Stuttering

[Marcusbimmer]

Help! Brand new Z4 M40i; had the dealer install LED door lights this weekend. Seemed to be fine after that. The next day (likely coincidence), during initial drive-away, there is a stuttering in the acceleration. Once I tapped the gas and it didn’t want to got then I did it again and it paused then went. Happened to my spouse today again. Scared her. It’s like a delay in gas pedal to acceleration. Anyone have any insight on this? Can the dealer remotely interrogate the ECU or do I have to drive 1.5 hours for this?

 

[Obs-Com]

Get to the dealership for diagnostic check as needs to be plugged in. Don’t think this can be done remotely. Not aware of any similar issues with the M40i. Hope it gets sorted and be helpful to give an update once you know.

 

[ori]

Call BMW assist from within the car. It’s unsafe to drive like that. They will send a guy over and he can plug it in and find fault. Your car will be repaired quicker that way too.

 

[ori]

Did you get to the bottom of this?

 

[Marcusbimmer]

So interesting.... Doesn't happen anymore. The ONLY thing that came to mind is that I filled the tank with PetroCan 94 gas at a station which normally probably doesn't sell a lot of 94 grade. That's the ONLY thing I can think of that was different. BUT, it didn't start until abou halfway into the tank so that doesn't make obvious sense either.

 

[ori]

Sounds like it was the fuel.

Only fill it with the good stuff!

 

[Z4monster]

Hey, has this problem gone away for you or has it happened again? I ask as mine has been doing this intermittently for a while. Feels like the first inch of travel isn't doing anything on the accelerator then if you persist it goes OK.
It's occurred a few times over several months but the car hasn't been getting driven that much recently. The fuel isn't the issue as this is new fuel this week and is from a reputable station.

It's going for oil service to BMW so they're going to check it out while they have it.

 

[Z4monster]

Hey, has this problem gone away for you or has it happened again? I ask as mine has been doing this intermittently for a while. Feels like the first inch of travel isn't doing anything on the accelerator then if you persist it goes OK.
It's occurred a few times over several months but the car hasn't been getting driven that much recently. The fuel isn't the issue as this is new fuel this week and is from a reputable station.

It's going for oil service to BMW so they're going to check it out while they have it.

UPDATE: Car went to local dealer last Friday and they had to keep it over the weekend. The car had logged faults with the throttle position sensor and they replaced it after getting parts Monday. Car is back in rude health again and all appears fixed. As it was an intermittent issue I hope they've managed to find the fault first time.

 

[Sladester100]

Ooh.

Apols’ for the old thread revival

Interesting…
Ive experienced this a few times. Each when it was cold and very soon after starting, I assumed initially as yo did that it was fuel related as coincidentally had used some cheap stuff from a local garage that had a reputation (found out afterwards typically).
My latter assumptions were engine temp related and I wondered if was somehow related to the computer protecting the engine when cold and reducing throttle response / revving but reading comments here that’s not really safe and unlikely to be “a feature” so perhaps I’ll book it in for a diagnostics.

Did you find the revs dipped slightly as one of the times I found that, and it almost seemed a bit “starved” hence considered dodgy fuel.

 

[Z4monster]

Ooh.

Apols’ for the old thread revival

Interesting…
Ive experienced this a few times. Each when it was cold and very soon after starting, I assumed initially as yo did that it was fuel related as coincidentally had used some cheap stuff from a local garage that had a reputation (found out afterwards typically).
My latter assumptions were engine temp related and I wondered if was somehow related to the computer protecting the engine when cold and reducing throttle response / revving but reading comments here that’s not really safe and unlikely to be “a feature” so perhaps I’ll book it in for a diagnostics.

Did you find the revs dipped slightly as one of the times I found that, and it almost seemed a bit “starved” hence considered dodgy fuel.

When mine does this it feels fuel starved for a second or two and then picks up OK. It only happens from a complete standstill. E.G. at the lights and doesn't have any issue when on the move. Pulls like a train as normal at full revs once moving. I've tried stopping and restarting the engine and even locking the car. Doesn't usually make any difference. Then it will suddenly stop doing it again and go back to normal behaviour. My car has definitely been up to full temp when it's done it so not just a cold start issue.

It went back to BMW again after they replaced the throttle position sensor. This time they found no faults and couldn't replicate it. Very annoying really.

It only does it occasionally and doesn't last long but does annoy me when it happens.

 

[motorknut]

Hi all, I was directed to this thread after seeking help on bimmerpost.

Throttle hesitation has been reported by Supra owners too. I’ve been wondering why I hadn’t seen any complaints online from z4 owners (till now).

My own unit is experiencing this intermittently. I also have an intermittent long crank start up issue, and I’m starting to suspect they are related.

From day 1, my car has had a long crank start up, around once every 2 months. Bimmerlink shows shadow codes pointing to HPFP and Low fuel pressure.

Late last year (about a year into ownership) the car started demonstrating a throttle hesitation.at first I thought it was my imagination cos it happens so momentarily, I would let off the gas, Wait. And try again, and it would be fine.

