Anyone removed the throttle body ? *** help with issue please ****

[Madone]

I need to remove the throttle body, has anyone done it ?, how simple was it ?.

The guides seem to indicate it's pretty straightforward from underneath with 4 screws holding it in place. Remove rhe pipe from the intercooler to the throttle body then unbolt the body ?. Guess it's best to clean it with carb cleaner ?

[Dan_FR]

It's not difficult to do - the difficulty is accessing the 4 screws that hold it to the manifold as there isn't a lot of room. It was worse for me as my uprated FMIC meant there was even less room in the engine bay as it pushes the rads further back. Get the intercooler to TB pipe out of the way completely.

Not sure I would clean it at all - I highly doubt it is 'dirty' and the TB is electrical.....

[Madone]

Thanks

Yea my cooler has pushed the rad back so less room than before

I am still chasing this dropping revs issue, changed and checked all vacuum hoses, pcv is fine, been through just about everything, logs don't indicate a air leak, adaptation for idle and loads are both below 6%, in fact  the idle correction is taking fuel out, which would indicate it's getting less air then expected. Fitted a new MAF, didn't fix it. Car runs fine with MAF disconnected though. Any ideas mate ?.

Thanks

[Madone]

It does this, but doesn't stall. The rpms only drop after putting the engine under load, doesn't do it just reving on the drive.

Changed the intake back from the vWR to stock and it's improved but still does it although to a lesser degree.

[Madone]

It's not difficult to do - the difficulty is accessing the 4 screws that hold it to the manifold as there isn't a lot of room. It was worse for me as my uprated FMIC meant there was even less room in the engine bay as it pushes the rads further back. Get the intercooler to TB pipe out of the way completely.

Not sure I would clean it at all - I highly doubt it is 'dirty' and the TB is electrical.....

Being electrical won't make any odds to the butterfly getting gummed up, seems to be a known thing (from what I have read) which can affect idle. The opening of the butterfly at idle is tiny so some gum could easily make that restricted. I'll try anything at this point

[pudding]

Any fault codes as you've got the CEL on there?

I replaced the throttle on mine recently (to chase a different problem) and it made zero difference.   That's the thing with electrical parts, they either work or they don't.

VW did revise the TB a few times though, and there was an issue with the wiring loom that fed the TB shorting out on some cars.  I checked all that when I was in there and all looked good.  You normally get a throttle specific CEL if the pedal and throttle position misalign by a prescribed amount.

The trickiest bolt is the rear one adjacent to the alternator, but doable with common hand tools.

[Dan_FR]

What intake and software? Trims closer to zero the better, both my idle and multiplicative trims are within 1%, this goes up a little after booting about with the Meth active, but the car drives fantastic compared with previous intake I had when trims were higher.

When I had a rev drop issue like that I had a pretty big vacuum/boost leak and I watched my instant trims climb in to the high teens (i monitor them with Torque app)

My comment with the TB and cleaning was more so getting the TB wet with cleaning fluid - it's an electrical device containing servo/motor etc. Not sure I'd want to drown mine in fluids... Especially when Meth (for instance) is known for killing the TB when injected before it.

As above though, you would get a code if there was an issue, and VCDS wil ltell you the TB position at idle. The ECU is very good (and quick) to pick up TB faults.

[Madone]

No codes at all, revo stage 2+ software and I was using a VWR intake, to rule out MAF scaling I switched back to OEM airbox. It's less with the oem, doesn't jump as high after dipping below tick over. But Still does it to some extent. With the VWR It can dip to 520rpm them recover to 1000 then settle back to idle.

Had a smoke test done, checked the pcv, swapped the diverter valve, replaced all vacuum hoses to and from the vaccine pump. However the trims and the way the car drives really doesn't indicate a leak.

I have calibrated the throttle body with vcds, looking at the logs the throttle is doing what is should. When the revs dip it closes to a value less than idle, so looks like the throttle is doing the right thing. AFR seems ok, it's def not lean indicating a leak. Car idles fine, solid as a rock. Have logged with the maf disconnected and the throttle doesn't close as far as it does with the MAF connected (so the revs don't dip)I'm thinking if the throttle is gummed even an bit it's allowing less air for a given opening (based on the MAF reading). But with MAF disconnected it relies on map which is absolute value after the butterfly. Which all kind of makes sense ?

TBH I am running out of ideas and don't want to keep replacing bits for no reason. I mate who is a master tech at Audi has been looking at it too, he hasn't seen this before (after ruling out the obvious leaks etc).

It's a real annoyance 

[Dan_FR]

My guess- the intake. If you know someone with a Revo I'd highly recommend trying it. If the TB was at fault then the issue would be there all the time. The TB is doing as it's told by the ecu.

[Madone]

The oem intake should work fine, I've ditched the VWR just in case it's the MAF scaling but it's still not right in the oem airbox. I ran the oem airbox on this software for a year without issue, so something has changed. Like you I thought intake but no such luck. It is better on the oem, so maybe the correct scaling helps, but I still haven't found the route cause. It's just amplified by the VWR system. 

[pudding]

Yeah, it's a classic sign of the mixture being too weak when the throttle closes to the idle position.   The revs bouncing is the ECU trying to recover the situation, but lambda isn't fast enough to fill in a big fuelling hole.  So I'd be looking for an air leak down stream of the MAF in the first instance.

If not, it could be a dirty throttle but personally I've never seen that so bad it physically stops the throttle plate from moving freely.

[Madone]

I don't think there is a leak as the trim for idle is fine, in fact taking fuel out rather than put it in. Like Dan said with a air leak the idle trim goes into double figures quickly. I have pulled the dipstick up very slightly to create a leak and the trim shoots up.

I don't think the actual throttle movement is getting hindered, but if there is gum on the butterfly or the body it will restrict air past the butterfly at a given opening. Not sure what to even try if this doesn't work !

[pudding]

My old VR6 used to behave exactly like that when the idle mixture wasn't right.  Usually it was the MAF, but you've done that already.  Was it an OEM MAF?  Did you pull the battery after fitting it to let the ECU readapt?  With the VR6, if I didn't do that, it would carry on ignoring the MAF and substituting the signal with a different sensor.

My throttle was 105K miles old and other than a squeak from the spindle when moving it by hand, it was fine.  A bit grubby, but it moved perfectly.  I'd be surprised if the throttle is the cause of your issues, but as I said, VW have modified it a few times, so never say never!

[Madone]

I do wish it was something more obvious, as you mentioned i didn't at first disconnect the battery, Once I  did that, I thought it had been fixed (with the oem intake fitted) but then it came back, all be it at a reduced level from using the VWR intake. 

It has also done a longer hunting thing, where it bounces between 800 rpm and around 1000 rpm, it was bouncing between these two levels for about 15 seconds. I have the logs for that and the throttle is opening and closing to cause this. I can't work it out. The throttle calibrates ok so doesn't appear to be sticking. Can only hope it's gummed up which is restricting air flow making it harder to control the idle.

Any ideas anyone has would be appreciated !