Help! Car wont go into Decel DFCO
Thread Starter
TECH Apprentice
Joined: Apr 2002
Posts: 308
Likes: 0
From: Austin, TX
Help! Car wont go into Decel DFCO I've been having trouble with my idle. It works fine for a few days after a flash... but then it goes to crap after about 3 days of driving. I don't even know if idle is the right word for what I'm describing. The problems are more in the approach to idle and the stumbling that follows. Once the car sits in the actual idle cell (19), it is pretty smooth.
This has been driving me absolutely nuts
I think I have it all worked out and then I suddenly can hardly keep it from stalling. I usually just disconnect the batt for a few minutes and the problem is solved.
Anyway, I finally noticed that the car never goes into the Decel fuel trim cell and that decel situations are jacking up my fuel trim cells.
I'm not sure if this is my problem, but I think it is a clue/related.
My cam is a blower cam, so it is not big at all. Something in the 224 115 range.
I looked at the Decel tables in ls1edit and the one for Decel speed makes no sense.
it has MAP values of 65 - 105 on the x axes and MPH on the Y with 28 in each cell. How the heck could the car ever see 65 KPA on decel. The MPH is the only value I can change. The other tables just have RPM in them .
Any ideas?
Do you guys see the Decel trim cell regularly on your cars? If so, can you post up the conditions where you see it (MAP, MPH, TPS)
BTW, this a c5 (fly by wire) if that makes any difference.
This has been driving me absolutely nuts
I think I have it all worked out and then I suddenly can hardly keep it from stalling. I usually just disconnect the batt for a few minutes and the problem is solved. Anyway, I finally noticed that the car never goes into the Decel fuel trim cell and that decel situations are jacking up my fuel trim cells.
I'm not sure if this is my problem, but I think it is a clue/related.
My cam is a blower cam, so it is not big at all. Something in the 224 115 range.
I looked at the Decel tables in ls1edit and the one for Decel speed makes no sense.
it has MAP values of 65 - 105 on the x axes and MPH on the Y with 28 in each cell. How the heck could the car ever see 65 KPA on decel. The MPH is the only value I can change. The other tables just have RPM in them .
Any ideas?
Do you guys see the Decel trim cell regularly on your cars? If so, can you post up the conditions where you see it (MAP, MPH, TPS)
BTW, this a c5 (fly by wire) if that makes any difference.
Thread Starter
TECH Apprentice
Joined: Apr 2002
Posts: 308
Likes: 0
From: Austin, TX
scratch some of the above. It is going into decel (cell 21) I just did another scan and it gets there at about 30kpa (sometimes). I have to really jam it into a low gear and decel hard with the motor to see the cell (is that what happens on a stock car?). So I guess that table is based on vacuum (100kpa = 0map) meaning ~40map is required to hit fuel cutoff.
Something is still wrong though. I see a few data points where my STFT is going absolutely nuts (like 50%). Im in FTC 2 at 22map, 60mph, 8.6tps, 1900 rpms ( I think that was letting off the gas in 5th). It is sticking in cell 2 and really screwing up my trims. Could be a o2 sensor that needs more heat, I have 32 primaries on my long tubes .. use the rear o2s in the front o2 position.
Anyway, any ideas on fixing this would be greatly appreciated. Again, the symptoms are (runs fine for a few days after flash/batt disconnect), then goes in the crapper at idle conditions.
Something is still wrong though. I see a few data points where my STFT is going absolutely nuts (like 50%). Im in FTC 2 at 22map, 60mph, 8.6tps, 1900 rpms ( I think that was letting off the gas in 5th). It is sticking in cell 2 and really screwing up my trims. Could be a o2 sensor that needs more heat, I have 32 primaries on my long tubes .. use the rear o2s in the front o2 position.
Anyway, any ideas on fixing this would be greatly appreciated. Again, the symptoms are (runs fine for a few days after flash/batt disconnect), then goes in the crapper at idle conditions.
Very rarely do I ever see fuel shutoff. Its really designed to protect the catalytics during a long coast period of lean running. You'd have to be doing some heavy engine breaking to see the fuel shutoff, or coasting down a mountain. As far as why the car is idling/decelling strangely...not sure
Thread Starter
TECH Apprentice
Joined: Apr 2002
Posts: 308
Likes: 0
From: Austin, TX
Originally Posted by MyLS1Hauls
Very rarely do I ever see fuel shutoff. Its really designed to protect the catalytics during a long coast period of lean running. You'd have to be doing some heavy engine breaking to see the fuel shutoff, or coasting down a mountain. As far as why the car is idling/decelling strangely...not sure
I have a feeling my 02 sensors are playing games with me.
