Dealer replaced injectors and water pump and now power delivery and shifts are awful.

Aug 17, 2018
26
0
Best answers
0
#1
So late 2017 my car developed a cold start misfire. I booked the car into the local dealership.

On the way to the dealership the car overheated (amber warning) and as I rolled into the dealer car park I got a red warning to stop the car, which I did.

They diagnosed water pump failure and the misfire as faulty injectors.

Both were replaced and the car returned to me.

The following day under cold start I noticed the car felt lazy and I put it down to perhaps a reset of some adaptations by the dealer.

Several weeks later it got no better and then followed several months of back and forth to the dealer for them to ultimately give up as they could find no fault codes nor detect or understand what I was telling them.

Essentially the cars power could feel sloppy and lazy one day then fairly normal the next.

However DCT shifts were snatchy (used to be smooth) and power drops away after shifts before recovering seconds later. It’s unpredictable and unnerving to drive.

I took the plunge to apply MHD stage 1 and this allowed me to play with wastgate settings etc and putting the setting into low lag improved this snatchy and power drop off but it didn’t make the car as it used to be.

A number of forums are telling me different things about the MHD logs I’m pulling but no one has any idea of the cause.

I took a plunge to replace turbo solenoids but that made no difference.

Vac pipes seem to hold vacuum.

I’ve tested diverter valves and they seem ok.

A bit lost now...
 
Aug 17, 2018
26
0
Best answers
0
#3
I’d be very grateful for anyone to review the logs and give me some pointers.

As context, I didn’t see how injectors or water pump could have bearing on this so I looked to the induction side, perhaps something was damaged by the overheat or by the dealership and given almost everything is fragile plastic I thought it a good place to start.
Most seem to agree that some form of boost mean over target is the cause but I’ve no idea how that could be...
 
Last edited:

NoQuarter

Lieutenant
Nov 24, 2017
817
246
Indiana
Best answers
0
#4
I took the plunge to apply MHD stage 1 and this allowed me to play with wastgate settings etc and putting the setting into low lag improved this snatchy and power drop off but it didn’t make the car as it used to be.
Are you talking about the wastegate rattle settings?
 
Aug 17, 2018
26
0
Best answers
0
#5
Are you talking about the wastegate rattle settings?
I bought MHD for the logging but eventually put stage 1 on to remove any idea that the OEM map may be faulty. The fault remained but yes the rattle setting set to more rattle and less lag seems to improve the upshift snatching a little, not a lot tho. Could be placebo.

This isn’t map related. The issue was present at OEM map and a result of something around the dealer visit.
 

NoQuarter

Lieutenant
Nov 24, 2017
817
246
Indiana
Best answers
0
#6
I think if you flash back to stock you will get a clean stock map (not your original).

That will get you back to stock and removing anything that may have happened at the dealer.

Stay on stock map for the duration of the troubleshooting
 
Aug 17, 2018
26
0
Best answers
0
#8
Yes pls move if needed. Just thought DCT section given dct car.

Stock map or mhd, the issue remains the same, snatchy upshifts like the car lifts off the throttle before the shift. Then a drop off of power when the upshift completes then seconds later a little power returns.

On a cold start this means the car feels like it’s going to stall after the shift when in fact it’s just on very little throttle.
 

NoQuarter

Lieutenant
Nov 24, 2017
817
246
Indiana
Best answers
0
#9
Understood. But an OTS map is not designed to properly run the DCT and will makes things more difficult to understand/troubleshoot.
 
May 4, 2017
1,749
758
Plano TX
Best answers
0
#10
@NoQuarter look at his boost target. At wot through the entire range his target never goes above 5psi...that's odd. And then there's the timing drops. He is going crazy negative on timing during a shift, then timing is immediately restored to the previous values, then it goes negative again, then it ramps back in.

Appears to be tune related to me.
 
Nov 18, 2017
753
129
Best answers
0
#12
My best advice is to contact a tuner to diagnose this. BQ is the DCT man.
He’s a decent guy reach out to him.
 
Nov 18, 2017
753
129
Best answers
0
#14
Could it be that his new injectors haven’t been coded correctly and this is the result?
 
Aug 17, 2018
26
0
Best answers
0
#15
This is 100% a tune issue. Please read through this thread. Your tune that you applied (MHD Stage 1) is not designed for a DCT and is very close to the "problem" tune in this thread:

https://bmw.spoolstreet.com/threads/dme-tune-affects-dct-performance.3831/#post-53712
But the issues I have are the same on the stock INA0S map (OEM)? Hence my first post. The issue is after dealer replaced injectors and water pump on stock car. I used MHD to test out a theory much later.
 
Last edited:
Aug 17, 2018
26
0
Best answers
0
#17
The issue isn’t traction control. Thanks for the suggestion though. The drop in power before upshift and the drop in power after exists all the time no matter the driving style or speed. Something is causing this but I’ve absolutely no idea what. The heat of the engine makes a huge difference with cold starts being its worst and once run, left for a while and then run again it’s almost faultless.
 
Nov 18, 2017
753
129
Best answers
0
#18
The problem started when you went to the dealer ?
What could have changed at that point? Injector coding and they may have updated your DME if it wasn’t already.
Strongly suggest check your injector coding.
 

RSL

Sergeant
Aug 11, 2017
258
62
Best answers
0
#19
Torque limiters can occur on shifts with traction control off, but they can be tuned out.
 
Nov 18, 2017
753
129
Best answers
0
#20
Torque limiters can occur on shifts with traction control off, but they can be tuned out.
Why would they be happening on an otherwise stock car though?

For those that don’t know, the DSC runs the e diff and still remains effective with TC set to dynamic. I think it’s still engaged when it’s totally off as well.
 

Create an account or login to comment

You must be a member in order to leave a comment

Create account

Create an account on our community. It's easy!

Log in

Already have an account? Log in here.

Similar threads

Top