Sudden loss of throttle response

[overthehills]

After almost 4 years of great reliability from the old girl ('02 Z3 2.2i) I've finally had to call the RAC to get me out of a fix.

Pulled up in a car park and once I'd engaged the handbrake, noticed a lack of throttle response. Switched her on and off a few times and concluded that she starts totally normally and idles smoothly as ever. It's just that the throttle seems... Like it's totally disconnected.

She cut out briefly twice yesterday, too, but on both occasions I could use idle (well, sub-2000 rpm) to maneouvre to a safe place, and she was subsequently good to get me the 3 or 4 miles I needed.

Any quick thoughts while I await the orange mechanic?

 

[mrscalex]

Get the codes read and report back first of all.

I had a similar failure like that though. I needed a new throttle body. I suspect the throttle was getting stuck then freeing off. Drove nicer than before the issue with the new part as well. I got lucky and found a new BMW part cheap.

 

[t-tony]

On the fly by wire system the pedal itself could also by suspect. We changed few of these on various makes over the years including several Ford Transit tyre trucks.

Tony.

 

[overthehills]

Cheers chaps. I'll see what the RAC mech can do when they get here. Will the OBD2 under the wheel be enough or do I need to direct them somewhere under the bonnet?

As an aside I'm in Penzance at present should any of our fellow members be in and around west Cornwall. Seen a few Zeds about!

 

[t-tony]

The under dash connector should give access to engine related issues as far as I’m aware. A good mobile tec h ought to know that though.

Tony.

 

[overthehills]

Funny you say "good mobile tech" as the RAC have just called to advise they've no local patrols, so some random firm will shortly assist

Feel like it's going to be a long evening.

 

[backseateducation]

I hope they don't make you wait too long. I'm near St Austell but I'm not much good as a mechanic and I've got electrical problems of my own!

 

[t-tony]

Funny you say "good mobile tech" as the RAC have just called to advise they've no local patrols, so some random firm will shortly assist

Feel like it's going to be a long evening.

Hopefully you will get a man, or woman who knows what they're doing. Good luck.

Tony.

 

[overthehills]

Cheers again, both.

Interestingly I just started her up (twice) and on both occasions the throttle functioned properly. I guess that whatever is going on, the linkage still exists and the positioning is still detected reasonably accurately.

I'll see what the recovery firm advise and report back. If nothing else, something else for the knowledge base perhaps!

 

[overthehills]

Update!

Against all logic, she seems to have rediscovered throttle response. I called the 3rd party recovery firm and when they advised a 3 hour wait, we mutually agreed I should attempt the 2 mile drive to my temporary digs.

Made it back ok with no issues. So recovery firm stood down. Will get a code reader on the case tomorrow and see where we are.

What's our collective thoughts on intermittent loss of throttle response, generally in first gear and at low revs?

 

[t-tony]

Any DSC lights showing or recently been on?

Tony.

 

[overthehills]

Any DSC lights showing or recently been on?

Tony.

Nope. I think DSC kicked in a week or so ago but that's as I was a bit over-eager to circulate a damp roundabout. Nothing untoward there (driver aside!).

 

[Andyboy]

I've had this on both the M52TU and M54 where the throttle disc has started to stick. Removing the intake rubber boot, opening the throttle disc by hand and cleaning the throttle body with brake cleaner and very fine emery (1000 grit) fixed it. It's the steel disc wearing a slight ridge in the alloy that does it, combined with a build up of intake 'gunge'.

But, reading the fault codes is a given.

 

[mrscalex]

I've had this on both the M52TU and M54 where the throttle disc has started to stick. Removing the intake rubber boot, opening the throttle disc by hand and cleaning the throttle body with brake cleaner and very fine emery (1000 grit) fixed it. It's the steel disc wearing a slight ridge in the alloy that does it, combined with a build up of intake 'gunge'.

But, reading the fault codes is a given.

That's what I presume happened with mine. But I had the chance for a very cheap new BMW part off ebay so went with that instead.

From memory the only errors I had triggered were ABS (DCS) errors. Again, I presumed, because the DSC wants to be able to take control of the throttle if required and was not getting the right feedback to assure itself of this.

 

[overthehills]

Another update. Plugged a generic (Carly) OBD2 reader in, cleared the existing faults and left the car running while stationary. Note that this morning she starts, idles and runs as she has done since a major service about 7 months previous - no issues with the throttle.

Three faults logged: P0100, P0102 and C0700.

See attached for the code breakdown.

Prior to clearing historic faults were references to camshaft position sensors and misfires, although I've not checked any faults since aforementioned service so these could well have been resolved. Can add screenshots if the attached sheds no light.

Thoughts?!

Cheers in advance.

 

[motco]

Mine stopped responding to the throttle (2.2i fly by wire) showed engine light and DSC lights. Idled alright but wouldn't rev. It was as others have suggested, a sticky throttle body butterfly. A second hand throttle body from eBay and we were back on the road.

 

[mrscalex]

Another update. Plugged a generic (Carly) OBD2 reader in, cleared the existing faults and left the car running while stationary. Note that this morning she starts, idles and runs as she has done since a major service about 7 months previous - no issues with the throttle.

Three faults logged: P0100, P0102 and C0700.

See attached for the code breakdown.

Prior to clearing historic faults were references to camshaft position sensors and misfires, although I've not checked any faults since aforementioned service so these could well have been resolved. Can add screenshots if the attached sheds no light.

Thoughts?!

Cheers in advance.

Did you make a note of the existing codes before clearing? You've not necessarily picked up the root error of the breakdown issue here from telling us faults after clearing codes.

I'm not great on generic codes. BMW codes will be much better known on here but will require a specific reader. Those descriptions could be generic terminology for the root issue elsewhere or you may have an incidental/additional error with the MAF.

What you had sounds a little drastic for the MAF. And probably for the other thing I'd consider which is the inlet camshaft sensor. Those faults also tend to stick around once they are there. A sticking throttle issue would come and go.

 

[overthehills]

Yep - didn't dare consign the codes to history! Here's the full log before clearing (7 "confirmed", 2 "pending"). Note that a misfire was identified and fixed at the service so may be a red herring.

Don't have access to a BMW code reader.

Attached: 3 screenshots.

 

[Althulas]

I’m working down in Cornwall at the moment and staying In Camborne. I have my Creator C130 in the boot so if you have any further problems in the near future give me shout.

 

[overthehills]

A brief update for those of you following this thread or struck dumb by similar symptoms of your own, now I've got some miles logged.

Got her to a local garage (Crowlas area) where, after much digging around and diagnostics, a brand new MAF was fitted. This led to smoother running and no cut outs, but the cam position sensor fault returned.

So I nipped down to Euro Car Parts and nabbed a mid-market cam position sensor and fitted that (hat tip to my brother and his handy toolkit).

Have driven about 500 miles since, over 3 or 4 weeks, and no fault codes at all. In fact, she runs smoother than she did before the summer and I'm perhaps even seeing an extra 1 or 2 mpg. That or Momentum 99 is substantially better than V-Power

So hopefully that's that. No thanks to the orange recovery service, who ultimately weren't any use whatsoever!

Thanks again to all of you who helped and generally commiserated.