cold start issue 05 gto

[mustangt66351]

i am having a hard time starting my gto when it is below freezing. it will start fine in warmer temps and after sitting for several hours. if i leave it sit overnight and get fully cold it will fire and die right out. then i have a crank no start until i put it to wot. if i pedal it just right i can get it to fire and hold the rpms until it will stay running. the car runs and idles perfect and was tuned at a shop. i originally had bought most of my mods from my friend and used his tune. he also had this issue and spoke with the tuner to help resolve this but never got to it since he sold me his entire setup. i have searched multiple threads and forums and cannot find a definite answer on how to tune this. which tables need to be modified? 05 a4 gto ls2, mods as follows, 231 238 .617 .615 113 pat g cam, lightly ported 243s, awespeed intake with fast acting iat sensor, pacesetter long tubes no cats and cutouts, slp lm2 catback, fti 3600 stall converter. i dont have a tune on me at the moment to post but will soon. any help would be appreciated this is my first post and new to tuning and the forum.

[schpenxel]

i am having a hard time starting my gto when it is below freezing. it will start fine in warmer temps and after sitting for several hours. if i leave it sit overnight and get fully cold it will fire and die right out. then i have a crank no start until i put it to wot. if i pedal it just right i can get it to fire and hold the rpms until it will stay running. the car runs and idles perfect and was tuned at a shop. i originally had bought most of my mods from my friend and used his tune. he also had this issue and spoke with the tuner to help resolve this but never got to it since he sold me his entire setup. i have searched multiple threads and forums and cannot find a definite answer on how to tune this. which tables need to be modified? 05 a4 gto ls2, mods as follows, 231 238 .617 .615 113 pat g cam, lightly ported 243s, awespeed intake with fast acting iat sensor, pacesetter long tubes no cats and cutouts, slp lm2 catback, fti 3600 stall converter. i dont have a tune on me at the moment to post but will soon. any help would be appreciated this is my first post and new to tuning and the forum.

Post a log of it happening. Get VCM Scanner recording before you try to start the car the first time.

Post the tune used

No one can help you without that

[mustangt66351]

vics setup and trans mods for stall corrected 2.hpt

heres the current tune.
i will be able to get a cranking event log this evening.

[mustangt66351]

Which histograms do i need to log while cranking?

[schpenxel]

Which histograms do i need to log while cranking?

Histograms don't pick what is being logged. You can make those later based on what PID's you have data recorded for

What you have in the "table display" window defines what you are recording

So

Off the top of my head the ones that come to mind are:
RPM
MAF (hz)
MAF airflow
injector pulsewidth bank 1
injector pulsewidth bank 2
Ignition voltage
Manifold absolute pressure (MAP)
Commanded EQ ratio
Throttle position
and if you have a wideband, log that too
And if there's anything else in there, just leave it in

[mustangt66351]

here are the logs

bad crank.hpl
floored it to start and idles after.hpl
idle cold.hpl

first is attempting cold start but no success. i cranked several times to get a definitive reading
second attempt i held the pedal to almost wot to get to fire and idle
third is just an idle segment cold after all these events

[schpenxel]

Mine did the same thing when I had the same problem.. injector PW is really high when cranking on the first log. I'll look through the tune and other logs in a bit

Can you smell gas on the tries when it doesn't start?

I found on mine I could pull the fuel pump fuse and it would start, lol

Also, you didn't log commanded EQ ratio

[mustangt66351]

yes i smell gas.
thanks
how do i set up pid for eq ratio?
i can get another log tomorrow morning.

[schpenxel]

I had a chance to compare the tune you posted to a stock 05 GTO file

There isn't a whole heck of a lot changed that should matter for this in my opinion.

The one thing I do see that I would change back is the startup airflow. It's under idle-->Airflow-->Startup. It looks like those were increased by about 50%. If it's dumping too much fuel in, it seems like this could help

There are also some spots of the airflow final minimum table that have been pushed up quite a bit. May be needed due to your cam, but that may be something to mess with if the startup airflow adjustments don't help

Cranking VE has been changed from 100% to 85%. I doubt that is the cause.. if anything that should make it inject less fuel, not more

Attached is a stock GTO file I got off the HP Tuners repository. I can't guarantee it's really a stock file, but whoever posted it said that it was.

----

So, here is what I would try

-Install absolute latest version of HP Tuners (download from the latest daily release and re-install)
-Change startup airflow back to stock values, or at least cut the difference in half
-Do a FULL write
-Log the next cold start attempt and see what happens.

2005 GTO Stock Tune.hpt

You are the third person (including myself) to have this issue.. so that is why I say reinstall the latest version and do a complete write first.

[schpenxel]

yes i smell gas.
thanks
how do i set up pid for eq ratio?
i can get another log tomorrow morning.

There is already one setup.. you just have to add it to the table. It'll probably be called Commanded EQ ratio or something like that.. it may be a good bit down the list

[mustangt66351]

There is already one setup.. you just have to add it to the table. It'll probably be called Commanded EQ ratio or something like that.. it may be a good bit down the list

thanks alot i appreciate your help. i tried to use the commanded eq ratio histogram and its its not supported. i also tried to put it on the charts with no luck.do you have a config file that i can use with supported pids histos and charts? i tried to download several peoples and insert them or load them. some work some dont.

i still have my stock tune available to compare. i will make sure i have the latest hptuners on there. i will adjust the variable you provided and get back with you tomorrow hopefully. i also play with the cranking ve up and down with no changes so yea i dont think thats messing with anything.

again thank you for everything!

[mustangt66351]

i have 2.24.954 version currently

[schpenxel]

thanks alot i appreciate your help. i tried to use the commanded eq ratio histogram and its its not supported. i also tried to put it on the charts with no luck.do you have a config file that i can use with supported pids histos and charts? i tried to download several peoples and insert them or load them. some work some dont.

The histogram view does not matter as it does not control what is being logged.. The only thing that matters right now is what you have listed in the "table display" window. Completely forget about histograms or whatever you are trying to load from there as they will not work if the right parameters are not being logged in the first place

The table view is where you need to add it.. just right click on an empty spot in that window and go to insert.. in the window that pops up go under fuel system and double click commanded EQ ratio. That should add it to the table display.

[mustangt66351]

i updated to 2.24.1030. i get off at 5pm and will modify it then and reinstall. i will do the charts that im pretty sure i tried it but will do again. i dont think it was displaying anything. i could be wrong.

[mustangt66351]

update. i changed the startup airflow and got better starting but died after few seconds. i changed the final airflow minimum to lower numbers at under 800 rpm in park and neutral. now its starts great everytime it sits for a day. thanks alot for your help schpenxel.

[schpenxel]

update. i changed the startup airflow and got better starting but died after few seconds. i changed the final airflow minimum to lower numbers at under 800 rpm in park and neutral. now its starts great everytime it sits for a day. thanks alot for your help schpenxel.

Good deal! Don't feel like I helped much.. but if the problem is fixed, that is all that really matters.