E85 OFT tune Bucking/surging

[Vmax911]

Hey all,

Wondering if you can help me out. I'm experiencing bucking/surging at low(ish) RPM and high throttle. I'm running the OFT 2.076 E85 tune. This is my third tank on E85 this season. Last year I didn't notice this at all. I thought I had bad gas at first, but know that I have filled up twice since the switch so I don't think gas is the issue.

I'll try to link to a log that shows what is going on. I have good fuel trims and IAM is always at 1.0. Any thoughts or suggestions (or what parameters I should log)?

http://www.datazap.me/u/vmax911/buck...zoom=1661-1797

[steve99]

Originally Posted by Vmax911

Hey all,

Wondering if you can help me out. I'm experiencing bucking/surging at low(ish) RPM and high throttle. I'm running the OFT 2.076 E85 tune. This is my third tank on E85 this season. Last year I didn't notice this at all. I thought I had bad gas at first, but know that I have filled up twice since the switch so I don't think gas is the issue.

I'll try to link to a log that shows what is going on. I have good fuel trims and IAM is always at 1.0. Any thoughts or suggestions (or what parameters I should log)?

http://www.datazap.me/u/vmax911/buck...zoom=1661-1797

Ill say load limits need fixing
Also maf scaling

It running pig rich when you get on throttle, richer than 11 as that limit of stock o2 sensor scaling

The load limits stop it running super rich and very low or retarded timing at high loads low rpm

You dont have total ignition tiking in log but i suspect it will be very low or retarded when you get on throttle coupled with rich it will bog

[RedFRS4me]

funny thing is I had this a while ago. what I did was clean my K&N drop in filter and that fixed my bogging issues!. It wouldn't hurt to check the filter.

[Vmax911]

Originally Posted by steve99

Ill say load limits need fixing
Also maf scaling

It running pig rich when you get on throttle, richer than 11 as that limit of stock o2 sensor scaling

The load limits stop it running super rich and very low or retarded timing at high loads low rpm

You dont have total ignition tiking in log but i suspect it will be very low or retarded when you get on throttle coupled with rich it will bog

Thank you for the advice. I've spent some time looking into this "load limit" thing you speak of. It looks like the definitions Shiv provides from OFT does not include the load limit tables for his 2.0xx tunes. I looked around on github and didn't find one that seemed to work with my old 700C tune. I am a bit of a noob at this, so maybe I'm missing something.

However, I did find in your OFT tuning thread where Shiv mentioned to slightly lean out the low RPM/High load open loop fueling table. I will give that a shot.

Here is another log showing the same issue, this time with ignition timing. http://www.datazap.me/u/vmax911/e85-...6&zoom=387-439

Originally Posted by RedFRS4me

funny thing is I had this a while ago. what I did was clean my K&N drop in filter and that fixed my bogging issues!. It wouldn't hurt to check the filter.

It's never a bad idea to check the air filter, I should have thought of this! Thanks for the reminder, I'll check it out.

[oldgunfan]

Do yourself a favor. PM Wayno and send him a contribution and he will send you all his newest Tunes. I'm running his V124 E85 tune and my car is running like a Raped Ape.

[Wayno]

Originally Posted by oldgunfan

Do yourself a favor. PM Wayno and send him a contribution and he will send you all his newest Tunes. I'm running his V124 E85 tune and my car is running like a Raped Ape.

Thanks mate. I've uploaded them all here to make the process a bit faster, instead of messaging back and forth for days.