[Ron Jeffries]

Turn on tune, it fails, turn off tune it doesn't fail.

Prosecution rests.

On the other hand, of course, it could be triggering a flaw somewhere else. All we need is reasonable doubt to declare it not guilty ...

[SwallowedABug]

Originally Posted by Clear_Blue22

I’m assuming it’s not a mechanical issue. I have 6,000 miles on the car. I drive near sea level, and I run 93 octane almost always from shell unless I can’t help it. The only thing I have done to the car so far is the tune. The only reason I’m not blaming the tune, is because I appear to be the only one with the problem.

Running an M240i xDrive w/Dinan Stage 1 and experiencing the same phenomenon under virtually the same conditions. The feeling of power loss you describe, as if you can feel the timing pull or fuel cut, is more pronounced/violent when accelerating moderately, but steadily at passing speeds. I'm also experiencing the same problem at WOT: yesterday I dropped from 6th to 5th to pass and just floored it...while the RPMs where climbing, I got that instant and succinct loss-of-power that made us lurch forward for ~2+ seconds...then the car seemed to recover but was not accelerating despite ~2K RPMs of room before redline.

It's been in an out of service every 10 to 14 days for the last 2 months for this problem (which has been accompanied by CELs and chassis/drive train faults). They've replaced boost and charged air sensors to no positive effect. I can't seem to replicate the problem in Bypass, but as long as the Dinan is physically connected to the car, I don't think I can truly eliminate the possibility that the harness or the box is the problem. So, I'm disconnecting it today...we'll see what happens over the next 10 days or so.

[XutvJet]

To those experiencing the issue:

1) What fuel grade and make are you using?

2) Is the delay more apparent as ambient temps are higher (80+ degrees) and when the motor is fully warm and heat soaked from around town driving?

3) Which driving mode are you using? Does it act the same in the modes that allow of some wheelspin? The nannies in these cars are hyperactive and it is quite possible with 60-70% throttle in a lower gear, power can be cut even when the traction light isn't flashing because the DME (ECU) is anticipating spin. I've felt this on numerous occasions when temps are hot and I'm in a mode that doesn't allow for spin. Basically it feels like there's no boost at all. A switch to a more aggressive mode with wheelspin allowed stops the issue. I would imagine with a higher boost setting/tune, this issue feel more abrupt due to the big increase in low rpm torque.

While I haven't experienced this specific power delay issue as noted by the OP, I can certainly feel minor power hiccups when running the higher boost settings with my Dinan Sport when temps are above 80 degrees and motor is heat soaked. This is with running 93 octane too. I would imagine 91 octane would result in more obvious and dramatic hiccups and possibly delays. The DME is very quick to respond and cut power for various reasons, especially when it's hot out and the DME is trying to keep things safe.

[Clear_Blue22]

Very interesting to hear of someone else with the same issue... I can tell you that while my first unit was sent back to DINAN for inspection I was without a tune for about 2 weeks. The car didn’t have any of the issues I experience with it. I got the replacement in about a week ago now and have had the exact issue at the exact same rpms with both units. In bypass mode I don’t have any issues at all either.

I am running 93 Octane from Shell. Amount of fuel in the tank makes no difference. Ambient temps have been between 70-100 with no difference. And I drive it in Eco mode very gently until the engine oil temp gets to around 175 or higher. I had considered that possibly the engine heat could be messing with the sensors by heating up the wires, so this weekend I am going to install some plastic heat shielding similar to what is on the factory wires. The one thing I’ve noticed that makes it occur the worst is being in a higher gear, for example 5th, and coasting off the gas until around 2400rpm and then casually adding power again. Even more evident Is a spot on my way to work is a long somewhat steep hill. I can easily climb it and maintain speed only downshifting to 5th from 6th. When doing so the car will lurch and sputter near the 2800rpm range pretty bad forcing me to either shift back to 6th or down to 4th just to change the Rpms and it drives just fine.

[SwallowedABug]

Originally Posted by XutvJet

To those experiencing the issue:

1) What fuel grade and make are you using?

Running 91; however, have also experienced problem running 100.

Originally Posted by XutvJet

2) Is the delay more apparent as ambient temps are higher (80+ degrees) and when the motor is fully warm and heat soaked from around town driving?

Temps range from 70 to 110--NV is hot this time of year . The M240 heats up pretty quickly. I wait until idle drops, then take it out in Comfort for roughly 2 1/2 miles before I hit the highway, then I hit Sport or +.

Originally Posted by XutvJet

3) Which driving mode are you using? Does it act the same in the modes that allow of some wheelspin? The nannies in these cars are hyperactive and it is quite possible with 60-70% throttle in a lower gear, power can be cut even when the traction light isn't flashing because the DME (ECU) is anticipating spin. I've felt this on numerous occasions when temps are hot and I'm in a mode that doesn't allow for spin. Basically it feels like there's no boost at all. A switch to a more aggressive mode with wheelspin allowed stops the issue. I would imagine with a higher boost setting/tune, this issue feel more abrupt due to the big increase in low rpm torque.

What I'm experiencing occurs at highway speeds--not enough torque to generate wheel spin. But, yes, it has happened when accelerating through in lower gears (3-5) to ~6 to 6.5K RPM.

Admittedly, I'm not paying attention enough to note all the conditions/symptoms each time they present. But, depending on what BMWNA has to say about status of my case, I'm going to need to.

[Ron Jeffries]

I'm surprised BMW is even slightly interested given that it only happens with the Dinan turned on.

[SwallowedABug]

Originally Posted by Ron Jeffries

I'm surprised BMW is even slightly interested given that it only happens with the Dinan turned on.

They are interested (or not) in the blown motor they recently replaced under warranty.
I'm roughly 4k miles into ownership of this CPO I bought this past Winter. The motor
blew w/o warrning, they replaced it, insisted the Dinan could stay connected, and the
car has been in service every 10 to 14 days since for all manner of codes as well as
chassis and drive train faults.

[babaikram]

Originally Posted by Mr Carrots

Yup, either tune it or trade it in for a 235/240 if the lag bothers you.

I never drove a 230/228 as I was intending on buying a cpo m4 before I settled for the 240, but every other turbo 4 I tried felt a bit laggy, even the latest cla 45

It is really bad with CLA 45 AMG