Wont start when warm. ?
When cold it starts instantly. After driving around and shut it off..... it wont start again untill it has cooled. Once its cooled awhile (not completely cold) it starts and then idles really low at 400rpms for a few seconds and then slowly comes up to idle at 1100rpms. Then it is fine idling.
Is there a table somewhere that alters somthing based on temp? I zeroed out the IAT table I know the intake pipe gets heat soaked when it sits there off. So that shouldnt be it. ??
Its hard to monitor the A/f when cranking. Not sure how accurate it is since the exh gas is moving so slow thought the pipe. I have 160# high imp injectors. I know that idling around 1100rpms im seeing about 2.5ms injector pulse and that is as low as they go really. A/f at that is about 13.5:1 But when I crank it im seeing inj pulse of like 4.5ms. So I know that its dumping in the fuel. I lean it out in the cranking VE table.. and it wont start at all then or even fire. When its dumping the 4.5ms in it pops and slowly starts when warm sometimes. ... the 400rpms for a few seconds then comes up. Starts fine when cold.
4.5ms seems like a lot of fuel, im not sure if im overlooking some table somewhere??
crazy enough in a stock NA car when the IAT heat-
soaks, on a turbo with the extra heat, ???. Makes
the air calculation way off (low) and the effective
mixture too rich.
Relocating IAT made a big difference for me. May
not be the right thing to do for a turbo SD setup
though. You might want to play with the startup
fueling tables, anything based on IAT you can
find.
crazy enough in a stock NA car when the IAT heat-
soaks, on a turbo with the extra heat, ???. Makes
the air calculation way off (low) and the effective
mixture too rich.
Relocating IAT made a big difference for me. May
not be the right thing to do for a turbo SD setup
though. You might want to play with the startup
fueling tables, anything based on IAT you can
find.
When cold it starts instantly. After driving around and shut it off..... it wont start again untill it has cooled. Once its cooled awhile (not completely cold) it starts and then idles really low at 400rpms for a few seconds and then slowly comes up to idle at 1100rpms. Then it is fine idling.
Is there a table somewhere that alters somthing based on temp? I zeroed out the IAT table I know the intake pipe gets heat soaked when it sits there off. So that shouldnt be it. ??
If you have a wideband O2 in the car and it shows the car running too lean on the hot starts, then adjusting this table closer to 1.0 in the colder cells (and then resetting your VE and base running airflow tables accordingly) should smooth things out.
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If you have a wideband O2 in the car and it shows the car running too lean on the hot starts, then adjusting this table closer to 1.0 in the colder cells (and then resetting your VE and base running airflow tables accordingly) should smooth things out.

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IAT upon trying to start reads 102 degrees. That table is zeroed out anyway. Cant really scan/log a cars starting A/F mixture when it doesnt run.
When its cold it fires instantly, and as it warms up it progressively starts harder. When its semi-warm it fires slowly then idles really low barely wanting to run at like 400rpms.... then after 10 seconds it comes up and idles fine.
Ive played with the afterstart enrichment a lot... no luck... no change. Ive watched my WB go from when its struggling at 400rpms at 10:1 A/F and the same when it says 14:1 ...... So adding subtracting fuel makes no difference... it still idles really low struggling then comes up.. and when its operating temp dont start at all.
Last edited by pwrtrip75; Aug 20, 2011 at 01:46 PM.
richer for cold start. Maybe this is just the wideband indication based on a
gasoline assumption based lambda -> AFR conversion. If so then your
10:1 - 14:1 range of experiment is pig-rich to sorta-rich.
The cranking routines sweep fueling and work the rich to very rich
range. Be sure your hot end of the EQ table does not enrich at your
cranking MAP levels. This can conflict with what you would like for
load / boost. If you can't do without enrichment then cranking fuel
multipliers probably want shaved back (working well cold and not
hot, indicates you're rich). At least these don't bug running AFR,
and you may be able to comp out the EQ table values as they are.
Also when you start it hot, it fires immediately but only runs for 1 second....then nothing. Wont stay running.
richer for cold start. Maybe this is just the wideband indication based on a
gasoline assumption based lambda -> AFR conversion. If so then your
10:1 - 14:1 range of experiment is pig-rich to sorta-rich.
The cranking routines sweep fueling and work the rich to very rich
range. Be sure your hot end of the EQ table does not enrich at your
cranking MAP levels. This can conflict with what you would like for
load / boost. If you can't do without enrichment then cranking fuel
multipliers probably want shaved back (working well cold and not
hot, indicates you're rich). At least these don't bug running AFR,
and you may be able to comp out the EQ table values as they are.
If i can get it running it idles perfect around 13.5:1
I added some to the cranking VE table... it fires faster and instantly, but then drops to like 300rpms for 10 seconds still.
What you wrote that I highlighted in red I am not sure what you mean.
1.00 fuel air multiplier. Cranking MAP is probably 100kPa. I have
seen some tables where high ECT asks for a lot of fuel to keep
ping tamped down, this could hurt cranking.
Also.. would the afterstart enrichment have anything to do w/ it? And if so what is a realistic number to put in that table? I believe it is like .650 now.
Anyone know how do shut the factory alarm off on these? (99 TransAm).
IAT when im trying to start it hot are at 113 degrees, that table is zeroed anyways.
When you turn the key it fires once and doesnt stay running. When its half way warm it fires and idles at like 400rpms for a 20 seconds or so then comes up.
I have adjusted the afterstart enrichment table high and low with no results. Added and subtracted from the cranking VE table... no results.
My tune is attached. Am I overlooking something? A table somewhere?
and it is going to push rich fueling (which cold likes and hot does
not). You might want to begin with making that dovetail with the
main and see what you get.I'd scale the whole thing until the 400,
800, 1200 columns agree (which is a fait bit of shaving, 70s -> 50s).
Your Charge Bias temp table is way off from stock and it biased
toward IAT at low flows, ECT bias (larger fraction) may be more
realistic. If "hot start" ECT is greater than IAT then ECT bias will
lean out the cranking.
Last edited by pwrtrip75; Oct 30, 2011 at 06:02 PM.

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