I realised it was not just my imagination when one day, I was stopped facing upwards on a slope, waiting to make a turn. I stepped on the gas and the car did not move (or roll back) but the rpms started bouncing and the engine sounded weird. I braked, waited a few seconds and Tried the gas and it was fine.

I have run a sensor log using bimmer link, and it shows that the fuel pressure fails to rise for the first 1-2 seconds that the accelerator is depressed. Then suddenly the pressure kicks in.

These are my observations:

• Hesitation occurs within about 500m of driving from start up.

• Time engine has run doesn’t seem to make a difference, as I’ve tried letting car warm up too. Still occurs.

• Not seemingly related to traction as roads always dry for my experiences.

• Power resumes after about 1-2 seconds without needing to depress the pedal much more

• Almost always occurs only once during a drive. Once, occured twice in one drive.

• Has occured twice in a single day, different drives.

• both cold or warm starts.

• both flat or on upwards inclines.

The feeling is like fuel starvation, and I wouldn’t expect rpms to bounce otherwise. I’m having to send my car back into Toyota, but previously they picked up nothing on their scan tool and it’s almost impossible to replicate it on demand. My guess is hpfp mechanical issues.. at least I hope it’s just that. A software fault would be impossible for Toyota to fix on their own. Before seeing this thread, I started to think it was a Toyota tuning issue

The throttle hesitation leaves no shadow codes when I check with bimmerlink. Only the long crank start up triggers hpfp and valvetronic threshold warnings (the latter is a new development)

 

[motorknut]

Ooh.

Apols’ for the old thread revival

Interesting…
Ive experienced this a few times. Each when it was cold and very soon after starting, I assumed initially as yo did that it was fuel related as coincidentally had used some cheap stuff from a local garage that had a reputation (found out afterwards typically).
My latter assumptions were engine temp related and I wondered if was somehow related to the computer protecting the engine when cold and reducing throttle response / revving but reading comments here that’s not really safe and unlikely to be “a feature” so perhaps I’ll book it in for a diagnostics.

Did you find the revs dipped slightly as one of the times I found that, and it almost seemed a bit “starved” hence considered dodgy fuel.

When mine does this it feels fuel starved for a second or two and then picks up OK. It only happens from a complete standstill. E.G. at the lights and doesn't have any issue when on the move. Pulls like a train as normal at full revs once moving. I've tried stopping and restarting the engine and even locking the car. Doesn't usually make any difference. Then it will suddenly stop doing it again and go back to normal behaviour. My car has definitely been up to full temp when it's done it so not just a cold start issue.

It went back to BMW again after they replaced the throttle position sensor. This time they found no faults and couldn't replicate it. Very annoying really.

It only does it occasionally and doesn't last long but does annoy me when it happens.

Don’t think it’s the throttle position sensor, cos I have the pedal angle tracked in my sensor log (for my Zupra) and it shows the pedal is depressed, but it’s the fuel pressure that doesn’t rise. In fact, it dips slightly below idle levels. This is for about 1.5-2 seconds, then pressure shoots up.

Have you had any luck since with the bmw dealer?

 

[BMWZ4MC]

I don’t know if there are any Supra forums in Aus, but it’s seems to be a very popular car here in Sydney (I usually see several in a week). It might be worth seeing if anyone has experienced the same problem.

 

[motorknut]

I don’t know if there are any Supra forums in Aus, but it’s seems to be a very popular car here in Sydney (I usually see several in a week). It might be worth seeing if anyone has experienced the same problem.

Thanks. There are a number of Aussie supra owners on the MK5 forum, but i didn’t notice any contributing on the throttle hesitation thread so far. Fair number of US owners reporting it.

 

[Z4monster]

Don’t think it’s the throttle position sensor, cos I have the pedal angle tracked in my sensor log (for my Zupra) and it shows the pedal is depressed, but it’s the fuel pressure that doesn’t rise. In fact, it dips slightly below idle levels. This is for about 1.5-2 seconds, then pressure shoots up.

Have you had any luck since with the bmw dealer?

It hasn't been back to BMW since my last visit. To be honest I was pretty annoyed with them. Their attitude was 'We can't see a computer fault so we can't diagnose the issue unless it's occurring when we have the car' Also 'Can you not bring it in when it's happening?'
Err, it's intermittent and I could be 30 miles form you when it happens. Also it could stop doing it on the way to you, so the answer is NO! I can see their point but less than great customer service IMO.

Unless it throws a dash fault then I'm basically stuck with it happening from time to time.

Interestingly, it seems to happen less with higher octane fuel onboard although that could be completely coincidental. Next month I'm back in the office again so the car will be getting more usage. Let's see if it starts occurring more frequently. If it does, BMW will be getting the car until they find the fault.

 

[motorknut]

It hasn't been back to BMW since my last visit. To be honest I was pretty annoyed with them. Their attitude was 'We can't see a computer fault so we can't diagnose the issue unless it's occurring when we have the car' Also 'Can you not bring it in when it's happening?'
Err, it's intermittent and I could be 30 miles form you when it happens. Also it could stop doing it on the way to you, so the answer is NO! I can see their point but less than great customer service IMO.

