Misfire
- Thread starter Animal
- Start date
always had this, always commented on it, no one seems to care really & to be honest I've done over 50k in mine & it's not changed a bit.
It's definitely less noticeable with sustained 99 Ron fuel, but sod that with the prices at the moment.
It's a characteristic of the engine to me - it's a pause as the VANOS moves or something I believe, although someone will probably correct me.
It's definitely less noticeable with sustained 99 Ron fuel, but sod that with the prices at the moment.
It's a characteristic of the engine to me - it's a pause as the VANOS moves or something I believe, although someone will probably correct me.
My stutter on 95 ron fuel is at or around 2k rpm. But that seems to be the same whether the engine is hot or cold. If its because i i'm using a lower grade fuel i can live with that.
But the kangarooing when cold seems to be something different and something i'd like to fix. Did the Z4M really do it from new? There must have been owners taking their car's back under the OEM warranty for it.
But the kangarooing when cold seems to be something different and something i'd like to fix. Did the Z4M really do it from new? There must have been owners taking their car's back under the OEM warranty for it.
I am not buying a £45k car to put cheap fuel in it.
As a comparison - my dad had an Audi which also had 98 as the preferred fuel, he ran it for 4 years no prob. Within months of selling it, the new owner had been using 95 and he started to have no end of fuel related issues. Coincidence? Perhaps, but for the few pounds difference I am not risking potential expensive repairs.
As a comparison - my dad had an Audi which also had 98 as the preferred fuel, he ran it for 4 years no prob. Within months of selling it, the new owner had been using 95 and he started to have no end of fuel related issues. Coincidence? Perhaps, but for the few pounds difference I am not risking potential expensive repairs.
I don't think it's so unusual to have a big, highly tuned engine being lumpy/jerky when cold.
Flat spots when warm aren't good though; I'd try V Power for a good few tanks and see what that's like, or possibly look at an Evolve remap that I'd lay money (around £400 I think :wink: ) that would sort it.
Flat spots when warm aren't good though; I'd try V Power for a good few tanks and see what that's like, or possibly look at an Evolve remap that I'd lay money (around £400 I think :wink: ) that would sort it.
If BMW specify that the car can run without problems on 95 ron fuel, as they do, then it should run on 95 ron fuel without problems. Whether it is a £45k car or a 10k car is irrelevant.
If putting 97/8 Ron fuel masks the problem, the problem is still there. If the problem is still there you are probably still losing performance even with 97/8 Ron fuel.
The risk you run with using a lower ron fuel is det if the ignition is too advanced. As we have a knock sensor and the ECU is constantly working to maintain the optimum timing for the fuel you are using the ECU will retard the ignition if you use a lower Ron fuel.
Secondly, you don't get det at light, low load throttle openings which is exactly when i get the stutter.
My previous Honda S2000 produces more BHP per litre than the Z4M yet runs quite happily on 95 Ron fuel and from cold. I don't agree with the school of thought that says that modern highly tuned engines are allowed to run badly when cold or on 95 Ron fuel.
I am by no means suggesting that the S2000 is a better car. It isn't, hence why i bought the Z4M. But this stutter and the lumpy running when cold doesn't seem right to me.
If putting 97/8 Ron fuel masks the problem, the problem is still there. If the problem is still there you are probably still losing performance even with 97/8 Ron fuel.
The risk you run with using a lower ron fuel is det if the ignition is too advanced. As we have a knock sensor and the ECU is constantly working to maintain the optimum timing for the fuel you are using the ECU will retard the ignition if you use a lower Ron fuel.
Secondly, you don't get det at light, low load throttle openings which is exactly when i get the stutter.
My previous Honda S2000 produces more BHP per litre than the Z4M yet runs quite happily on 95 Ron fuel and from cold. I don't agree with the school of thought that says that modern highly tuned engines are allowed to run badly when cold or on 95 Ron fuel.
I am by no means suggesting that the S2000 is a better car. It isn't, hence why i bought the Z4M. But this stutter and the lumpy running when cold doesn't seem right to me.
Might want to reset the throttle too, but it will take more than one tank full through before the engine adapts to the higher grade fuel & it runs smoother.
I'll remap mine this year & see if it's still there but I expect it to be, with respect to 98/95 I still only ever use good fuel - usually Shell (airmiles too..) and you can definitely tell when you have a crap tank. But I worked out recently my Z4M 50+k experience has cost me around £24,000 in fuel alone, so it'll only get the 98 on special occasions for a bit now.
To me the 'flatspot' is usually predictable too, if I'm decelerating in traffic say 1k rpm in 3rd then want a speedy takeoff, how much fun is it to head to 7k in 2nd gear instead?
I'll remap mine this year & see if it's still there but I expect it to be, with respect to 98/95 I still only ever use good fuel - usually Shell (airmiles too..) and you can definitely tell when you have a crap tank. But I worked out recently my Z4M 50+k experience has cost me around £24,000 in fuel alone, so it'll only get the 98 on special occasions for a bit now.
To me the 'flatspot' is usually predictable too, if I'm decelerating in traffic say 1k rpm in 3rd then want a speedy takeoff, how much fun is it to head to 7k in 2nd gear instead?
I fully agree. I certainly wouldn't expect it to run produce as much power or give the same throttle response on 95Ron fuel as i would on the optimal 97/8.pvr said:
But i do expect it to run smoothly.
Same with a PC. You'd expect the software to run, albeit with lower performance. You wouldn't expect it to keep crashing to freezing if it met the minimum design spec.
Andy said:Might want to reset the throttle too, but it will take more than one tank full through before the engine adapts to the higher grade fuel & it runs smoother.
