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Update on throttle body clean / replacement air pipe .. all went wrong

mk4 golf 1.6 8v 1999 AEH engine code

After replacing the air pipe between the airbox and throttle body with a new pipe as old one was damaged. All replaced well, new jubilee clips on and VW ones shoved in the bin.

I now have eratic or hunting as the mechanic called it. Basically in drive everything is fine idle wise it drops to about 900 rpm. In park however it shoots up to about 1200 rpm and stays theres. Sometimes it drops to 1000rpm then if you touch the gas pedal it shoots up again.

All I did was replace the air pipe between the air box and the throttle body and then I carb cleaned the throttle body (did not remove it just cleaned in situ) then I used the throttle wire to open the butterfly to clean a little deeper down. Which according to the mechanic may have broken the stepper motor (valves) on the throttle body or dirt has gotten into the valves.

I have no idea how dirt could have gotten into the stepper motor.

After searching on a mk4 golf forum and reading as this car is DBW I used the throttle cable to open the butterfly and clean down the back of it, after reading it seems doing this is bad and can upset the "home settings" of the stepper motor if neck wreck it.

and it also said it would be new throttle body time.

I hope that isn't so as there about £200 odd I think.

On my golf a 1.6 16v 2001 I lift the engine cover spray wipe drive and no problem at all. But on my sisters golf its a world of hassle as above really.

I didn't take the TB off just cleaned what I could get to as it was.

One thing to add on the Air flow meter I sprayed a little carb cleaner down it as it looked a little dirty ... I'll put the carb cleaner away and not touch it again lol

I paid £30 for a diagnostic scan (no fault code lights on) :

I have fault code 00533 idle speed regulation

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00520 air flow/air mass

00523 intake air temp sensor

Now all faults were cleared and the only one that came back was 00533 idle speed regulation which has led the mechanic to think the stepper motor valves are dirtyhe said even a spec of dirt could cause this.

My neighbour who's an ex audi tech said I should just get the throttle body aligned by diagnostic computer and see how it drives from there or just drive it around for a while as I tampered with the throttle body and it should usually re-learn the settings and idle correctly once the new settings have been earn't.

any ideas where I've gone wrong (be nice) lol ... you ever start a job and wish you never did

Reply to
Stephen
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He is right.

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You need someone with VCDS or a dealer computer.

Reply to
Chris Bartram

Oh, and it's probably better to remove it to clean it, but then you need to do the alignment, plus you need a new seal.

Reply to
Chris Bartram

Sadly the local garage want £50 for a 3 minute procedure and I don;t know anyone with vag-com... I'm struggling to get my vag com shareware and lead to work. It just won't connect with the car as I was hoping to run through the basic settings for the throttle body alignment.

Also after some thought and reading from ukmkivs.net the feeling there is if the rev needle bounces it strongly indicates a vac leak of some kind. Which got me on the thought of checking everything was present in the area of what I have touched. There is one thing missing which is an O ring which fits on the airbox / air mass meter end, I guess a small weep would cause these symptoms, its a £2.86 part from th dealer is is on order as its the cheaper of anything. (accordin to dealer computer etka)

A scan this morning on my sealey vag scanner is still showing all of the faults yesterday, the air flow meter fault is back and the intake air temp sensor and idle speed regulation. I'm wondering if this one o ring could kick up all these faults.

The thing is though the car obviously didn't have this o ring before, and worked fine. I wondering if all the commotion of changing the air pipe upset a ring of dirt sealing it lol or something like that ?

too add to all of this would a faulty ignition lead cause any of these as I took one off to see what the spark plug ocniditon was like and had a little trouble wiggling it back on, but it did eventually make a pop sound when it did go back on. Also remove the ignition lead part that goes on the coil pack to see how easy or hard it comes off as I planned on servicing it soon (never done before on this car) all went back on ok.

...Theres a niggly part of my brain saying I've upset something. And before shelling ou on expensive parts like genuine vw air flow meters at £165 and throttle bodies at over £200 best to actually diagnose the problem. I can swear I can hear a whooshing sound by the air pipe which is brand new and undamaged from what I can see ... pffft

I'm going to try and get this throttle body alignment procedure done first and then the o-ring and post back my findings.

Never had a prolem like this usally a broken, damaged part... just order new one fit and quit this is a little more complex for me, but am trying to have a go at sorting it before conseeding defeat and taking it to the garage.

ho hum

Reply to
Stephen

Forgot to add the fault with my vag com is vag com does find the lead, status is on ik, but if I try and scan anything it searches and says cannot initialize module... if I could just get it to work and sort the tb out would be great... time to google it. I tried changing the baud rate from 0 to 9600 no joy.

Reply to
Stephen

Ask on one of the VAG forums- Seat/Skoda/VW/Audi. There is bound to be a member near you who will to the TBA for a beer or two.

Reply to
Chris Bartram

I got the lead working got it registered for $99 about £66 odd well worth it for all the features I'll never understand how to use lol. ANyone performed the all important throttle body alignment a few times, unfortunately its not working. Its resets it, I can hearing a whirring but I still have iratic idle. All done after I cleared the DTC's etc as per ross tech wiki.

So I guess its time to figure out if vag com can help me check if the MAF is functioning with some live data logging or some such ... more blooming studying coming up...

I used to enjoy a bit of home diy but now it annoys me .. apologies just feeling frustrated humpf

Reply to
Stephen

It's probably worth a really carefull check for air leaks.

Reply to
Duncan Wood

Sort the air leak out first. It won't work properly while it's still got that leak so fit the 'O' ring before believing anything the data says.

Reply to
rp

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