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Suddenly cant reach full timing - Can anyone check these logs?

ahl395

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Hey guys,

Not sure how long it's been going on exactly but suddenly it seems I can't reach full timing advance anymore. Before I pay Lund to look my logs over again I figured I'd see if anyone here could take a look or give me some pointers.

Previously I ran 20-21 degrees of timing all the way to redline. Now it seems stuck at 15 most of the time and the highest I've seen is 17-18 degrees. Inconsistent sometimes too where before it was pretty steady.

Thing I have done so far trying to fix:
Changed plugs, Brisk RR12S Two heat ranges colder gapped to .026
Reloaded tune
KAM reset by disconnecting battery
Checked for false knock
Checked meth system
Many different tanks of gas

Three logs attached in the zip. "WOT 3rd dual nozzle" is my old log when everything was working correctly. The other two are what I'm currently seeing.

Thanks in advance if anyone can shed some light on it for me.
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Jay-rod427

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Not really sure, but the knock sensors aren't really wanting to add much more than it's getting. Could just be winter blend fuel not happy even with meth
 

markmurfie

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I would replace your battery with a new one. I've had to replace mine one every two years. Weak batterys can work, but cause small issues only few people would notice. May not be the issue could be an octane thing, but alternator output changed between good and bad. Fuel trims are following the voltage change which could be alternator or battery, causing the issue. Its pretty amazing how sensitive these new cars can be with seemingly small voltage changes. That being said you would think the high fuel demand and the high efficiency(heavy charging duty) output table would be the same on an oem tune, to avoid any differences from going WOT when the battery is a little low, avoiding any voltage drop, but they are not. In nearly all other situations voltage would not change or it would go up.

On a side note, that MAF placement would drive me nuts if this was my car. Spoiled looking at PD logs.
 
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BadGTR

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I ran 20 degrees with a e85 tune on the dyno. When I did a street pull my timing was 4 degrees lower after the first shift and thru the rest of the pull in all gears. Was told it was due to traction and torque limits. Tuner said he could turn all torque limits off. Uh yeah..... that's what I expected from the original tune. Maybe your having a similar issue?
 

sigintel

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Bad fuel, bad pump, bad battery can get you marginal behavior.

Had bad battery issue w Whipple and in rare circumstance with lights on during first 30 min driving the voltage at extended WOT seemed unstable.
Alternator/voltage regulator may dynamically “back off” of the higher voltage charge cycle at high rpm and was changing fuel pump voltage faster than short term trim reactions leading to leaner than desired with pump near max.
Not saying thats your problem.

Details if needed:
Fuel Volume and Pressure require Power.
Pump Power = Volume x Pressure
Equation example w constants:
https://www.engineeringtoolbox.com/pumps-power-d_505.html

The electric motor driving the pump:
Power = (V^2) / R
https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/calculating-electric-power/
Technically theres something called back EMF but the point is simple:
Electric pump power capability changes with the SQUARE of the voltage, so rapid drop of 25% voltage drops 50% pump power available on shaft.

Are you on a voltage booster for the pump?
If so, dont expect pump to last 100k miles.
 

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Tommy V

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If it turns out not being battery ,put a can octanium in your tank and re log still using your meth to see if it is a fuel issue.
 

kcc0521

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I would bet it is a very slim chance the battery is the issue. When did it start? What is the last thing you changed on the car?
 

markmurfie

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When you look at logs and fuel trims, they should be consistently the same pattern at the same values, through the RPMs at WOT. In your log 1 vs old good log you can see this pattern in both 3rd gear pulls and the fourth gear part of the bad log. Comparing yours, it starts out lean, with a spike, That's never good and prone to causing knock. Your voltage drop correlates directly with this lean spike. After 4-5 seconds and it gets into fourth trims have returned to almost normal, but still higher than your older log. My guess is the voltage is affecting your meth pump more than your fuel pump. Either way you want voltage consistent for the sake of all the control systems.

If its not the battery, I would make sure everything about your alcohol spray kit is functioning correctly. Since that is what you are depending on instead of octane of the fuel. The change in FTs during one pull kinda indicates its not flowing consistently.
New vs old FTs.PNG
 

yote41

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I will second the battery.i was only seeing 14-15 after jumping my car few times this winter. Got new battery and back at 17
 

sigintel

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The change in FTs during one pull kinda indicates its not flowing consistently.
New vs old FTs.PNG
Love the markmurfie detailed eval and post.
Looking forward to next log after battery is changed and meth pump filter changed out.

Side question: on meth systems, do yall mix in small quantities of lubricant similar to that added to pump gas to meet lubricity requirements for pump durability?
Have seen synthetic aviation grade two stroke oil added to high fraction toluene mix to avoid pump issues. Relevant or nah?
 

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markmurfie

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Side question: on meth systems, do yall mix in small quantities of lubricant similar to that added to pump gas to meet lubricity requirements for pump durability?
Have seen synthetic aviation grade two stroke oil added to high fraction toluene mix to avoid pump issues. Relevant or nah?
Stick to 50/50 100%methanol/ 100%water, no lubricants, additives, or minerals in the water and your pump should be fine for a long time.
 
