Hesitation and high KR Cold weather issues?

Here are a few logs from runs at the track last year. The first was a chilly night at 50F (Screen shot) the second was a lot warmer chart of HP side of the fuel system VS speed. As you can see it will hold over 2K PSI during the whole run down the quarter. At least it did. I know that it had similar issues last spring, I wish I still had the logs to compare when I had the issue to see if it was doing the exact same thing. 

Hence my thoughts on the fuel being the culprit here. I am running out of ideas. And am getting very frustrated. I guess the only way to rule out the fuel is to get some summer fuel. Any chance one of you boys down in the south can ship me a few gallons of your stuff? ;) I am still waiting on the race gas store to open for the season.   

 
SHOnUup said:
Sorry man...you'll be back there soon I bet.

How's the LOR gauge been reading with the fuel

Rich
Click to expand...

No worries ;) the LOR gauge works perfectly. It's at -1 when I had the 91 no corn it was reading -0.94 with the 91 tune.


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I actually have had to misfire events in last 12 days.

1st one the wife just filled up at same station we've been using for last 8 months. 2 miles down the road the car starts to stutter and she pulls over and pulled a misfire cylinder 5. Yes, she stopped and used torque app to pull the codes prior to calling me...she crawled home and I checked everything. Tuning device only pulled generic misfire code. Cleared it and no sign of it.

I put in just 93(10%/e) and no added corn next fill up...still fine

Next fill up I add 1 gallon corn...down from 1.25 gallons of corn to the 13 gallons of 93. It happens again a few miles down the road when stopped. Clear codes and it's gone...weird

Car feels great, pulling great #'s across the board....actually better #'s than usual?

Rich

 
SHOnUup said:
I actually have had to misfire events in last 12 days.

1st one the wife just filled up at same station we've been using for last 8 months. 2 miles down the road the car starts to stutter and she pulls over and pulled a misfire cylinder 5. Yes, she stopped and used torque app to pull the codes prior to calling me...she crawled home and I checked everything. Tuning device only pulled generic misfire code. Cleared it and no sign of it.

I put in just 93(10%/e) and no added corn next fill up...still fine

Next fill up I add 1 gallon corn...down from 1.25 gallons of corn to the 13 gallons of 93. It happens again a few miles down the road when stopped. Clear codes and it's gone...weird

Car feels great, pulling great #'s across the board....actually better #'s than usual?

Rich
Click to expand...
Weird, mine on the other hand has yet to throw a code at me.


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Alrighty now, beginning to see a trend. I have posted a few interesting logs below. All the screen caps are from 0 and are at WOT. The first is stock tune, second is from a run last year at the track 93 V8 tune and lasty is today with the 91V7 CW. upon further examination the falling high side fuel pressure stands out. However when I compared the throttle plate position across the three I see the ECU modulating the plate in the first 2 but not the third. Even the track run has this modulation. The one from today it sticks wide open during the pull. The same goes for the WOT roll pulls (only after tuning to something other than stock). Same deal. The throttle plate sticks wide open. Is this a learned behaviour? Does the ECU adapt over time? Any thoughts would be great.   

The one you are looking for is TP1 %
 
Shoboat I don't think it's so much of a learned thing as much as actual torque vs commanded torque...this is what I'm focusing on in my tuning at the moment...the car will use the throttle plate to control torque output...it's really difficult to match the commanded torque tables with actual torque...hard for me to explain since I don't fully understand it...the tune maybe commanding more torque than what another system in the car wants so the throttle will close....then open and or fluctuate

There are switches in the tune to shut that off but then if u exceed other limits the throttle can still modulate..it's frustrating...there are torque limits for the axles, trans, inputshaft...and they all need to jive.

I think I get my tune where I want it and the throttle will stay open then later on I log again and my throttle is doing weird stuff. I can't feel anything but it should be open...it's the joys of drive by wire....if I lower boost I can keep the throttle open...when it closes its usually because the ecu doesn't like something or is protecting something.....torque tables could need tuning..torque limits could need tuning...and for all I know fuel pressure dips and knock activity could cause throttle activity to control torque
 
Wow that sounds very confusing lol. So the only thing I know for certain right now that my HPF side should not be tanking the way it is (again only when tuned). My god this is infuriating. What I would do for a set of jets, a carb and an old school Vacuum advance.....


