Tuning warning
07-11-2007, 09:15 PM
#1
Tuning warning For the new tuners that might not know.Watch out how you tune in this hot weather. Cars can take lot more timing due to poor air quality.The side affect is when the weather cools down the engine's start to detinate.This is a huge problem with FI cars.You see alot of these cars tuned in the hot months then blow #7 piston in the fall.
Just a heads up
Just a heads up
07-11-2007, 09:20 PM
#3
Originally Posted by Slowhawk
For the new tuners that might not know.Watch out how you tune in this hot weather. Cars can take lot more timing due to poor air quality.The side affect is when the weather cools down the engine's start to detinate.This is a huge problem with FI cars.You see alot of these cars tuned in the hot months then blow #7 piston in the fall.
Just a heads up
Just a heads up
07-11-2007, 09:45 PM
#4
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thanks for the info i was just concidering adding little timing since im not getting any detonation. so would you recommend adding timing when it cools down ,i was told it was easier to tune in the winter, i guess that was more bad info i got from old mechanic
Good word of warning!
07-12-2007, 04:43 AM
#6
I played with a car yesterday that I know only likes 26 degree's of timing in the cool weather.It was 94 degree's out and I ran 32 degree's of timing on it without any KR 
HP stayed the same as 26 degree's. Of course we put it back after.
FI cars are famous. We get a ton of blown up Mustangs in the fall and ussually 2-3 LS1's. All ussually have too much timing from being tuned in the heat.Atleast the shops around here keep us busy
HP stayed the same as 26 degree's. Of course we put it back after.FI cars are famous. We get a ton of blown up Mustangs in the fall and ussually 2-3 LS1's. All ussually have too much timing from being tuned in the heat.Atleast the shops around here keep us busy
07-12-2007, 07:10 AM
#7
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I've always heard/experienced that the hotter/warmer weather is when we'll see KR and can't run as much timing...
in the winter/cooler weather though, the air is MORE dense, thus resulting in a better air charge, sucking in more air and we can increase timing/spark.
This has been my experience anyway...
in the winter/cooler weather though, the air is MORE dense, thus resulting in a better air charge, sucking in more air and we can increase timing/spark.
This has been my experience anyway...
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Last edited by 06MonteSS; 07-12-2007 at 07:38 AM.
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07-12-2007, 02:02 PM
#8
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Originally Posted by 06MonteSS
I've always heard/experienced that the hotter/warmer weather is when we'll see KR and can't run as much timing...
in the winter/cooler weather though, the air is MORE dense, thus resulting in a better air charge, sucking in more air and we can increase timing/spark.
This has been my experience anyway...
in the winter/cooler weather though, the air is MORE dense, thus resulting in a better air charge, sucking in more air and we can increase timing/spark.
This has been my experience anyway...
Hot air leaner , Cold air richer as far as AFR goes , phatter AFR more timing .
???????
Last edited by HD6.0l; 07-12-2007 at 02:27 PM.
07-12-2007, 02:18 PM
#9
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actually, colder air should make you leaner shouldn't it? since it's more dense, you're pulling/sucking in MORE air....
hotter air is less dense, therefore less air is coming in, making it run richer... no??
hotter air is less dense, therefore less air is coming in, making it run richer... no??
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07-12-2007, 02:34 PM
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No , I have watched with wideband and colder air seems to run richer AFRs , at the track a guy had his car Dynoed that day at 80* and was running 11.5 AFR at the track that night he was running 10.8 AFR @ 55* .
07-12-2007, 02:47 PM
#11
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aaah, ok... makes sense now that I think about it...
colder, more dense air means we're pulling in more air by volume, so the ECM adds more fuel to keep the AFR in check...
warmer, less dense air means we're pulling in less air by volume, so the ECM subtracts fuel...
gotcha...
thx!
EDIT: but then, how could the issue mentioned in post #1 happen then? if you tune in the hotter weather, then when it gets colder the AFR should go richer - so why would that blow the engine?? I could see if it went leaner when it got colder, but what we're saying here is that it gets richer when it gets colder... Hmmm...
colder, more dense air means we're pulling in more air by volume, so the ECM adds more fuel to keep the AFR in check...
warmer, less dense air means we're pulling in less air by volume, so the ECM subtracts fuel...
gotcha...
thx!
EDIT: but then, how could the issue mentioned in post #1 happen then? if you tune in the hotter weather, then when it gets colder the AFR should go richer - so why would that blow the engine?? I could see if it went leaner when it got colder, but what we're saying here is that it gets richer when it gets colder... Hmmm...
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Last edited by 06MonteSS; 07-12-2007 at 02:52 PM.
07-12-2007, 04:42 PM
#12
Originally Posted by 06MonteSS
EDIT: but then, how could the issue mentioned in post #1 happen then? if you tune in the hotter weather, then when it gets colder the AFR should go richer - so why would that blow the engine?? I could see if it went leaner when it got colder, but what we're saying here is that it gets richer when it gets colder... Hmmm...
The change is more drastic on FI cars.Most people here deal with there own cars.I'm lucky enough to tune a ton of cars and see the difference.
07-12-2007, 07:03 PM
#13
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You can put more charge into the motor when the air
is denser.
