Z3 2.0 Throttle Body

[kingsgate]

Hi, can anyone tell me if swapping throttle bodies is simply that, swap it and drive away or is there some setup or 'pairing' to be done?

Also is the rubber 'O' ring sufficient to prevent air leaks or is there another seal / gasket to be used when fitting the new throttle body. The mating surfaces are flat and clean but I can't see how the 'O' ring fits in such a way that it prevents any leaks.

Thanks.

 

[GazHyde]

Just for my own interest, are you swapping like for like?

I'm sure one of the techies will be along soon...

 

[kingsgate]

Yes to the best of my knowledge it is a straight swap like for like.

 

[kingsgate]

Okay thanks for your thoughts on that issue, I think I'm chasing a fault with either the throttle body or the ICV but can't be sure. With the enging running if I attempt to blip the throttle the response is slow, revs go up but not straight away and the Rev drop is much slower. My throttle is cable operated and the cable is adjusted and working fine so why the strange response, there's no way you could blip the throttle for a downward gear change, the throttle response is way to sluggish. I've checked for air leaks several times but can't find one anywhere, I have no codes showing or EML, bit of a puzzle again. Any thoughts anyone?

 

[GazHyde]

@Brian H @Brian4 @zedonist @t-tony @Lee - any ideas on this one?

 

[zedonist]

When you Rev the engine from the throttle body is it still sluggish?

 

[Brian H]

Sticky/stiff throttle cable, these cable do degrade over time and the extra friction causes similar symptoms to the ones described above.

 

[zedonist]

You guessed where I was going Brian...my assumption is that if it is not throwing a code it must be mechanical. Do to rule system parts out, if the operation at the throttle body gives a normal response it is the cable as above, if it is still the same would think sticking butterfly or blocked idle valve.

 

[kingsgate]

When you Rev the engine from the throttle body is it still sluggish?

reving the engine from pedal or at throttle body gives exact same response, cable is good and correctly adjusted, throttle body and ICV have both been off and cleaned, it's a puzzle.

 

[zedonist]

Have you checked all the induction hoses for splits? there is a small one from the throttle body that usually perishes

 

[kingsgate]

Have you checked all the induction hoses for splits? there is a small one from the throttle body that usually perishes

I can't say I've Sen one from the throttle body, where exactly does it connect to? I've had all the usual suspects in the way of hoses off and most of them seem to have been replaced and are in good order. I recently changed the CCV and checked all those hoses at the same time, one was replaced because of a split but has made little difference to the running. If I remove the oil filler cap or dipstick the engine falters, tickover is steady and even. When I had the throttle body off I could see inside the intake manifold evidence of what may be a vacuum take off point behind the manifold, is there one there? I've considered buying the Bentley manual but have read that it doesn't cover the 2.0 engine as the manual is American and they don't have that engine there. I've been chasing what seems to me a lack of vacuum for a while and all these things may be related. Thanks for the ideas your coming back with, it's going to turn out to be something really silly in the end but finding it is proving to be hard going.

 

[zedonist]

Your pipe will come from the ICB on the 2.0.

If you've ruled out cable, and the throttle butterfly is not sticking, that only leaves the ICV as there is nothing after that to affect it, as long as there are no vacuum leaks or blocks

 

[kingsgate]

When I had the throttle body off I noticed that the pipe that the ICV fits into looks pretty new and seems a fairly tight fit, I think I'm chasing something that someone else was also trying to track down as many of the usual and obvious things seem either new or in good condition. I have squirted lots of carb cleaner around most of the engine, steered clear of the hot exhaust manifold, but have found nothing that has raised even half an eyebrow. I'm seriously considering removing and refitting the inlet manifold just to have a good look round and make sure all pipes etc are good. There are of course some small vacuum pipes on the rear of the cylinder head that are almost impossible to see or check without taking the manifold off but I did spray round the back there and got no response so assume all is well.

 

[zedonist]

Is the ICV working though?

 

[kingsgate]

Is the ICV working though?

As best I can tell yes it is. When I turn on the ignition it makes what I hope is a characteristic buzzing sound which stops once you start the engine. With the ICV unmounted but plugged in the port looks about half open and any attempt to change that position meets with resistance, also i get no EML or codes. Looking at OEMs diagrams the vacuum take off that I could see through the intake manifold aperture when the throttle body was off appears to go to the suction pump that operates the brake servo so I may investigat this further to see if the pipes in behind the manifold may be at fault, the suction pump doesn't leak I've sprayed that more than once and the brakes work okay.

 

[zedonist]

Well what i have just gleamed is that you share the same fuel prep system as the 2.5 engine i.e throttle body and icv, so you should be able to use the bentley manual for the 2.5 engine.

 

[kingsgate]

Okay thanks for that, it's really useful info as the manual costs a bob or two so maybe that's my next purchase on the quest.