I've been having an issue when first pulling away on cold starts and wanted to know if anyone else has had this.
When I first let off the brake and let the car creep forwards the revs will dip a lot and the car labours for a second before pulling away normally, it feels close to stalling sometimes. I've linked to a log of the behaviour with a marker placed where the drive-off occurs. It will keep doing this to a lesser degree for the first couple of minutes of driving then after that it's absolutely fine.
It only happens when the engine is cold on the first start of the day. Outside temps here are about 5-10C so not anything crazy cold.
Some things I've already considered and ruled out:
DCT software: Does it with the latest Z4 35i software and also the 35is software.
DCT Adaptions: I ran through all the adaption routines in ISTA following all instructions and there's no change
Fluid leak: Transmission has no leaks, the sump and gasket were replaced by BMW 1 year ago with fresh fluid.
Parking brake sticking: Does it even when car is left without parking brake disengaged (It's an e-brake on the Z4)
Engine adaptions: All reset with MHD, no change
Engine tune: flashed back to stock with a full WinKFP write and no change.
Parts: Car has relatively new injectors (index 12), HPFP, LPFP and coils.
Log here: https://datazap.me/u/rich/dct-cold-first-gear-engagement?log=0&data=3-14-22&mark=276
Some things I'm suspicious of:
Spark plugs: It's hard to pinpoint exactly when this started but last summer I changed the plugs to NGK 5992 , gapped them to 0.022". I've rechecked the gaps on all of them since and everything is spot on, no fouling on the plugs or anything suspicious.
Downpipes: I also swapped to some VRSF catless pipes at the same time as the plug swap. Could this possibly make a difference? I'm certain I've got no leaks and surely during cold start the car runs in open loop so O2 senors can't be blamed?
Any suggestions are welcome. It's not causing any serious problems for me, but I want to figure it out in case it gets worse.
I'd also really appreciate if anyone else could just grab a log of their DCT pulling away on the first start of the day. Would give me something to compare.
When I first let off the brake and let the car creep forwards the revs will dip a lot and the car labours for a second before pulling away normally, it feels close to stalling sometimes. I've linked to a log of the behaviour with a marker placed where the drive-off occurs. It will keep doing this to a lesser degree for the first couple of minutes of driving then after that it's absolutely fine.
It only happens when the engine is cold on the first start of the day. Outside temps here are about 5-10C so not anything crazy cold.
Some things I've already considered and ruled out:
DCT software: Does it with the latest Z4 35i software and also the 35is software.
DCT Adaptions: I ran through all the adaption routines in ISTA following all instructions and there's no change
Fluid leak: Transmission has no leaks, the sump and gasket were replaced by BMW 1 year ago with fresh fluid.
Parking brake sticking: Does it even when car is left without parking brake disengaged (It's an e-brake on the Z4)
Engine adaptions: All reset with MHD, no change
Engine tune: flashed back to stock with a full WinKFP write and no change.
Parts: Car has relatively new injectors (index 12), HPFP, LPFP and coils.
Log here: https://datazap.me/u/rich/dct-cold-first-gear-engagement?log=0&data=3-14-22&mark=276
Some things I'm suspicious of:
Spark plugs: It's hard to pinpoint exactly when this started but last summer I changed the plugs to NGK 5992 , gapped them to 0.022". I've rechecked the gaps on all of them since and everything is spot on, no fouling on the plugs or anything suspicious.
Downpipes: I also swapped to some VRSF catless pipes at the same time as the plug swap. Could this possibly make a difference? I'm certain I've got no leaks and surely during cold start the car runs in open loop so O2 senors can't be blamed?
Any suggestions are welcome. It's not causing any serious problems for me, but I want to figure it out in case it gets worse.
I'd also really appreciate if anyone else could just grab a log of their DCT pulling away on the first start of the day. Would give me something to compare.