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It varies, the lowest I have seen it is 750psi and that's at 14.5 psi at 4000 rpm.


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Ok that's what I was looking for...that' is on the low side...should be no problem to pull well over 1000psi at that boost and rpm ....
 
Interesting info for those of you trying out "race gas" turns out this fellow also had an issue with his car pulling more fuel in winter due to "winter gas". And this was Arizona winter gas lol. I would love to find out what the value is of our winter gas up here. It's no wonder it's pulling so much more fuel to get to 0.81 Lambda at wot. Or 10.8 Afr. If I understand what he is talking about lol.


kmhamel
Second gear

Join Date: Jul 2009
Location: Healy, Alaska
Posts: 126
I ran across this awhile back, maybe it can be of some use:

Race Gas Stoich Rating Tuning Considerations

Well I have seen questions from time to time about adding race gas without tuning which can be a very expensive experiment. I am going to explain how stoich effects AFR. Hopefully in simple format.

I am not going to get into MAF transfer functions or other tuning functions.This is just about fuel.

First lets define a few terms:

AFR: Air Fuel Ratio

Stoich Rating: In simple terms is the AFR to have chemically complete combustion that is neither rich or lean. For Example most pump gasoline is about 14.64 to 1. Which means 14.7 parts of air to 1 part of fuel.

Lambda: Is a term that is utilized when tuning. In basic terms think of it as an adjustment to your stoich rating when tuning AFR. For example with pump gas tuning .80 lambda, 14.7 x .80 = 11.76 AFR target.

Lets assume your car blower car has a nice tune that gives a perfect 11.8 AFR under WOT with pump gas.

So now it is race day. We add some timing to our tune, drain the fuel tank, and fill up with some high octane unleaded VP109.

We go for a blast down the 1/4 mile while datalogging and see the A/F is reading 12.8 then make a quick trip to the bathroom only to find out they are out of toilet paper -lol.

There are a few factors here to consider.

The stoich rating of VP109 is 13.41.
Most wideband A/F modules are calibrated to 14.7 pump gas stoich.

So this is the formula to determine the true A/F for the run.
AFR/Wideband Stoich x Race Gas Stoich
12.8/14.7*13.41= 11.7 AFR on Race Gas

So you may think 11.7 sounds safe but we must remember the VP109 stoich is 13.41. So 11.7 AFR = .87 lambda. For the most part a safe lambda value is .80 to .82 for a forced induction mustang. I prefer .80

So we take VP109 stoich of 13.41 x .80 lambda = 10.73 AFR
This is the AFR (10.73) I am tuning for.

Keep in mind this is not what will display on your wide band as it is programmed to 14.7 stoich. You must convert the AFR.

AFR/Race Gas Stoich*Wide Band Stoich

10.73/13.41*14.7 = 11.76 AFR is what I want to see on my wideband when running VP109.

Just to reiterate 11.7 on the AFR display with VP 109 is really a 10.7 AFR.

Ok so hopefully you are not totally confused.

There is a simple solution to all of this madness. The SCT Advantage software has a Scalar for Stoichiometric Air Fuel Ratio. You simply enter the correct value for the fuel you are using and all lambda fuel calculations will be based on this value. Then just do the first formula conversion to determine what you should be reading on the AFR display. Some AFR modules may be able to be programed to the correct stoich.

Or leave the stoich in the tune and wideband at 14.64 and calcualte what AFR you need to read on the wideband for the fuel that is used. (This is how I did it in the past, but I find it easier to change the stoich scalar)

This is why you have to exercise caution when mixing race gas and pump gas as you do not know the true stoich of the mixture. The leaded race fuels have a stoich that is closest to pump gas. I always drain my tank before putting in the race gas. When I mixed fuels in the past I didn't notice a drastic change in AFR, but when I have 100% unleaded race gas it really leans out with a 14.64 stoich scalar in the tune.

The other caution is the winter (oxgenated) gas we get in Arizona. I noticed the car leaned out in the winter when it was tuned on the better summer blend. A 14.1 stoich scalar works for the AZ winter gas if your initial tune was based on the summer blend.