Unless it throws a dash fault then I'm basically stuck with it happening from time to time.

Interestingly, it seems to happen less with higher octane fuel onboard although that could be completely coincidental. Next month I'm back in the office again so the car will be getting more usage. Let's see if it starts occurring more frequently. If it does, BMW will be getting the car until they find the fault.

I’ve been running premium 98 octane gas in my Zupra since day 1, and this hesitation only started about 15 months into ownership. Coincidentally, after I had the brake safety recall work done.

The dealers always try to replicate the fault before they proceed with repairs, but intermittent faults are a pain. What I’ve done is provided evidence like dash cam footage and the sensor reading logs from BimmerLink.

Have you considered running a BimmerLink with an OBDlink reader to observe readings when you’re driving? I also picked up the shadow HPFP codes with BimmerLink - but those were triggered by long crank start ups. The hesitation doesn’t trigger any noticeable codes, shadow or otherwise.

 

[BrianD]

I've had the same issue with a flat spot/hesitation when either pulling away from a stationary position or when almost stopping then acelerating away since the end of November last year. This only appeared to happen after my dealer had updated the software, and have been through is it the petrol or a sensor scenario. I decided to book the car in with my dealer last Friday. As expected there were no error codes logged and the technician wasn't able to replicate the hessitation either. Obviosly it must be a known issue as they did mention that the delayed / sluggish response is a fault caused by incorrect application valve timing in the DSC, and they are not able to fix the fault until software is available in July 2022. Hopefully, this will fix the hessitation issue that I am experiencing, and it's not something that I have yet to notice!

 

[motorknut]

I've had the same issue with a flat spot/hesitation when either pulling away from a stationary position or when almost stopping then acelerating away since the end of November last year. This only appeared to happen after my dealer had updated the software, and have been through is it the petrol or a sensor scenario. I decided to book the car in with my dealer last Friday. As expected there were no error codes logged and the technician wasn't able to replicate the hessitation either. Obviosly it must be a known issue as they did mention that the delayed / sluggish response is a fault caused by incorrect application valve timing in the DSC, and they are not able to fix the fault until software is available in July 2022. Hopefully, this will fix the hessitation issue that I am experiencing, and it's not something that I have yet to notice!

You mention you had a software update - is this the safety brake recall? The throttle hesitation started in my car after the safety brake recall work, too. But my long crank start up issue was there from day 1.

I have been trying to ask my local Toyota dealer to check with HQ on any potential fault that BMW is working on, but they don’t seem to have any such info. They have agreed to change the HPFP on my car to try, since the long crank start up throws a HPFP low pressure shadow code on my BimmerLink app, and low fuel pressure is observed on the sensor readings I took during these occurrences. But this piece of info on a known dsc/valve issue makes me wonder.

Does anyone else have a long crank start up issue too?

 

[Sladester100]

Hi all, I was directed to this thread after seeking help on bimmerpost.

….

These are my observations:

• Hesitation occurs within about 500m of driving from start up.

• Time engine has run doesn’t seem to make a difference, as I’ve tried letting car warm up too. Still occurs.

• Not seemingly related to traction as roads always dry for my experiences.

• Power resumes after about 1-2 seconds without needing to depress the pedal much more

• Almost always occurs only once during a drive. Once, occured twice in one drive.

• Has occured twice in a single day, different drives.

• both cold or warm starts.

• both flat or on upwards inclines.

The feeling is like fuel starvation, and I wouldn’t expect rpms to bounce otherwise. I’m having to send my car back into Toyota, but previously they picked up nothing on their scan tool and it’s almost impossible to replicate it on demand. My guess is hpfp mechanical issues.. at least I hope it’s just that. A software fault would be impossible for Toyota to fix on their own. Before seeing this thread, I started to think it was a Toyota tuning issue

The throttle hesitation leaves no shadow codes when I check with bimmerlink. Only the long crank start up triggers hpfp and valvetronic threshold warnings (the latter is a new development)

This is exactly what I’ve observed, brilliant description!

No long crank start issue on mine

 

[motorknut]

I've had the same issue with a flat spot/hesitation when either pulling away from a stationary position or when almost stopping then acelerating away since the end of November last year. This only appeared to happen after my dealer had updated the software, and have been through is it the petrol or a sensor scenario. I decided to book the car in with my dealer last Friday. As expected there were no error codes logged and the technician wasn't able to replicate the hessitation either. Obviosly it must be a known issue as they did mention that the delayed / sluggish response is a fault caused by incorrect application valve timing in the DSC, and they are not able to fix the fault until software is available in July 2022. Hopefully, this will fix the hessitation issue that I am experiencing, and it's not something that I have yet to notice!

Interestingly enough, my car has been with my local Toyota dealer. They finally opened a case with HQ, and just informed me that after performing a series of tests on the car, they do not believe the fault to be mechanical in nature. They are advising for a software solution , and this is expected for September. Seems to make sense, alongside the bmw update expected for July.

Thing that pisses me off is that likely, Toyota knew of this issue and has not communicated the warning to the dealer network or owners. Maybe it’s cos not all cars are suffering this glitch.