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ahl395

ahl395

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Thanks guys for all the replies! Much appreciated.

So some more info:

I will have to check it over but I would be very surprised if it was the charging system since mine is heavily upgraded. Battery is probably only a year and a half old and it is an AGM type, beefier than the standard. Also have a high output alternator (380A instead of factory 220A) and all the smart battery charging stuff is bypassed it runs at the full 14.7-15.0V. These upgrades are done for my heavy duty sound system but that is always turned off when doing logs. Same exact system in both logs too.

I did consider the winter blend being an issue but figured the meth would overcome that. However I think this may be the issue!! I put a can of torco in with my 93 and I saw it slowly climb from 16 to 20 during several pulls. It used to be a much quicker change to 20-21, but I was happy to see it anyway. A few times it still did get dead stuck on 15 though too. So very strange that it's so inconsistent. Seems like it just gets stuck on 15 and knock sensors do nothing at all. Wondering if false knock could be at play here too.

Nonetheless, I was able to pull 20 degrees on several pulls with the torco. So I'm thinking winter blend gas plus some false knock mixed in may be the problem. Going to try turning up the meth a bit more to see if I can offset the crap gas.


On a side note, that MAF placement would drive me nuts if this was my car. Spoiled looking at PD logs.
I asked Lund if it would be better to move the MAF to the pipe when I put the gate on the intercooler but they advised against it said the pipe would make it harder to tune drivability wise.

I ran 20 degrees with a e85 tune on the dyno. When I did a street pull my timing was 4 degrees lower after the first shift and thru the rest of the pull in all gears. Was told it was due to traction and torque limits. Tuner said he could turn all torque limits off. Uh yeah..... that's what I expected from the original tune. Maybe your having a similar issue?
This could be. On my old log torque limiting and all that was turned off. Now it is turned back on after several transmissions breaking.

Bad fuel, bad pump, bad battery can get you marginal behavior.

Had bad battery issue w Whipple and in rare circumstance with lights on during first 30 min driving the voltage at extended WOT seemed unstable.
Alternator/voltage regulator may dynamically “back off” of the higher voltage charge cycle at high rpm and was changing fuel pump voltage faster than short term trim reactions leading to leaner than desired with pump near max.
Not saying thats your problem.

Details if needed:
Fuel Volume and Pressure require Power.
Pump Power = Volume x Pressure
Equation example w constants:
https://www.engineeringtoolbox.com/pumps-power-d_505.html

The electric motor driving the pump:
Power = (V^2) / R
https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/calculating-electric-power/
Technically theres something called back EMF but the point is simple:
Electric pump power capability changes with the SQUARE of the voltage, so rapid drop of 25% voltage drops 50% pump power available on shaft.

Are you on a voltage booster for the pump?
If so, dont expect pump to last 100k miles.
Yes the pump is on a voltage booster, throttle referenced.

When the pump goes bad, pressure will drop assumably. I do have a fuel pressure gauge and it stays above 40psi at all times.

If it turns out not being battery ,put a can octanium in your tank and re log still using your meth to see if it is a fuel issue.
Judging by me watching the ngauge this mostly fixed it, I will have to take some logs to check

I would bet it is a very slim chance the battery is the issue. When did it start? What is the last thing you changed on the car?
Last thing I changed was I added a solenoid on the meth system but the issue could have started before then, not sure. Maybe the solenoid in line reduces the flow some. Again going to try upping the meth.

Love the markmurfie detailed eval and post.
Looking forward to next log after battery is changed and meth pump filter changed out.

Side question: on meth systems, do yall mix in small quantities of lubricant similar to that added to pump gas to meet lubricity requirements for pump durability?
Have seen synthetic aviation grade two stroke oil added to high fraction toluene mix to avoid pump issues. Relevant or nah?
Stick to 50/50 100%methanol/ 100%water, no lubricants, additives, or minerals in the water and your pump should be fine for a long time.
Yep no additives or anything. Just straight meth and distilled water. The pump seals will eventually go bad and start to leak and I'll need to rebuild it.
 

Jay-rod427

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FWIW Lund had to desensitize my knock sensors slightly. Jon Jr said it's pretty common on blower cars due to picking up blower vibes. But mine was horrible like barely roll into the throttle and it would pull timing down to 8 degrees, then next pull would be fine. Now it's happy as can be. Knock sensors still add a few degrees as they see fit. I'm seeing 22-23 degrees on E85.
 
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ahl395

ahl395

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FWIW Lund had to desensitize my knock sensors slightly. Jon Jr said it's pretty common on blower cars due to picking up blower vibes. But mine was horrible like barely roll into the throttle and it would pull timing down to 8 degrees, then next pull would be fine. Now it's happy as can be. Knock sensors still add a few degrees as they see fit. I'm seeing 22-23 degrees on E85.
I may request this too as this isnt the first time I've had a problem with false knock.
 

markmurfie

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If you say octane booster helped, but your planning on ignoring the knock, I hope this doesn't turn into a compression check/ leak down results thread.
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