Runs Good - Need Startup Help

[Eticket]

Hey guys,

My car actually runs and drives great on a Seq Fast, but I have a consistent start up problem.

When the car is fresh and cold, overnight, it cranks and cranks and finally starts, then quickly dies. This happens almost exactly 3 times and then the car will start and find idle. I have to let it idle for a minute or so before I can drive it. When I do try to drive it just after a start, it will have tip in stumble and try to die.

Now, when the car is relatively warm, it starts ok (less cranking) and doesn't take multiple cranks to get it started.

Any ideas on where I should start to adjust? Should I fatten up the startup fuel? I'm open to any and all suggestions. I know that a good tuner can fix this, but I can't really leave my car at his house or shop.. just don't like that idea.

Thanks,
John

I would be very greatful to look at anyone else's programs for 27X inch stage II champion headed cars with 83 lbers.

 

[norbs]

This is a very complicated situation. YOu need to work between afterstart, afterstart decay rates, coolant temp correction and cranking fuel and iac starting position, or it will drive you up the wall.


Step 1. do one change at a time. and your ve table should be set warm engine to be the best numbers for almost perfect o2 correction and set timing for starting no more than 20 degrees.

Step 2. add cranking fuel at the temperature your having trouble starting at until it kicks right away, but it still might not start. You will know if its too much as it will buck and not sound right. If it kicks right away and stalls stop adding fuel!
So do this in small steps

Step 3 increase the afterstart fueling for that temperature your having trouble with. Remember afterstart is short term enrichment and coolant temp enrichment is long term enrichment. You can log this during a cold start, log afterstart, coolant enrichment, actual a/f, iac position.
You should expect to see low 11'sa/f for the first 10 seconds of operation then mid then 12' then high 12s as the car warms gradually. By logging this you can see the decay rate and whats giving enrichment during warm up.
Also the iac has to be open a large amount 75% of max to bring the idle up quick or it will stall cold. I would say the afterstart should be decayed to zero after about 2 minutes of run time and then let the coolant temperature maintain the rest of the enrichment until warm. Do not go into closed loop below 140f or surging will result and huge swings in corection and probalby stall.


Step 4 Go back and re-adjust afterstart decay rate (increase revs/per step until the decay is just right at the coolant temp your starting the engine at with the problem. The number or revs before afterstart table is exactly what it means number of crank revolutions before afterstart is applied, lower the number the sooner the afterstart is applied.


This is based on personal experience and others may have a different approach. Sorry for the long answer, but I;ve struggled alot with this and there is no easy way for a quick fix.

 

[RickWI]

Go into the system config screen then into operational parameters. I suspect your engine revs to run is 12 or so. Raise that up to 23 to 25. That should fix the starts then stalls deal. This will maintain cranking fuel for a slightly longer time prior to it going into normal run mode, which means mapped VE/pulsewidth, warm up enrichment then a nanosecond later, afterstart. The stall is usually at this transition.

If it cranks and cranks it needs more cranking pulsewidth enrichment versus coolant temp, as Norb was saying.

The stumble when cold is either too lean on warm up enrichment versus coolant temp and/or you need more AE fuel versus coolant temp.