STFT During WOT pulls

[LaBrat]

Hey everyone, first post!

I have been battling an issue with my Jeep for a long time now, where during a WOT pull i 90% of the time get a STFT between 0-4.7% on bank 1 and bank 2. when at 0% STFT i hit 12.7AFR, right where I want it.

Every time this happens it goes to the rich side, sometimes to around 11.6-11.8 AFR.

here is the build -

2010 Jeep Commander 2wd
SBE 5.7
Custom grind texas speed cam - 224/234 0.602/0.597 113 LSA
6.4 car intake
long tube headers
3 inch catless mids
3 inch dual catback, x pipe
8hp70 swap
Edge racing 3400 stall
custom CAI
93 octane

Things i have done to try correcting this -

- perfecting my VE with multiple long drives. I believe it is in great condition.
- making ECT rear for o2 sensors to 370 degrees
- changing enable delay for rear o2 to max value
- changing power enrich WOT threshold a few times between 2.19v to 3.19v (same with pedal WOT request in torque management)
- changing VE limits to be higher (165% or so)
- changed catalyst protection temps up and down without any success


I am sure there are other things i have tried, but nothing has effected this at ALL. from all i know, B1S1 and B2S1 control air.fuel at part throttle until the cutoff point driven by power enrich WOT threshold, so i should have ZERO fuel trims effecting WOT.

asking some better tuning friends indicated that the only driver here can be the rear o2's controlling fuel trim for component protection.


what am I missing?

Log and current tune attached.

st fuel trim on wot.hplAJL Tuning PLS STOP ADDING FUEL 4.10.hpt

[LilSick]

what wide band are you running?

why are you reading f/a?

why arent you logging it?



that thing is pissed when you stab it at 1500 and there is 17 degrees of timing in it lol

weird timing curve you have constructed... why are you pulling timing up top?

why are you giving it 23 degree at 4800???

that is a lot for pump gas

17 is a lot at 1500 too

what state are you in?

[LilSick]

your start up injector pw base looks whacked

table 34000

can you post or email the stock file?

[LaBrat]

wideband is an AEM X series 30-0300.

i was taught to read FA first and i havent had much reason to read it inversely yet, what would it help knowing the inverse AF?

ive never taken the time to hook up the wideband to HP. i have the pro feature set but havent hooked it up.

for the timing, a previous tuner set me up and I modified from there. (guy quit on me, so i began tuning after that). I haven't noticed all that knock voltage until now surprisingly, i always pay attention to the higher RPM bands. Ill work on that.

honestly the timing used to be more up top, 25.5 degrees. I was also told that was a lot, and i backed it off 2 degrees just to be safer. I do understand 23.5 is still a good bit of timing.

I am in Michigan.


I checked the 34000 table, its pretty close to stock and my startups are mint from -10 degrees to 100 degrees. I do see the spike at really low temps and high counts, unsure if that needs to be in there or not.

First Read Jeep Commander After bench flash and beta.hpt

[HaasExp]

I am sure there are other things i have tried, but nothing has effected this at ALL. from all i know, B1S1 and B2S1 control air.fuel at part throttle until the cutoff point driven by power enrich WOT threshold, so i should have ZERO fuel trims effecting WOT.

Positive fuel trims can and will transfer over into open loop by default in many OEM PCMs.
What I noticed in your log was that the average STFTs + LTFTs immediately before your WOT pull at the end of your log were overall positive. Hence it held +4.7% trim on bank 1 and +3.9% trim on bank 2 into OL.

To try and avoid this I like to target around -5% STFTs + LTFTs across the board. This gives you leeway for atmospheric changes that can push the trims positive.
On these FCA PCM's I've noticed that negative fuel trims will not be maintained into OL. Only positive ones.

[LilSick]

i was suggesting you read lambda

unless you know the stoich of what is at yer pump?


i have heard others talking about positive trims carrying over

that is something if it is really happening

gonna do my best to test that theory with wide band and lambda

[LaBrat]

So after some trials, I found that my previous change to driver demand pedal tables made my throttle more aggressive, so I believe the knock down low is burst knock. I like the more aggressive pedal feel, so I pulled some timing like suggested and the knock went away. Thanks for pointing that out!


