I am having an issue with my AFR dipping by about a half and sometimes even a full point when I hit peak boost. At first I tried to tune it out but It moves around depending on when I spool.

I have boost leak tested twice this week but they weren't the greatest tests as I wasn't able to get the pressure up past 20psi with the compressor setup I was borrowing.

Is this a spark problem, boost leak, am I missing something obvious or should I continue to try and find a high pressure leak? I have a COP setup, new spark plugs, boost leak held at ~15 psi for a while. I'm also seeing super high WGDC values in order to hold boost up top but that might just be my WG preload.

 

By dipping, do you mean going rich or lean? Have you datalogged it?

 

lean spool on ????

 

are you using High-Z injectors?

 

Thanks for the replies. By dipping I mean going rich 0.5-1.0 Gasoline calibrated AFR points. I am seeing this in my fatal of only as it is too quick to see it on my gauge and trying to keep the car straight when it hits 25psi is my main priority.

Lean spool is off and I am using Precision low z 1200's on e70

 

Huh? Is the boost spiking you into a load range that's rich by any chance?

 

Please post a data log.

 

Haha god damn autocorrect. "Logs only" I meant to say. I wish it was that I'm going into an untuned portion of my map but it happens at all different rpm depending on when I start my pull. It's very weird

 

I'll get a log up tomorrow or later tonight

 

When you post it also put up a screen shot of your fuel map.

 

I have this same issue running e85 and pte 1200's. I tried to tune it out with fuel maps, lean spool, etc.

I've found several threads saying the same thing and I've learned to just live with it. It seems like a throttle tip in enrichment setting that cannot be adjusted and the bigger injectors and e85 make it obvious.

If you find a reason, please share. Good luck.

 

I'd bet it's a boost fluctuation leading to AFR fluctuation

or
it's the accel enrichment (that adds fuel when load is rising) that stops adding fuel when you hit peak load. Maybe trying to be less agressive with accel enrichment and add more fuel directly in the fuel map. I have this occuring in my car as we speak. Not major though

 

I don't really mind it since it's going in a "safe" direction instead of going lean at peak boost. It usually shows up as a super quick transition from ~12.1 to 11.5 or so and then back up to 12 ish after peak

 

Could also be your BOV leaking slightly at full boost. I figured this out about 7yrs ago by testing flipping around the bov backwards and the rich dip went away. Of course, don't run your BOV backwards as a solution.

 

Nice advice, but this is unlikely for me, because i'm SD + the boost isn't fluctuating even a little bit.
But yeah definitely something to check