Mk5 Golf GTI throttle body replacement

[Jimmy No Hands]

I have an 06 GTI with a TB issue, have sourced a revision Q version to replace it with, just wondering how easy this is to do at home, and whether anything needs to be updated via VAGCOM or whether it's just a straight swap.

Thank you for any help.

[DEANO87]

The throttle body will need basic setting with vag com or similar equipment. What's the issue with your current throttle body? I find carrying out basic setting fixes 9 out of 10 throttle body issues and doesn't always require replacement.

[Jimmy No Hands]

It has a really intermittent fault, very irregular but eventually will kind of sort itself out. Will randomly go into limp mode and the EPC and ESP lights will illuminate. I scanned it and it had these codes saved; P0221 and P1564. We ran the calibration and the values seem to stay at 88% and 12%, is this how VAG set them or is the throttle slightly sticking? i was going to update with the latest revision TB (which I've bought) but I'm hoping it just needs a thorough clean.

I should add most of the time it's boosting fine and the throttle feels spot on. Hoping it's not an electrical issue but could explain the randomness.

Edited by Jimmy No Hands on Tuesday 28th October 08:00

[SuperchargedVR6]

Yeah those numbers are normal. The throttle's natural "stop" is 12% open, which is the limp home feature. The throttle motor moves the blade in both directions.

When you press the gas pedal whilst plugged into the diagnostics, you will see 88% reduce and 12% increase. There are 2 pots (aka variable resistors) in the throttle and 2 in the pedal. The ECU constantly compares them and if any of them disagree, the ECU cuts power to the throttle motor. This is the standard DBW safety feature, so worst case is you do actually have a dodgy throttle, and best case, a weak battery or dirt on the throttle body.

Changing it at home is not pleasant. The 4 bolts face down and 2 of them are a real b1tch to get to. If you do replace the throttle, replace the O ring as well. I'll be surprised if a new throttle is less than £300. Even though have a cheap plastic blade instead of metal, failure of these is very rare.

If you want to try and throttle realignment, the procedure is on Ross-tech's website.

[Jimmy No Hands]

What would you suggest would be the next step? I've cleared the codes and it was fine all of yesterday evening. I have a replacement TB but happy to keep as spares if the current one is still good. Is it worth giving it a thorough clean? I'd like it sorting really, it is fairly irritating as you can imagine :-( thank you for the help

Edit: we did a realignment too. Will have to see if it resurfaces.

[SuperchargedVR6]

OK, take the boost hose off and using a clean rag soaked in carb cleaner, give the throttle a good clean. You'll need to prop the blade open whilst you give it a good wipe around. Not easy when the throttle faces the floor! Whilst you're in there, check the throttle harness for any signs of chaffing.

Disconnect the battery for 10 mins. Reconnect. Switch the key to ignition 2 and leave it there for 5 mins. The ECU does a throttle alignment when you reconnect the battery, so no need to do that again manually.

See what that does. If the codes keep coming back, I would replace the throttle. Those codes translate as "throttle drive angle" and "throttle under voltage" faults, so it is all related.

[Jimmy No Hands]

Righto, will do that tonight. Probably easier than struggling with the four bolts. Although getting in and around with the access you have is probably pretty tight too but I'll give it a go! One of the connections looks rather beat up, albeit no obvious splits in the wire itself.

Jim.

[SuperchargedVR6]

How'd you get on? I forgot to mention, if you drop the undertray and place an old mirror on the floor, that will help with seeing what you're doing to the throttle!

[Jimmy No Hands]

Honestly not got around to it, ran out of time last night. Strangely enough, touching wood (oo er) its been completely fine the past two days to and from work. It's booked in with R Tech in two weeks time for a stage 1 and a health check, so hoping it behaves until then.

If it reoccurs I'm going to do as you instructed, time will tell!