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Lazy, Jerky, Horrible Throttle

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nichollsz4
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Lazy, Jerky, Horrible Throttle

Post by nichollsz4 » Tue Aug 29, 2017 7:51 pm

Hello fellow Z4m owners,

I've started a thread to see if anyone has had any issues, as titled above, that might be similar to what I'm currently going through.

I've had my Z4m for a little over a month now and other than the usual niggles, it's been fine. I have however noticed a lazy throttle response and horrendous jerk when changing gear. (Like dumping the clutch) its just impossible to drive smoothly. In fact, it drives better when cold!

Diagnostics shows error codes for MAF sensor and throttle body sensor, but I have unplugged them and cleaned them down.

I'm booking the car back in the garage to be looked at further, but I'm just wondering if anyone else had a similar problem and what the fix was?

Thanks,

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Argenta
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Post by Argenta » Tue Aug 29, 2017 9:00 pm

Tried resetting the throttle?
Easy,
10sec ign on
10s ign off
10s ign on
Start engine
Turn off.
(Never touch pedals)

I have to do this once a month or so.. Funny little car this!

nichollsz4
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Post by nichollsz4 » Wed Aug 30, 2017 4:08 pm

Haven't tried this yet. How long do I leave the engine running for before turning off?

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Post by TomK » Wed Aug 30, 2017 4:15 pm

Argenta wrote: Tue Aug 29, 2017 9:00 pm Tried resetting the throttle?
Easy,
10sec ign on
10s ign off
10s ign on
Start engine
Turn off.
(Never touch pedals)

I have to do this once a month or so.. Funny little car this!
I've never had to do this with mine nor AFAIK has my pal with another, so I'd suggest there's something amiss with yours.
nichollsz4 wrote: Wed Aug 30, 2017 4:08 pm Haven't tried this yet. How long do I leave the engine running for before turning off?
You don't need to run the engine before doing this, just follow his instructions when you go to start the car.
Eta sorry misunderstood your post. You do not need to run the engine for any length of time after doing this, the reset command happens before you start the engine.
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Fishy Dave
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Post by Fishy Dave » Wed Aug 30, 2017 4:48 pm

nichollsz4 wrote: Tue Aug 29, 2017 7:51 pm
Diagnostics shows error codes for MAF sensor and throttle body sensor, but I have unplugged them and cleaned them down.
Is their a local member you could try swapping these parts with? If not then the error codes are probably right and you'll need to buy new ones.
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Argenta
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Post by Argenta » Wed Aug 30, 2017 5:23 pm

Sorry thats right, you don't actually need to start.

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Post by Pures3 » Wed Aug 30, 2017 11:24 pm

Could it be the clutch delay valve?

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Post by AndyBeech » Thu Aug 31, 2017 2:26 pm

Pures3 wrote: Wed Aug 30, 2017 11:24 pm Could it be the clutch delay valve?
CDV isn't really noticeable TBH so no not with the symptoms described.

With what you've said, it sounds like the throttle body valves are shutting off which does give a nasty jerk like the clutch dumping or a fuel cut type feel, although not sure why it would be when changing gear, might be coincidence?

Does point to an issue with potentially the TP sensors though, if they read incorrectly or one doesn't match up with the other (one on the throttle actuator and one on the throttle valve 'bar') then it could lead to it shutting off suddenly to protect the engine at certain throttle / rpm situations, hence the jerk. Also would give poor throttle response as described.
I would say look at the TP sensors first. Cheapest and easiest fix, and if they've never been changed is well worth doing anyway and then go from there.
Also, what diagnostics are you using?
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Post by TomK » Thu Aug 31, 2017 2:39 pm

One of the tps sensors or possibly the throttle actuator would be my first thought.
The maf may also be the culprit, cleaning it won't necessarily help. Try unplugging the maf and see how it runs (it should run fine-ish without it), if that resolves it somewhat then maf will need replacing.
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Post by Fishy Dave » Thu Aug 31, 2017 2:45 pm

AndyBeech wrote: Thu Aug 31, 2017 2:26 pm Does point to an issue with potentially the TP sensors though
Agreed, although only slightly similar symptoms to what I experienced when my front TPS went down. The main thing I noticed was a lack of willingness to rev, plus the warning light with the specific TPS failure code.
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Post by Sam1977 » Thu Aug 31, 2017 3:31 pm

Hi my car is going to BMW Carteya in Algeciras on Monday as I have a slight problem at idle revs when I go to drive off the revs dip slightly when I apply light throttle making it very easy to stall. These cars seem to suffer from an issue that doesn't affect the equivalent M3. I have no CEL and no codes so its not clear enough to me to be able to diagnose adequately. Loads of threads around on it but nothing conclusive anywhere unfortunately so rather than follow the common parts replacement and cleaning and see if it works I am just going to take it to BMW and tell them to sort it out!! I would imagine the possibilities are ICV, TPS, lambda sensor, fuel filter, vacuum leak or something like that. Going to have a few blemishes on paint sorted out at the same time. I'll let you know what they do to mine.