TECH Addict
Joined: Sep 2003
Posts: 2,065
Likes: 0
From: Atlanta, GA
my cam decels from 41-55 KPA. my idle is 1000 due to not wanting to stall with a/c etc.
the tables which i assume are stock have
map entry 18kpa
map exit 29 kpa
rpm 900/1500
so what ya want to do get a buddy to watch the decel range or log it, and then move the map entry and exit point up. equally at first.
say in my case i would probably +5 map entry & map exit 1-3 times (try each) and then alter the rpm point to match my idle and things would work again.
might try it later, helps to have 4 hands when logging, that way they can log and analyze and do the new map while you drive, then pull over, flash in 30 seconds (hptuners!) and test a new program.
by yourself, i suggest staging 4-5 programs then run #1 , pull over in neighborhood, flash, run #2, etc. thats how i solo-tune.
good luck. let us know how that works
+5 on map entry and map exit until something changes
the tables which i assume are stock have
map entry 18kpa
map exit 29 kpa
rpm 900/1500
so what ya want to do get a buddy to watch the decel range or log it, and then move the map entry and exit point up. equally at first.
say in my case i would probably +5 map entry & map exit 1-3 times (try each) and then alter the rpm point to match my idle and things would work again.
might try it later, helps to have 4 hands when logging, that way they can log and analyze and do the new map while you drive, then pull over, flash in 30 seconds (hptuners!) and test a new program.
by yourself, i suggest staging 4-5 programs then run #1 , pull over in neighborhood, flash, run #2, etc. thats how i solo-tune.
good luck. let us know how that works
+5 on map entry and map exit until something changes
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Thread Starter
TECH Apprentice
Joined: Apr 2002
Posts: 308
Likes: 0
From: Austin, TX
Originally Posted by samz28
my cam decels from 41-55 KPA. my idle is 1000 due to not wanting to stall with a/c etc.
the tables which i assume are stock have
map entry 18kpa
map exit 29 kpa
rpm 900/1500
so what ya want to do get a buddy to watch the decel range or log it, and then move the map entry and exit point up. equally at first.
say in my case i would probably +5 map entry & map exit 1-3 times (try each) and then alter the rpm point to match my idle and things would work again.
might try it later, helps to have 4 hands when logging, that way they can log and analyze and do the new map while you drive, then pull over, flash in 30 seconds (hptuners!) and test a new program.
by yourself, i suggest staging 4-5 programs then run #1 , pull over in neighborhood, flash, run #2, etc. thats how i solo-tune.
good luck. let us know how that works
+5 on map entry and map exit until something changes
the tables which i assume are stock have
map entry 18kpa
map exit 29 kpa
rpm 900/1500
so what ya want to do get a buddy to watch the decel range or log it, and then move the map entry and exit point up. equally at first.
say in my case i would probably +5 map entry & map exit 1-3 times (try each) and then alter the rpm point to match my idle and things would work again.
might try it later, helps to have 4 hands when logging, that way they can log and analyze and do the new map while you drive, then pull over, flash in 30 seconds (hptuners!) and test a new program.
by yourself, i suggest staging 4-5 programs then run #1 , pull over in neighborhood, flash, run #2, etc. thats how i solo-tune.
good luck. let us know how that works
+5 on map entry and map exit until something changes
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Brett Foote TECH Addict
Joined: Sep 2003
Posts: 2,065
Likes: 0
From: Atlanta, GA
Originally Posted by QuickSilver2002
I have ls1-edit and have no ability to change MAP entry/exit. It only exposes RPM and speed values in all of the DFCO related tables.
Thread Starter
TECH Apprentice
Joined: Apr 2002
Posts: 308
Likes: 0
From: Austin, TX
Originally Posted by samz28
well sounds like you need a new tuner software
FWIW, I logged a friends stock z06 and it goes into DFCO pretty darn easy. I'm thinking DFCO is for way more than just kepping the cats happy. I like the idea of having decel in it's own cell. Now I just need to figure out what those tables in edit really mean.
Anyone here worked with the DFCO tables in edit?
