Hey guys - got a dip in the AFR on E85 that i can't seem to dial out. It goes way rich toward the end of spool right at peak boost, then drops back to 11.9 - 12.1. How do I dial it out?
(See Evoscan chart attached)

 

I have this same problem. Been looking for the answer as well. Hope someone can chime in for the answer.

 

Same problem here, only I have a dip and a spike!!! 4 back to back runs, wtf???

 

No rocket science here...just simple fuel map adjustments. The usual problem is that people try adjusting just the cells that they log the load and RPM at, but during spool, everything is changing very quickly. You have to adjust the cells well before the area you are seeing the issue as well.

 

Thanks for your simple explanation. I will try leaning it out much earlier in the spool to see if I can get it under control sooner. I have tried this approach but only been able to lean the transitional AFRs so far, not those seen at peak boost.

Originally I thought that there might be too much acceleration enrichment going on because it settles immediately after peak boost into the AFRs I want. I also see a similar over rich peak on part throttle acceleration across a wide range of RPMs.

I'll give it a try and report back what I find.

 

Bear in mind in addition to what was posted above, the logged figures from your wideband are usually ~3-7 logging columns behind, so you just anticipate what is going to happen to a degree and then you'll have a feel for what the fuel map needs to be.

 

In for results as well. I am at a loss. My issue is just at the OP described, acts like a 'power enrichment' issue. If i start a pull at 2500rpm, I typically get a dip in AFR at 3200-3500rpm. Fuel map is leaned out significantly in this region to combat this issue. By 4000-4500rpm, AFR is back in line (11.9-12.0 on gas calibrated wideband). Started a pull at 4000rpm with the same tune, got a dip down to 9.9 at 4500rpm. 2 full points rich at the same rpm, same load.

 

fyi - all accel enrichment adders shut off above either 160 load or 180 load (i forget).

 

Thanks for chipping in Mr. Fred. I've tried leaning the transition to max boost but the AFR still goes crazy rich (1 full point) on WOT pulls. Now my part throttle acceleration is lean in transtion to partial boost, so there still appears to be a lot of enrichment going on during positive delta TPS. (No I turned lean spool off a long time ago!)

I'm going to try reducing the Sync Load Accel Comp vs. RPM enrichment values (see atachment) to correct. I've not changed this table (Tephra V7 96530706)since putting my bigger (FIC1050s vs. stock 680s) injectors in, or converting to E85, and the % values may simply be to high for my setup.

I will report back once I have gathered more data. (Determined to get to the bottom of this )

 

This is exactly the effect that I'm seeing, nearly a full 2 points rich at peak boost. This causes a brief, staccato, rich misfire and I'm loggin AFRs at 25 psi of 10.8 - 11.0. Just a thought - I'm running the IX BOV - could it be opening briefly at peak boost?

 

Yep, change that stock BOV mate, they pop open, I had the same issue when I just started so I whacked in a MR metal BOV and she is all good!

 

I think you'll find that adjusting that table will not make any difference. It has no effect above 180 load.

I think this guy is onto something.

 

I'm running a stock 9 BOV as well. I see exactly how the valve leaking could cause our issue. I've read threads where switching valves has cleared up an issue like this, and also seen a few where switching to a different BOV had no effect. I guess if you switch to a different valve that leaks also, you would see no improvement... a tial qr may be in my near future.

 

I'm already running the metal MR IX BOV. I guess the next step is a boost leak test to find out at exactly what pressure it cracks. Looking through my logs I don't see any evidence of the MAP dropping suddenly at peak boost (~25-26 psi)....to be continued.

 

Yep - it made no difference on the drive in this morning. Boost leak test is next up.