Throttle Valve Angle vs Pedal

[MikeBee]

Hi all,

I'm trying to debug a flat spot on my ED30. Basically from 3.5k rpm to 5k rpm there's a lack of torque.

Logged data from some 3rd gear pulls in VCDS shows slightly low MAF values at the top end (peak 265 g/s) but the thing that looks wrong is that during the area that feels low in torque while I am at 100% pedal position I don't get 100% throttle valve angle. It drops to around 40% suddenly and only after 4.5k rpm is starts to come back up. Even above 5k rpm it still only ever gets to just over 90%.

The whole time the fuel rail pressure is 110bar and the fuel pressure a solid 4.5bar. Boost target tracks measured boost nicely too. I've also fitted a brand new G DV recently, but not checked the PCV or cleaned the MAF so these are on my list to look at today.

Is the throttle mapping behaviour normal?

Thanks.

[jhook661]

Hi mike what's the spec and who's mapped the car ?

[MikeBee]

Completely stock in terms of spec.

The only smell is the flash counter shows 1 but afaik it's never been mapped...

[Tfsi_Mike]

Completely stock in terms of spec.

The only smell is the flash counter shows 1 but afaik it's never been mapped...

Could be a dealer oem update at a service?

[MikeBee]

Yeah it's got a fairly full VW service history (up to Nov last year) so it could be.

I think peak air mass flow would be higher if it had been remapped. The value of 265 if anything is a bit lower than stock!

[MikeBee]

Sorry ignore me I'm being an idiot. It's 165 g/s peak MAF value.

[Tfsi_Mike]

Yeah, was about to say. That's a good figure! Haha

[Dan_FR]

*edit* Ok... 165G/s is a little low for an Ed30, so something isnt right. Take a look at the APR logging guide, get them done and shared on here: http://www.goapr.co.uk/support/datalogging.php

[MikeBee]

*edit* Ok... 165G/s is a little low for an Ed30, so something isnt right. Take a look at the APR logging guide, get them done and shared on here: http://www.goapr.co.uk/support/datalogging.php

Thanks, yeah that's what I followed to get the numbers. Glad to know I'm on the right page 

Not sure the best way to post up the log, but below is the most consistent of the four pulls I did. The odd looking part is highlighted in green.

[pudding]

TC closing the throttle to control wheel spin?

Full throttle pulls should be done in 4th really as it's a 1:1 ratio, therefore the engine is doing all the work.

Everything looks normal there apart from Engine load not meeting the target.

ECU flash count should be zero on a totally standard car.  I don't think there were any updates for UK cars.

[MikeBee]

Cool thanks.

There's not enough torque for the TC to come in although I can repeat with it turned off. Good shout.

If the flash counter should be zero then probably just a terribly done tune!

[Dan_FR]

Doubt its a tune as such, anyone with the tools to flash a map would be able to increase the load request without touching the fuelling, resulting in more boost and an ECU that can cope with a 25% fuel adjustment to give you a sizeable increase over standard

Could well be the stock mode from software such as Revo or APR that often defaults to a flatter boost profile and has less performance than standard. Found that with my car when I bought it, had Revo software that had been returned to 'standard' performance

Will look at the image above later, can't access any media in work

[pudding]

Cool thanks.

There's not enough torque for the TC to come in although I can repeat with it turned off. Good shout.

If the flash counter should be zero then probably just a terribly done tune!

Had another thought earlier.....it could be a sign of a throttle body on it's way out.  There is info on the net about MK5 throttle / throttle wiring loom issues, and the throttle part no. has changed a couple of times.

It could also be what Dan said.  My Revo map was like that when disconnecting the battery, it reverts to what they call a 'Stock like' map, so isn't the actual VW map, but a copy of it.  Maybe something in their version of it isn't quite right but a standard map felt better and more consistent to me.

[MikeBee]

Cool thanks everyone, this is really useful.

I will keep investigating!

[MikeBee]

I may have found the issue while cleaning the MAF sensor and checking the PCV (which was fine).

The seal between the MAF sensor housing and the turbo inlet hose was pinched and not sealing properly, giving an air leak after the MAF sensor.

I've sealed it correctly now, but the seal itself is stretched and could do with replacing. Anyone know the exact part number?