Weird cold starts - just an m3 characteristic ?

[SilverSlug]

@dpaul Thank you for that clarification.

So, if I upgraded to 241E (erased Dinan), and then re-uploaded my Dinan tune… Is there a benefit to doing that?

[Lozza47]

Originally Posted by SilverSlug

Why Shell?

I use only Chevron gas. It has an additive called Techron, which is a great fuel injector/system cleaner.

I have to use Shell for company tax purposes. That being said, I will fill up with another brand and run it to quarter tank and see what happens.

[spammysammich]

Originally Posted by SilverSlug

@dpaul Thank you for that clarification.

So, if I upgraded to 241E (erased Dinan), and then re-uploaded my Dinan tune… Is there a benefit to doing that?

Check with your Dinan retailer to see what the tune is based on. If you want to retain 241E features, you want the Dinan tune to use it as a base. But I'm not sure how often Dinan updates a tune for a car this old.

[SilverSlug]

I just spoke to Dinan. They said that the Dinan software works with whatever version of the BCU (hardware) and PCU (software) is on the car.

And the last time they updated their tune was in 2015, which was when 241E was released, so sounds like it would be compatible.

[spammysammich]

I just had the Dinan ECU and DCT tunes on the car in 2020 but I haven't checked to see what base was already on my car. I suspect it wasn't bumped up to 241E as I do not have the full service/mod history of the car.

Also, it wasn't me that had the tunes done, previous owner decatted the car and had a shop in Portland add the Dinan tunes.

[SilverSlug]

Originally Posted by spammysammich

I just had the Dinan ECU and DCT tunes on the car in 2020 but I haven't checked to see what base was already on my car. I suspect it wasn't bumped up to 241E as I do not have the full service/mod history of the car.

Also, it wasn't me that had the tunes done, previous owner decatted the car and had a shop in Portland add the Dinan tunes.

I have the Dinan OBD tuner cable if you want to borrow it to reinstall the Dinan tune after you upgrade to 241E (I'm not sure if any regular DCAN cable will work with Dinan, but it may).

Otherwise you'd just need to call Dinan to give them your VIN, and have them email the tune file to you.

Upload takes like 20 mins total.

[Lozza47]

Just an update on this - seems like changing fuel from Shell V-Power 98 to BP Ultimate 98 has smoothened out my cold starts. Will run a few tanks through and confirm but looking good so far.

EDIT: Forgot to mention I tried the ecu update a while back and it didn't fix the cold start issue. I was still running V-Power during that time.

[Signature Wheel BMW]

Try replacing the the fuel breather valve. Very common for these to get clogged up or the actuator mechanism to stop working. Cheap part, just remove the plenum and it's right there. Mine wanted to stall after full tank.

[Tommysalami]

Replacing my low pressure fuel sensor seems to have fixed this for me. Not too expensive and easy to replace. Need to get the new version part # with the adapter.

Took a couple days of driving for the car to adapt to the sensor but it seems to be gone now.

https://www.fcpeuro.com/products/bmw...xoCq40QAvD_BwE

[BayAreaE93]

To reiterate what some others have mentioned and also add a few points from my experience:

I experienced the exact same issue when I first bought my car. Rough, long cold starts, and once started, sometime a bouncing idle. What fixed this for me:

New pre-cat O2 sensors
New low pressure fuel sensor (Bosch updated sensor)
Adaptations reset
Priming the fuel pump (pressing start button twice)

Having a bad breather valve, ground cable, spark plugs, injectors, fuel pump, coils, etc. can also cause this.

[Lozza47]

Originally Posted by Lozza47

Just an update on this - seems like changing fuel from Shell V-Power 98 to BP Ultimate 98 has smoothened out my cold starts. Will run a few tanks through and confirm but looking good so far.

EDIT: Forgot to mention I tried the ecu update a while back and it didn't fix the cold start issue. I was still running V-Power during that time.

So I changed back to Shell V-Power 98 and after the 2nd straight fill up, the jumpy cold start has returned.
After all this, I'd say my issue was definitely fuel brand and/or quality. BP seems to be a better fuel for the m3. Sounds silly but ah well