I'll remap mine this year & see if it's still there but I expect it to be, with respect to 98/95 I still only ever use good fuel - usually Shell (airmiles too..) and you can definitely tell when you have a crap tank. But I worked out recently my Z4M 50+k experience has cost me around £24,000 in fuel alone, so it'll only get the 98 on special occasions for a bit now.
To me the 'flatspot' is usually predictable too, if I'm decelerating in traffic say 1k rpm in 3rd then want a speedy takeoff, how much fun is it to head to 7k in 2nd gear instead?
I'm going to try the throttle reset tonight.
I notice the stutter most when driving in traffic. Most of my 16 mile commute is on reasonably fast country roads but i have an urban trundle when i get near to my factory. So flooring to the redline in second isn't normally an option at that point
Throttle reset has made no difference to the flat spot/ stutter. It is less noticeable now that its running on V-power but still there. V-power hasn't helped the lumpy running from cold problem either.
I'd really love to know what's causing this. Next thing is to check and clean the MAF.
I'd really love to know what's causing this. Next thing is to check and clean the MAF.
Reading around the subject on the m3 cutters site it appears that cleaning the MAF is risky. I'm going to have to order a new one.
I also need to reset the fuel trims when the MAF is replaced. Does anyone know if that can be done without the use of a scangauge or similar diagnostic tool, ie by pulling a fuse to remove power to the ecu?
I also need to reset the fuel trims when the MAF is replaced. Does anyone know if that can be done without the use of a scangauge or similar diagnostic tool, ie by pulling a fuse to remove power to the ecu?
I hadn't read that thread, but i have now
It seems that cleaning the MAF can be hit or miss. Some say don't use alcohol as it can damage the sensor. Some say don't touch the sensor with anything other than electrical contact cleaning solvent. There doesn't seem to be any definitive information over what is the correct way to clean it without damaging it.
However, a new sensor is only £150 and as my car is my daily driver i'm inclined to bite the bullet and just pay for a new sensor rather than risk damaging the sensor whilst attempting to clean it and then not be able to drive my car whilst i wait for a replacement.
It seems that cleaning the MAF can be hit or miss. Some say don't use alcohol as it can damage the sensor. Some say don't touch the sensor with anything other than electrical contact cleaning solvent. There doesn't seem to be any definitive information over what is the correct way to clean it without damaging it.
However, a new sensor is only £150 and as my car is my daily driver i'm inclined to bite the bullet and just pay for a new sensor rather than risk damaging the sensor whilst attempting to clean it and then not be able to drive my car whilst i wait for a replacement.
Having said i wouldn't risk cleaning the MAF i then found out i could use my wife's car for the next few days if required if cleaning the MAF damaged it and i needed a new one.
I bought some Halford's electical contact cleaner which other people had used successfully and appears to consist of isopropyl alcohol and naptha (ie the same as the CRC contact cleaner available in the states). I removed the MAF, let it cool down to room temperature for an hour or two and then liberally sprayed the appropriate parts with the contact cleaner. I did not touch any of the sensing parts (ie the 'window' or the temperature sensor) with anything other than the spray of solvent from the car. They are very sensitive to damage so i was relying on the solvent spray washing away any contaminants rather using a brush or cotton bud etc. I then let it dry for an hour or so until all traces of the cleaner had evaporated and refitted it to the car.
Car started as normal and the 2k stutter that was annoying me so much has completely vanished. Then when I started the car this morning the rough running that it had been suffering from for about 60 seconds from cold had virtually gone.
I am very, very pleased. The 2k stutter had been really bugging me and is just not something that i expect or would tolerate from a 3 year old, 13k miles car that cost in excess of £45k new.
However, i have no idea if i've affected the longevity of the MAF so i would only suggest cleaning the MAF and risking damaging it if you have access to another vehicle whilst you wait for a new MAF to be delivered.
I bought some Halford's electical contact cleaner which other people had used successfully and appears to consist of isopropyl alcohol and naptha (ie the same as the CRC contact cleaner available in the states). I removed the MAF, let it cool down to room temperature for an hour or two and then liberally sprayed the appropriate parts with the contact cleaner. I did not touch any of the sensing parts (ie the 'window' or the temperature sensor) with anything other than the spray of solvent from the car. They are very sensitive to damage so i was relying on the solvent spray washing away any contaminants rather using a brush or cotton bud etc. I then let it dry for an hour or so until all traces of the cleaner had evaporated and refitted it to the car.
Car started as normal and the 2k stutter that was annoying me so much has completely vanished. Then when I started the car this morning the rough running that it had been suffering from for about 60 seconds from cold had virtually gone.
I am very, very pleased. The 2k stutter had been really bugging me and is just not something that i expect or would tolerate from a 3 year old, 13k miles car that cost in excess of £45k new.
However, i have no idea if i've affected the longevity of the MAF so i would only suggest cleaning the MAF and risking damaging it if you have access to another vehicle whilst you wait for a new MAF to be delivered.
I've now been used the car a bit and i'm pleased to report cleaning the MAF has completely fixed the 2k stutter. The engine feels much more responsive and the 2k flat spot has vanished. That is on both V-power and normal shell 95.
However, the lumpy running when starting from cold is still present and unchanged. When its really cold the engine starts and runs perfectly. When the engine is warm it starts and runs perfectly. However, when the car is started having stood outside on the drive all night and the temperature is around 8-10 degrees C it starts and idles perfectly but kangaroos a bit for the first 30 seconds or so of driving.
Has anyone got any ideas on what to look at next?
However, the lumpy running when starting from cold is still present and unchanged. When its really cold the engine starts and runs perfectly. When the engine is warm it starts and runs perfectly. However, when the car is started having stood outside on the drive all night and the temperature is around 8-10 degrees C it starts and idles perfectly but kangaroos a bit for the first 30 seconds or so of driving.
Has anyone got any ideas on what to look at next?