Strange engine behaviour at low rpm and throttle

[vexedben]

Hi everyone. Recently had my van stage 1 remapped and it’s so much better than the old stage 1 remapped it had. I’ve noticed at very low engine speeds and light throttle application, there’s a strange behaviour with the engine albeit happening very infrequently. Mainly noticed it when just starting to apply throttle slowly there’s what feels like a very small pullback on the engine, like the ignition being retarded, and then the engine picks up and goes absolutely fine. Just wondering if this is likely to be a mechanical issue or if I need to explore this with the garage that did the map?

Cheers, Ben.

 

[Dellmassive]

If it's been mapped you have lost the OEM reference point.

You will need it at a mappers with rolling road to check the plots.

Could be anything.

Maf sensor readings
Injection duration or quantity.
Boost pressures

Aside from that it could be a hardware issue, again dirty maf. Dirty injectors etc etc...

Mapped vans can get blocked dpf if it's not deleted.

I'd say back to the garage.

Keep us posted though.

 

[Pauly]

Are you confident it’s not doing a dpf regen ?

 

[vexedben]

If it's been mapped you have lost the OEM reference point.

You will need it at a mappers with rolling road to check the plots.

Could be anything.

Maf sensor readings
Injection duration or quantity.
Boost pressures

Aside from that it could be a hardware issue, again dirty maf. Dirty injectors etc etc...

Mapped vans can get blocked dpf if it's not deleted.

I'd say back to the garage.

Keep us posted though.

Ok nice one. Thanks for the info, I’ll bob it back to the garage and have a chat through then. Remapped vehicles are pretty new to me so just wanted to make sure it wasn’t anything glaringly obvious.

 

[vexedben]

Are you confident it’s not doing a dpf regen ?

Not too confident to be honest. So far I’ve only been doing relatively short country road journeys of 20mins ish. Could very well be regenerating but I’ve never noticed it as the issue has tended to be whilst I’ve been moving so never seen an elevated rpm like I would at traffic lights. Food for thought though.

 

[StratosFearXX]

Take it for a decent run. They don't like short journeys.

 

[Pauly]

DPF regens alter ignition timing to help increase exhaust temperatures which sometimes feel like a slightly lumpy idle/hesitation to rev
If your only doing short journeys you could be stuck in a loop of non complete regens ??

 

[vexedben]

Evening guys. So I’ve had chance this week to give the van a blasts to try complete a dpf regen. Hasn’t seemed to make a difference in terms of behaviour. What I have found is that it is especially noticeable in 3rd/4th around 1400-2000rpm for any given throttle input increase. The sensation is very much one of feeling initial torque of the engine then it drops like the boost/fuel has been held back then kicks in again once it’s reset itself. Hard to explain I suppose.


It’s making me wonder if there is something software limiting the map within this rpm range for the given fuel/boost settings of the map.

Plan is to get it to the garage and have a chat through about it and work a plan. Just trying to get that arranged in the meantime.

Any ideas?

 

[vexedben]

Just a quick update, after a lot more driving I think this is just more turbo lag than I’m used to at low rpms and not being used to driving a van. I think the combination of dpf regen at lower rpms was causing the weird jerking especially on and off throttle like driving round town yields. Case closed

 

[StratosFearXX]

Just a quick update, after a lot more driving I think this is just more turbo lag than I’m used to at low rpms and not being used to driving a van. I think the combination of dpf regen at lower rpms was causing the weird jerking especially on and off throttle like driving round town yields. Case closed

Is this a DSG? The gearbox can be mapped as well if so.

 

[vexedben]

It’s a 6 speed manual unfortunately.

 

[StratosFearXX]

It’s a 6 speed manual unfortunately.

Well at least it's not a DSG problem ... I'd be suspecting the remap to be the problem ...