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Fires but will not idle
Posted: Sun Jul 11, 2010 4:56 pm
by bigamil
So I've got a 489cc v8 with a blower on it. Running a EFI setup with high imp injectors. Originially put the whole motor together and threw some carbs on it to make sure everything was in time before I threw the blower and EFI system on.
The problem with the car now is that when I go to fire it it fires but then dies. I can smell fuel and believe its getting flooded.
Have my cranking pulse width set at 2% for all range of temps just so I can trouble shoot and try to get it to idle first.
Any idea on what the Cranking PW % should be set at? I looked through all the documentation and couldn't figure out what this needs to be set at.
Thanks guys!
Andrew
Re: Fires but will not idle
Posted: Sun Jul 11, 2010 11:54 pm
by trakkies
bigamil wrote:So I've got a 489cc v8 with a blower on it. Running a EFI setup with high imp injectors. Originially put the whole motor together and threw some carbs on it to make sure everything was in time before I threw the blower and EFI system on.
The problem with the car now is that when I go to fire it it fires but then dies. I can smell fuel and believe its getting flooded.
Have my cranking pulse width set at 2% for all range of temps just so I can trouble shoot and try to get it to idle first.
Any idea on what the Cranking PW % should be set at? I looked through all the documentation and couldn't figure out what this needs to be set at.
Thanks guys!
Andrew
If it is firing when cranking but then dies when you stop cranking, it means the cranking PW etc is near enough correct. You need to move on the the idle mixture. Assuming you are using the default tables or ones known to work with this engine, the normal way to do this is to alter the req fuel setting until you get a reliable idle, then put that back to the calculated value and transfer those changes to the VE table. Details in the MT manual.
Re: Fires but will not idle
Posted: Mon Jul 12, 2010 3:22 pm
by panel
Andrew.......try this.......it helped a lot with my start up.Quote from the manual.
If the engine starts and runs for a few seconds, then stalls, this is usually a sign that the afterstart enrichment isn't quite right. Leave everything else the same, and adjust the afterstart % and number of cycles. 20% to 30% and 200 cycles are reasonable starting points for most engines, but yours may run better with more or less. There should be a point at which it works without stalling.
If the engine starts and runs for more than 20 seconds or so, then stalls, you need to adjust your warm-up enrichment bins. As you adjust your warm-up bins, you may need to re-adjust the afterstart, since these interact (i.e., a larger warm-up value may require a shorter or smaller afterstart enrichment).
Re: Fires but will not idle
Posted: Fri Jul 16, 2010 6:47 am
by usagoal
Andrew,
Start with your required fuel. From Megatune, you should have been able to get a required fuel number. The manual suggests to use 88% of that required fuel number as your cold cranking pulse width and 23% as the warm cranking pulsewidth (given you are using the temperature values of -40 to 170 degrees). As the previous posts mentioned, you may have to mess with your afterstart enrichment if it dies right away. Will it idle if you hold the throttle open?
Re: Fires but will not idle
Posted: Mon Aug 02, 2010 3:44 pm
by spiyda
Andrew,
how long does it fire for before it dies.. ?
I have what sounds like an almost identical problem..
Ours fires but then dies after less than 1/2 second
supercharged 1300cc engine.. it was working on megasquirt Normally aspirated, but I can't get it going now it has a blower..
Chris
Re: Fires but will not idle
Posted: Sun Sep 26, 2010 4:28 pm
by Spittybug
I'm having a start problem too, so I'm learning from these posts.
A previous posted mentioned 88% of required fuel as the input for cranking PW%. So if I have a required fuel of 16.2, then my cranking PW% would be on the order of 14.25% ? Huh? Mine is set at 226% for coolant at 90 deg F. Is this my problem or am I misunderstanding the statement??
My ASE at 90 deg is set at 27% and my warmup enrichment at 113% for 80 deg coolant.
I have a GM idle stepper motor, start value 160, 2.6 step size, 5 sec crank to run taper.
I crank fine, run for a second or two and then die. Start right back up again, but can't get car to idle.
MSII, 2.85 liter, 6 cyl, odd fire.
Appreciate any help. Thanks.
Re: Fires but will not idle
Posted: Mon Sep 27, 2010 5:59 pm
by Spittybug
Well I've been able to get it running by increasing the % of both the after start and the warmup. It seems very sensitive. I'm still low on my fuel tables I believe since my 02 is showing high values. The auto generated table would appear to be quite lean I think. This will be a fairly long procedure to dial in I think....... I notice I idle at too low a value too. Going to have to fix that.