScan. You need an eninge ecu tuning company

Fair point. I think if it was a bulk order of vans for the Borders Agency then they may well have been hard coded at the factory.

However, if it was aftermarket then it could be coded via a diagnostic tool or (as I noted) even by an external box (I know Lex Autolease used these as I've successfully disabled two of them).

This is the simulation screen in MultiECUScan from my 2018 Doblo

 

[Abarthmultijet]

Yes indeed, but when there is an speed limit set with MultiEcuScan it isn't rpm restricting. It is litterly speed restricting.

 

[clayts450]

Yes indeed, but when there is an speed limit set with MultiEcuScan it isn't rpm restricting. It is litterly speed restricting.

Equally a very fair point.

I know that on the Doblo the specifications most used car sites use list a vaiety of different speed limits, rather than a rev limit.

Is a rev limit hard coded by the factory then ? To me it sounds more likely it's an aftermarket box. As I say, only going on my experience with the Combos.

I'll see if I can dig out the photo of the box Lex Autolease used - that was definitely rev limited

 

[clayts450]

This was the one in the Combo (may have been an earlier variant). The screws in each corner can be removed. Inside the box is a fuse. Take it out. Rev limiter defeated

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[Abarthmultijet]

Yes it can indeed be both. Hoping it is an hard box. Most simple and easy fix. Find the box in the car somewhere

 

[bokoshoko]

Thanks all, I'll go searching at the weekend.