I added 5% VE in a few key areas and I believe it is going to help, but the issue is still present.

I will continue to increase fueling and see if the issue goes away.

Any other suggestions on this? The issue seems like a bandaid more than a real fix.

I?ll post another log after I get some time and more time attempts in.


@lilsick, I run pump 93 and normally I aim for 12.4-12.7. I know I can switch it over to lambda on the gauge, what would be a good number to shoot for with this setup?

Is the E content of 93 inconsistent similar to pump e85?

[LilSick]

.85

maybe .875

depends on your fuel... that is why AFR is not as accurate



Not with Pearson Fuels : )

we are blessed. our e85 is 90%. always

you gotta test yers. YRMV

[LaBrat]

So,

Been playing around a bit. I got VE to sit "roughly" -5 percent, sometimes more.

That did NOT seem to solve the issue.

in the log provided, you can see at 9m52s that the STFT is around -2%, and once going WOT it still goes positive.

current tune provided as well. I changed a few other small things that are unrelated, but also changed my rear o2 sensor ECT to 350 again just to rule it out..

Any other advice?

went positive fuel trim even with increase VE.hpl AJL Tuning ve fueling stuff 4.13.hpt

[LaBrat]

anyone else have any insight on this?

[John_Carter_2]

anyone else have any insight on this?

I will take a look at it to you shortly

Not a specialist, but experience on my own cars

[LaBrat]

Some more questions on this -

One set of tables ive not had in my OS is transport delay.

I help my buddies out sometimes with their tunes and logs, and I've noticed that my o2 oscillation is much slower than theirs. at idle my AFR's will swing a good bit centering on 14.7, which confirms what the B1S1 and B2S1 are showing in the log.

I am going to look into getting HP tuners support to add these tables for me, as I looked at some tunes that include long tube headers and normally transport delay is indeed modified.

Are there any other tables I should look into adding that can assist my problems?

[LaBrat]

Update on this, I did end up getting the transport delay tables added in. After modifying them (multiply 1.5x on most cells) I fixed my problem with the o2 oscillation being slower, much more reactive.

But, it did not fix my issue. My AFR's still go rich sometimes, but other times its perfectly on the mark at 12.6/12.7. Every time it happens, the log shows a STFT of anywhere between 0.1% to 4.7% on either bank, sometimes both but equaling 4.7%. Normally brings the AFR's down to 12.0, nothing to be scared of but it would be nice to see consistency.

BUMP, anyone else see this issue before?

[LilSick]

yep

its in open loop and it is not fuel tech

the hellcats operating system does a better job here

[MoBoost]

Just to confirm, I have 2010 srt8 dodge Challenger Auto, that randomly turns on STFT during WOT on just ONE bank. It's a sh!t show. Going open loop is the only solution so far.

[fumanchu182]

If you do not have a wideband hooked into the prolink you are doing yourself a disservice. Spend 20 hours debugging this fuel trim issue or spend two hours getting the prolink configured and one more hour dialing in fuel trims at WOT. That's the path of least resistance. Attempting to use the narrow bands for fueling is not going to happen for WOT on any MOPAR.

Here is an example. You have made a rip here... but guess what, you have no data because the narrow bands aren't active. The system went into Open Loop, which means it will use a TABLE and not any sensors.

Screenshot (2).png

also add pratio and throttle torque source to your channels list

[LaBrat]

the funny thing is I have a Prolink, never hooked it up.

What i normally do is i'll have my laptop open and logging, and I will watch AFR on the wideband during a pull to see if it is going low (12.0ish). When i notice AFR go low Ill check the laptop as wel, giving me the correlation. Although the AFR number isnt on the log, its more than enough to tell me what the issue is. to be clear I am not relying on narrow band for tuning WOT.


Next time I log Ill add Pratio and i have been meaning to. I also have tried adding throttle torque source previously and it was not an available PID. Ill download a fresh beta and see if its there now.