New to tuning, chasing a stutter/hesitation

[BrownDog185]

ok so ive managed to log the problem with your preset

on the second pull in this log approaching the 3000rpm mark you can see the hesitation in the RPM line

[Ugnius @ VersaTune]

Convert to .csv before posting the logs on the forum. Those who can help you don't necessarily have the MS6/6MPS specific version of versatuner and will not be able to import these logs.

BTW all editions of VersaTuner (including free) can now open logs from any supported car.

[mituc]

BTW all editions of VersaTuner (including free) can now open logs from any supported car.

Awesome news! I did not try this lately and I probably missed this info in the release notes!

[mituc]

ok so ive managed to log the problem with your preset

on the second pull in this log approaching the 3000rpm mark you can see the hesitation in the RPM line

Yeah. So this happens because you are reaching the throttle reduction boost limit (31PSI MAP). Common causes for this:
- disconnected or cracked EBCS-to-wastegate actuator hose;
- disconnected or cracked EBCS-to-turbo inlet pipe hose;
- corroded or blocked wastegate actuator arm;
- cracked wastegate actuator membrane.

If it's not one of the most common causes which are the first two, the last two can be diagnosed by hooking up an air compressor to the wastegate nipple, pressurize to 0.8-1BAR and see if the arm moves. At about 0.8BAR/12PSI the wastegate should be fully open which from outside can be seen as full travel of the wastegate actuator arm.

[BrownDog185]

ok awesome, this would make sense as why the high load maps are worse and why my previous flash tune works without issue

the tuner that did the flash said he had to reduce boost to 15psi to keep it happy, he assumed it was due to the owner using 91 fuel

ill sus out the lines tomorrow and post an update, cheers

[BrownDog185]

any ideas as to why there is a miss as the throttle is opened after coasting

[mituc]

Throttle body may need cleaning. Also it may be related to sparkplugs wear or fueling. Log it!

[BrownDog185]

i actually managed to log it in the posted log
its not an instant miss but is shortly after the throttle is opened

log shows the desired AFR dips where the miss happens

[BrownDog185]

1

[mituc]

I would rather look at some values than a picture. If you have the actual log please post that.