stalls after cold start
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- Master MS/Extra'er
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stalls after cold start
Wondering if someone can help me out here.. my car runs really well 99% of the time. However, on a true cold-start (first of the day), it starts, RPMs probably hit 1500-1700, starts to taper down, then dies. Re-starting (without power-cycling) and the engine will catch itself and then idle fine. Every now and then it will die after the 2nd restart, but usually it stays running. Log and MSQ included in the ZIP file.
Thanks in advance..
-Dave
Thanks in advance..
-Dave
'70 Chevelle ZZ383/700r4/3.73 MS3X, 36-1, LS Coils, Holley Stealthram -- success story
'92 Saturn 1.9 DOHC/5sp, MS3, Champcar racer success story
'79 Malibu DartSHP400/80mm/PG/3.55, MS3X/36-1/LS Coils -- success story
Porsche 944 S2 3.0 -- MS3X/36-1/LS Coils, 1:44s Mid-Ohio, Pro Course
'92 Saturn 1.9 DOHC/5sp, MS3, Champcar racer success story
'79 Malibu DartSHP400/80mm/PG/3.55, MS3X/36-1/LS Coils -- success story
Porsche 944 S2 3.0 -- MS3X/36-1/LS Coils, 1:44s Mid-Ohio, Pro Course
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- Super MS/Extra'er
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Re: stalls after cold start
That's a lot of timing at idle - you might want to try less timing and more throttle opening at idle. Running more than ~18 degrees at idle tends to make for idle stability issues.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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Re: stalls after cold start
Thanks Matt! That advice worked really well. Added +1 turn to throttle opening screw, it started and stayed running fine. Idle seemed a little too high, backed it off 1/2 turn, so net +1/2 added, dropped timing in idle area down to 18* and the combo of the two made a nice improvement in idle + off-idle.
-Dave
-Dave
'70 Chevelle ZZ383/700r4/3.73 MS3X, 36-1, LS Coils, Holley Stealthram -- success story
'92 Saturn 1.9 DOHC/5sp, MS3, Champcar racer success story
'79 Malibu DartSHP400/80mm/PG/3.55, MS3X/36-1/LS Coils -- success story
Porsche 944 S2 3.0 -- MS3X/36-1/LS Coils, 1:44s Mid-Ohio, Pro Course
'92 Saturn 1.9 DOHC/5sp, MS3, Champcar racer success story
'79 Malibu DartSHP400/80mm/PG/3.55, MS3X/36-1/LS Coils -- success story
Porsche 944 S2 3.0 -- MS3X/36-1/LS Coils, 1:44s Mid-Ohio, Pro Course
Re: stalls after cold start
I'm confused by this.Matt Cramer wrote:That's a lot of timing at idle - you might want to try less timing and more throttle opening at idle. Running more than ~18 degrees at idle tends to make for idle stability issues.
I'm running about 24 degrees at idle just to keep the car (Formula) stable.
On my C4, the stock PCM runs 36-37 degrees at idle, and that has a much smaller cam than the 412" on my Formula.
-- Joe
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Re: stalls after cold start
There used to be a meme going around that 5.0 Mustangs required 50 degrees of timing at idle, apparently based on some sort of stock map. And we had a LOT of Mustang owners complaining about unstable idle. When we released the MSPNP, which had a map that used far less idle timing, more people copied our map and these complaints about unstable idle dried up in a hurry.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Re: stalls after cold start
Stock map is about 28 deg. Yours is 16 deg.Matt Cramer wrote:There used to be a meme going around that 5.0 Mustangs required 50 degrees of timing at idle, apparently based on some sort of stock map. And we had a LOT of Mustang owners complaining about unstable idle. When we released the MSPNP, which had a map that used far less idle timing, more people copied our map and these complaints about unstable idle dried up in a hurry.
http://www.efidynotuning.com/saftot.htm
http://www.efidynotuning.com/mbt.htm
1988 Mustang GT, 59k miles, Orig Owner
ProCharger 600B I/C, 12psi, FRP Hdrs, Flwmstr F2, 3G Alt, Contour Fan & DCC, 3.55's, Prog Sprg, Subfms, UCA, LCA, FCA, Tokico 5's, Bridgestone RE-71R 245/40R17, Crane HI-6, Kirban FPR, MS2, DIYPNPF60, Spartan 2, C&L76mm blo-thru MAF, 47lb FRP-LU47
ProCharger 600B I/C, 12psi, FRP Hdrs, Flwmstr F2, 3G Alt, Contour Fan & DCC, 3.55's, Prog Sprg, Subfms, UCA, LCA, FCA, Tokico 5's, Bridgestone RE-71R 245/40R17, Crane HI-6, Kirban FPR, MS2, DIYPNPF60, Spartan 2, C&L76mm blo-thru MAF, 47lb FRP-LU47
Re: stalls after cold start
Any guidelines you use based on cam size ?Matt Cramer wrote:There used to be a meme going around that 5.0 Mustangs required 50 degrees of timing at idle, apparently based on some sort of stock map. And we had a LOT of Mustang owners complaining about unstable idle. When we released the MSPNP, which had a map that used far less idle timing, more people copied our map and these complaints about unstable idle dried up in a hurry.
I've been trying to dial in a tune on my 412" SBC and I have not had the best of luck. If I reduce the timing below 24-22 degrees I have to open the throttle blades quite a bit to maintain idle.
-- Joe
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Re: stalls after cold start
Greg Bannish put it best: Your goal for idle tuning is to balance engine torque against friction to hold the engine speed constant. An engine with a wild cam will need more help making enough torque to overcome friction, in the form of either air or timing. I've found more air is often a bit more stable than more timing.
Matt Cramer -1966 Dodge Dart slant six running on MS3X