HappyLegs

Hello, I brought my finished project out for a shakedown at Whiskey Hill (Palmer, MA) a couple weeks ago. All things considered it was very successful. During the last session however I experienced some breakup and the reason is not jumping out at me. It first started while in 3rd gear, higher rpm's, upshifted to 4th and continued on. Then it happened in 4th. Feels like car just cuts power for a second, I lift, and then when I press the gas again it feels normal. Everything looked normal on my gauges, it doesn't appear to be water or manifold temp related. Would anyone mind taking a look? Attached is my build sheet for reference, current tune, and two 10 minutes logs from that track session. I can say for sure that it happened during the log labeled 12.44.20 as that is when I decided to call it quits, something is wrong, and went back into the paddock.

Thank you for any help!

-Jonathan

engineered2win

There's not a ton of channels being recorded, so that makes it a bit more difficult. Also is there a particular speed / load /tps this is occurring?

First off I think you need to fix your VE table. Your fueling is off compared with your AFR target table. You don't have fuel correction or target AFR recorded, so I'm just going off theoretical.
For example:

Your AFR before the shift is ~10.8 and your target at ~6000rpm/180kPa is 11.6. Then there is a massive lean spike right as you return to WOT where your AFR hits 17 and 5500rpm/114kPa. So I would expect to drop a few cylinders during that tip-in due to the lean condition + boost. There's also a knock concern too.
And looking at the rest of the log there are also conditions where your AFR is <10, which is rich misfire territory. A lot of them are during overrun, but some are during tip-in and low throttle positions.


I think this is at least partially caused by your VE table being off and your EGO authority table is basically 0 here, so you're essentially open loop. At the tip in condition you're at about 115kPa, so a bit less than 5% allowable correction.

I would suggest increasing the allowable control to more like 15-20%. Once you have the toon dialed in you can consider reducing this. I would also suggest using the separate positive and negative authority tables if you're concerned about something happening causing a lean condition.
The lean condition during shift could also be caused by Accel Enrichment. I'm not so familiar with MS implementation of transient throttle enrichment, but keep in mind that these transient conditions are essentially open loop. You're not going to have any significant amount of fuel correction here due to the o2 sensor delay, so your main sources of error are VE and AE calibrations until you're in a condition long enough that the o2 sensor can catch up.

Also you can probably dial the coil dwell back a bit. This isn't going to cause a misfire, but you're driving the coils pretty hard. 2.5ms @ 14v = 16 amps
Here's a discussion on R8 coil dwell settings: https://www.hpacademy.com/forum/gene...dwell-settings

HappyLegs

Engineered2win, thank you for taking the time to look at my post and to offer your insight. Appreciate it!

While looking into the things you mentioned I noticed my dead time settings differ from manufacturer spec. I setup all the basics on sensors/injectors/coils before the car was put on the dyno and I remember the tuner changed those dead time #'s in response to a low voltage issue (alternator bolt vibrated out) that popped up; so he never changed them back after the voltage issue was sorted. If not one evening this week then over the weekend I should be able to start making some changes to the VE table, give the EGO Authority table a little more freedom, and run some logs. I'll report back.

I'm thinking I may add some more delay to the overrun (currently at 0.7) kicking in. Maybe change to 2 seconds.

StaceyRapp

Nice one, I love it.

natewin

A friend's 3" downpipe cracked right at the v-band first session of a track day last weekend @NHMS. Breaking up, wouldn't idle well after. Was also wrapped. I noticed puffs of smoke from that area when he was trying to start it.