Breakup freakout under load after driving for 20 min

ajskalsk

New Member
Nov 5, 2023
7
2
0
Hey guys, I am having an issue where after driving the car for about 20 min, the car will break up nasty under moderate load as if it is bouncing off an invisible limiter. I bought the car with a list of small issues including blown turbos. I have overhauled everything and have this persistent issue. When the car isn't fully warmed up, it will boost through completely fine (I don't beat on it cold don't flame me).

Car specs is 135i w/ 117k miles
Just installed the turbos & Bolt ons, currently being tuned by CD919

Pure600 Turbos, VRSF outlets & CP, ARM Relocated inlets, Catless DPs, AMS 5" Intercooler, NGK 97506 Gapped to .017” per CD919 w/ new Eldor Coils,
xHP stage 3, injectors rebuilt by Vader Solutions, "New HPFP and vanos solenoids" from previous owner, recently walnut blasted intakes,

The best part is the car throws 0 codes, zero. I reset high pressure fuel trims after the injector rebuild but I have no insight from the car itself.

Logs attached, I am at somewhat of a loss on this one and would appreciate any feedback, thanks.

https://datazap.me/u/ajskalsk/street-pull-breakup-log?log=0&data=3-5-20-21-22-23
 

carabuser

Lieutenant
Oct 2, 2019
881
1
778
0
UK
Ride
Z4 35i & 335i
Something doesn't add up with the boost reading, it just seems to freeze at exactly 17.7psi like it's hit the maximum scaling and doesn't seem to follow the WGDC at all. Check the positioning and wiring of that sensor. Maybe even just go back to the stock one for diagnostic purposes.

Usually issues like you describe are caused by people hiding error codes in the tune. When you set an error code to "00" it doesn't actually stop it happening, it just prevents the code reader from seeing it. So in future when that code triggers you just get limp mode internally in the DME but no notification for a code reader to see.

Try running an MHD OTS map and running some logs.
 

ajskalsk

New Member
Nov 5, 2023
7
2
0
Why isn’t the throttle at max on the pull?
I’m not going 100% throttle on these pulls because the power cut issue is much more violent at 100% throttle and until I get it somewhat sorted I want to avoid excessive stress on the motor if there happens to be a hardware issue.
 

ajskalsk

New Member
Nov 5, 2023
7
2
0
Something doesn't add up with the boost reading, it just seems to freeze at exactly 17.7psi like it's hit the maximum scaling and doesn't seem to follow the WGDC at all. Check the positioning and wiring of that sensor. Maybe even just go back to the stock one for diagnostic purposes.

Usually issues like you describe are caused by people hiding error codes in the tune. When you set an error code to "00" it doesn't actually stop it happening, it just prevents the code reader from seeing it. So in future when that code triggers you just get limp mode internally in the DME but no notification for a code reader to see.

Try running an MHD OTS map and running some logs.
CD919 got back to me and said it is an overboost issue and sent me a new revision, looking back at previous logs the boost reading doesn’t flatline like the most recent logs. I’ll double check the wiring and pin out on the map sensor, I’ll also see if the tuner is hiding any codes because that would check out if it is overboosting but he hid the code. I’ll get some new logs on the revised map and keep you posted, thanks for the feedback
 

ajskalsk

New Member
Nov 5, 2023
7
2
0
.017 is a very tight gap. I tried .018 just the other day for the first time and car backfired on decel when revved in neutral 😂
Yeah I thought so too but that’s what the tuner recommended. New log seemed to fix the overboost issue but it has been raining so I haven’t been able to get any good pulls to know for sure but it hasn’t really felt like a misfire, more of a traction control pulling power type feeling
 

ajskalsk

New Member
Nov 5, 2023
7
2
0
Checked the wiring on the map sensor and it seemed to be good. When doing a pull tonight I caught on the log that the rpm drops to 0 then bounces right back. I suspect a crankshaft position sensor issue. Has anyone experienced something similar before?

I have noticed there is an occasional slightly rough idle and crank times can vary by about 1 second from usual. I have one on order and will report back with results.

 

ShocknAwe

Captain
Jan 24, 2018
1,491
1
737
0
Charleston, SC
Ride
N54/3 1er ///Mutt
I just repinned the factory harness but it’s 16 year old bmw plastic so good chance a pin could not be making sufficient contact
I was having a ton of issues mid 2023, thorough cleaning of DME and other connections helped to resolve, not likely your issue based on your evidence but molehills stacked high enough can make mountains.