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-   -   Quick highway pull shows suspicious MAP readings in log. (https://www.miataturbo.net/engine-performance-56/quick-highway-pull-shows-suspicious-map-readings-log-98022/)

Keuzy Sep 10, 2018 11:16 PM

Quick highway pull shows suspicious MAP readings in log.
 
1 Attachment(s)
Did a quick 4th gear pull on the highway to check AFRs at boost, but when i checked the log, it shows erratic MAP readings. Im worried this could be a sign of preignition. anyone have experience with this anomaly? fluctuates between 160-170 kpa, as the attached photo suggests.

sixshooter Sep 11, 2018 01:50 PM

The difference between 160 and 170kpa is 1.45 psi. It's probably your wastegate door not holding steady and oscillating as a result of your timing fluctuating so much. Reduce the difference between rows in that area and see if it doesn't settle down.

Erat Sep 11, 2018 05:44 PM

It basically mirrors your timing.

Impressive.

ridethecliche Sep 11, 2018 06:42 PM


Originally Posted by Erat (Post 1501242)
It basically mirrors your timing.

Impressive.

First thing I noticed as well.
OP, post log and tune...

sixshooter Sep 11, 2018 10:31 PM

My point was if your tune is such that 1.45 PSI will make a significant swing in your spark timing then that is likely the source of your oscillation.

Keuzy Sep 12, 2018 07:59 PM

2 Attachment(s)
Tune and log attached. I tried to make a smooth slope in the timing as boost is increased. If your responses are anything to note, it looks like the slope could be too steep?


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