Part throttle hesitation during data logging

[MBan]

Hi all,

I am hoping for a bit of trouble shooting help for an issue I noticed when doing some data logging in my Z4M.

When doing a third gear, partial throttle run (35-37% on the TPS signal) I noticed a couple of hesitations, one around 5,500rpm and another at around 6,200rpm. In the data logs I can’t really make out the 5,000rpm hesitation but the one at 6,200 rpm shows up as a dip and then a little spike in load, AFR and lambda integrator 1 and 2. The TPS signal doesn’t show a dip but does jump a little at the end of the ‘event’, while the MAF signal may also jump a bit but it is hard to tell with the relatively noisy signal. VANOS and ignition timing don’t show anything unusual at those rpms. No error codes have come up.

Spark plugs were changed around 2,000 km ago but coils have not been changed as far as I am aware. The car is completely stock at the moment.

Any suggestions on what could be the cause?

I am having Supersprint V1 stepped headers and cat’d section 1 installed early in the new year and will be getting a tune at the same time, so would like to get on top of any gremlins beforehand if possible.

Thanks in advance.

[maupineda]

I would do a throttle body, ICV, and MAF cleaning. I would also have a look at the spark plugs just for visual inspection. When was the last time you had the injectors serviced? Mileage on the car? To sum up, I’d start with a tune up.

[MBan]

Thanks, Maupineda.

The car has 32,000km on it and to the best of my knowledge has never had the injectors serviced.

I have been thinking about doing a clean of the throttle body, ICV and MAF, as you suggest. I'll try to get that done ASAP.

[maupineda]

With that mileage, i would skip injectors, and only do the items mentioned.

[MBan]

What are your thoughts on coils? Could that be a potential source?

[maupineda]

Originally Posted by MBan

What are your thoughts on coils? Could that be a potential source?

Hard to tell without proper diagnostic software to see of there are misfires at certain cylinders so you could swap them and see if the misfire follows it. Your mileage is really low, but also time ages things, so is a possibility. But without diagnosis you may be just throwing parts at it.

[MBan]

Originally Posted by maupineda

Hard to tell without proper diagnostic software to see of there are misfires at certain cylinders so you could swap them and see if the misfire follows it. Your mileage is really low, but also time ages things, so is a possibility. But without diagnosis you may be just throwing parts at it.

Thanks, maupineda. I'll leave the coils for the moment and do the throttle body and ICV cleaning and TPS replacement.