With more charge in it, you would really like to not
light it off in a place where it can't easily expand
into work delivered to the crank. Your motor might
tolerate early ignition (after TDC, but away from
best crank angle) if it's a punk charge but break
something at a higher charge that has nowhere to
go (for a few tens of crank degrees ATDC, cylinder
volume changes not much, so pressure and temp
must remain high and the aluminum doesn't really
like either one). You want peak pressure to develop
around peak leverage angle I believe. Not early and
not late. Early breaks stuff, late burns stuff.
None of this has to do with mixture really. Though
you could add problems that way.
is denser.
With more charge in it, you would really like to not
light it off in a place where it can't easily expand
into work delivered to the crank. Your motor might
tolerate early ignition (after TDC, but away from
best crank angle) if it's a punk charge but break
something at a higher charge that has nowhere to
go (for a few tens of crank degrees ATDC, cylinder
volume changes not much, so pressure and temp
must remain high and the aluminum doesn't really
like either one). You want peak pressure to develop
around peak leverage angle I believe. Not early and
not late. Early breaks stuff, late burns stuff.
None of this has to do with mixture really. Though
you could add problems that way.
07-12-2007, 07:43 PM
#14
Originally Posted by jimmyblue
You can put more charge into the motor when the air
is denser.
With more charge in it, you would really like to not
light it off in a place where it can't easily expand
into work delivered to the crank. Your motor might
tolerate early ignition (after TDC, but away from
best crank angle) if it's a punk charge but break
something at a higher charge that has nowhere to
go (for a few tens of crank degrees ATDC, cylinder
volume changes not much, so pressure and temp
must remain high and the aluminum doesn't really
like either one). You want peak pressure to develop
around peak leverage angle I believe. Not early and
not late. Early breaks stuff, late burns stuff.
None of this has to do with mixture really. Though
you could add problems that way.
is denser.
With more charge in it, you would really like to not
light it off in a place where it can't easily expand
into work delivered to the crank. Your motor might
tolerate early ignition (after TDC, but away from
best crank angle) if it's a punk charge but break
something at a higher charge that has nowhere to
go (for a few tens of crank degrees ATDC, cylinder
volume changes not much, so pressure and temp
must remain high and the aluminum doesn't really
like either one). You want peak pressure to develop
around peak leverage angle I believe. Not early and
not late. Early breaks stuff, late burns stuff.
None of this has to do with mixture really. Though
you could add problems that way.
Just messing with ya
07-12-2007, 08:35 PM
#15
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Slowhawk I am gonna be running 9lbs of boost in my car. It is getting tuned down in Southeast Florida in about a week and a half hopefully. Obviously it is summer here and will be tuned for the weather accordingly. Now should I also have it retuned in the winter months here as well? It doesn't get that cold here at all usually in the winter. If it does it may be for no longer than a week at a time usually, and by no means is it cold compared to where you are located. What are your thoughts? I appreciate any advice you can throw my way.
07-12-2007, 10:41 PM
#16
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Originally Posted by Slowhawk
Tune your car in the hot weather and see what happens in the cold weather The change is more drastic on FI cars.Most people here deal with there own cars.I'm lucky enough to tune a ton of cars and see the difference.
The change is more drastic on FI cars.Most people here deal with there own cars.I'm lucky enough to tune a ton of cars and see the difference.geez....
rough day??!!
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07-13-2007, 12:44 AM
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None of this really makes any sense.
If your sensors are reporting correctly & you have tuned properly for the variations then your AFR shouldnt change. Only if your sensors are giving bad info like with heatsoak not giving an accurate description of air temp should you have an issue.
I realise it isnt a perfect world but from what Ive seen in my car from an early morning log with the ambient air being around 0 degC to an afternoon temp of 28 degC is less than 1% variation on my Ben Maps. Not an engine destroying scenario.
If your sensors are reporting correctly & you have tuned properly for the variations then your AFR shouldnt change. Only if your sensors are giving bad info like with heatsoak not giving an accurate description of air temp should you have an issue.
I realise it isnt a perfect world but from what Ive seen in my car from an early morning log with the ambient air being around 0 degC to an afternoon temp of 28 degC is less than 1% variation on my Ben Maps. Not an engine destroying scenario.
07-13-2007, 08:33 AM
#18
TECH Senior Member
^^^but if you're running alot more timing due to tuning in warm weather... when it gets cold that timing is overkill and potentially dangerous (especially for FI instances)
I suppose you could use the IAT timing modifier table to account for changes.. however there's no reason to run more timing than you need... (no reason to run 35* when running 26* makes the same power)
I suppose you could use the IAT timing modifier table to account for changes.. however there's no reason to run more timing than you need... (no reason to run 35* when running 26* makes the same power)
07-13-2007, 09:12 AM
#19
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Yep...I agree...
On the GTP in say 30* weather I can see as much as 1-1.5 psi more boost than in say 70* weather. That extra boost, even though its a colder charge, makes KR more likely. Gotta be way conservative on timing...
One thing does the LS1 PCM have a table to adjust spark based on AFR? The GTP does and for some reason it adds timing when the A/F gets richer. So colder often makes the WOT AFR richer and then adds timing on top.....
On the GTP in say 30* weather I can see as much as 1-1.5 psi more boost than in say 70* weather. That extra boost, even though its a colder charge, makes KR more likely. Gotta be way conservative on timing...
One thing does the LS1 PCM have a table to adjust spark based on AFR? The GTP does and for some reason it adds timing when the A/F gets richer. So colder often makes the WOT AFR richer and then adds timing on top.....