Just to try and relate my issue back to yours, its not identical - mine only has an issue with a rev dip from idle, beyond 1000rpm I have no hesitation or any other issue. But that's not to say mine isn't an issue that could progress into something worse if not resolved.
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nichollsz4
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Post by nichollsz4 » Fri Sep 01, 2017 10:25 pm

Apologies for the delay responding. Its been a long week.

Bit of an update...

The car was diagnosed with a Snap on diagnostics device. I have been driving since clearing the faults from my initial post for over a week now and there has been no change in the car. It has been plugged back in today and no faults were found It has also been plugged into BMW diagnostics which also found no faults. The other faults found previously were a result of me unplugging things whilst the car was running. (miss diagnosis)

Whilst plugged in, the throttle body sensor was tested, which found no problems and something specific (forget what the tech called it) was reset relating to throttle position, etc. checked idle and smooth running and all looked good.

The only thing that the tech did say that he wasn't get a good reading from the throttle sensor, but it was clearly working. If the TS was on the blink, its more than likely a fault would register.

Looking at whats been checked and with no fault codes to go off, I can only surmise that the issue may be a result of a bad MAF sensor. BMW of this period were terrible for MAF sensors being end of life, and the ECU failing to flag it. I have actually unplugged the MAF for now to see what changes I get. So far nothing has changed. I expect to see the EML to pop up as I continue to use the car and will be interesting to see how the car changes, if at all.

Question, there is a 'secret' menu you can access from on the cluster where you can bring up the MAF sensor. Form here you can see the MAF sensor reading which i'm told shouldn't drop below a certain number. Does anyone know the process to access the menu and the figure the MAF sensor shouldn't drop below?

Thanks,

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Post by srhutch » Fri Sep 01, 2017 11:30 pm

Sam1977 wrote: Thu Aug 31, 2017 3:31 pm Hi my car is going to BMW Carteya in Algeciras on Monday as I have a slight problem at idle revs when I go to drive off the revs dip slightly when I apply light throttle making it very easy to stall. These cars seem to suffer from an issue that doesn't affect the equivalent M3. I have no CEL and no codes so its not clear enough to me to be able to diagnose adequately. Loads of threads around on it but nothing conclusive anywhere unfortunately so rather than follow the common parts replacement and cleaning and see if it works I am just going to take it to BMW and tell them to sort it out!! I would imagine the possibilities are ICV, TPS, lambda sensor, fuel filter, vacuum leak or something like that. Going to have a few blemishes on paint sorted out at the same time. I'll let you know what they do to mine.

Just to try and relate my issue back to yours, its not identical - mine only has an issue with a rev dip from idle, beyond 1000rpm I have no hesitation or any other issue. But that's not to say mine isn't an issue that could progress into something worse if not resolved.
Is this under warranty?
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Sam1977
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Post by Sam1977 » Sat Sep 02, 2017 2:09 am

No its not under warranty, I have to pay them.
BMW Z4M INTERLAGOS BLUE
Other tin:
Porsche 911 Turbo S / Boxster S
BMW E60 M5 / E38 740i / E46 320d / E36 316i / E46 330Ci (Time Attack car)
Mercedes SL500
Hyundai Accent Copa (Andalucia Cup) x3
Audi A6 Avant x2
Nissan Navara
Fiat Punto Sporting

nichollsz4
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Post by nichollsz4 » Sat Sep 02, 2017 7:23 am

Sam1977 wrote: Thu Aug 31, 2017 3:31 pm Hi my car is going to BMW Carteya in Algeciras on Monday as I have a slight problem at idle revs when I go to drive off the revs dip slightly when I apply light throttle making it very easy to stall. These cars seem to suffer from an issue that doesn't affect the equivalent M3. I have no CEL and no codes so its not clear enough to me to be able to diagnose adequately. Loads of threads around on it but nothing conclusive anywhere unfortunately so rather than follow the common parts replacement and cleaning and see if it works I am just going to take it to BMW and tell them to sort it out!! I would imagine the possibilities are ICV, TPS, lambda sensor, fuel filter, vacuum leak or something like that. Going to have a few blemishes on paint sorted out at the same time. I'll let you know what they do to mine.

Just to try and relate my issue back to yours, its not identical - mine only has an issue with a rev dip from idle, beyond 1000rpm I have no hesitation or any other issue. But that's not to say mine isn't an issue that could progress into something worse if not resolved.
Hi Sam,

My car isn't easy to stall, and I haven't paid much attention to where the revs dip. I'm usually changing gear between 2-3k but notice it allot smoother when changing lower than 2k

I'm starting with a new MAF, which I'd be tempted to do in your position too. My understanding is the ECU works out the correct fuel and air mixture demand from the sensors. So imagine if that sensor was tired and giving the wrong information such as providing lower air than what's required. Your MAF could be giving false reading that will cause your car to want to stall.

This my understanding, so might be wildly inaccurate. Appreciate you just wanting it fixing, but with no codes like yourself, all that BMW will do is troubleshoot further. With no warranty, that could be a heavy bill.

I'm running mine with the MAF unplugged, so will let you know of any changes/developments.

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