Race Gas Stoich Ratings

Sunoco MO2X UL – 14.5
Sunoco 260 GTX – 14.4
Sunoco 260 GT – 13.9
Sunoco 260 GT Plus – 13.7
Sunoco Standard – 14.8
Sunoco Supreme – 14.9
Sunoco MO2X – 14.5
Sunoco HCR Plus – 14.8
Sunoco Maximal – 15.0
Sunoco MaxNOS – 14.9

Turbo Blue Unleaded (100 octane) -13.9
Turbo Blue Unleaded Plus (104 octane) - 13.7
Turbo Blue 110 - 14.7
Turbo Blue Advantage - 14.9
Turbo Blue Extreme - 15.0

VP Street Blaze 100 - 14.16
VP C10 -14.53
VP C16 - 14.77
VP 110 - 15.09
VP MS109 - 13.41


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It doesn't matter what fuel you are using, the ecm is going for a complete burn of 1.

It will add or subtract fuel as necessary to get to 1.

I assure you the fuel you are running isn't causing this issue unless they put E-85 in the wrong tank.

That being said, I've had pretty high percentages of the corn and not seen FRP that low across third.

You would know because your trims would move very high to compensate for the much higher fuel demand.

 
FoMoCoSHO said:
It doesn't matter what fuel you are using, the ecm is going for a complete burn of 1.

It will add or subtract fuel as necessary to get to 1.

I assure you the fuel you are running isn't causing this issue unless they put E-85 in the wrong tank.

That being said, I've had pretty high percentages of the corn and not seen FRP that low across third.

You would know because your trims would move very high to compensate for the much higher fuel demand.
Click to expand...

Wouldn't it also be dependant on the tune also? I am still trying to wrap my head around the whole lambda vs AFR. That said, I am still confused as to the reoccurrence of the same symptoms as last spring. Is there any possibility of the tune in combination with E10 winter gas plus the cold temp be the cause. (It no longer misfired when temps rose above 10C) It might be a stretch but I am getting a feeling of déjà vu. Hence why I am asking and posting quotes.
Also I have been through everything except the HP fuel pump and controller. It does not exhibit anything when the stock tune is loaded. No matter how hard I try.


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Ok so another weird and wacky update. With all of the suggestions and info from my web searches, I decided to do a few things. #1 Installed the 3 bar sensor and 91 V8 tune. I then reset the communication codes in the PCM and reset the adaptive learning through Forscan. To ensure that I had actually reset everything possible I then followed these instructions.

https://youtu.be/hZAsoqmqhdM

And followed his instructions regarding the learning process. Drove the car for about 2 days without doing any crazy WOT blasts and 55 mph pulls. 
After FoMo's and ajp comments I decided to start logging fuel trims and dropped a few other PIDs that were unnecessary for this purpose. As I am trying to limit the total PIds that I am monitoring to keep the connection as quick as possible. So it's 8C today here (it's finally going to warm up later this week lol). Drove the car today a little more aggressively. A few WOT pulls from 0, a few WOT downshifts into second and then finally a few WOT pulls down into 3rd to 4th. It's gone, I mean completely gone. I am still running the same fuel. I can't be happier however I am skeptical that it's truly gone lol. I will continue to be cautious over the next few days just to be safe and datalog any WOT blasts. HPFP no longer drops below 1500 PSI. However I know see the TP1 sensor modulating on a hard WOT downshift. It's not stuck at wide open. I will post a few screenshots of the data logs later showing the HPFP and the trims. 

Any ideas on the results? Could the car actually needed to adapt to the fuel or conditions was there something stuck in the KAM that was contributing? This is over my head, any insight would be great.     
 
So after another frigid day it has not come back, I just realized this topic got to 15 pages. I want to thank you guys for sending me ideas and responding to my posts and questions so quickly. If it was the last set of things that I did that fixed it I have no idea for sure. But I know that some of you SHOdded for one suggested something to do with logic of the fuel control module. And that got me thinking on how to force a reset. I looked through my post from last year. I may have inadvertently done this exact thing. I never did find out what fixed it last year either.   
 
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