New 383 won't idle on its own - misfires
11-14-2010, 03:26 PM
#1
New 383 won't idle on its own - misfires Finally got my 383 all put together. It's a low comp blower motor.
It won't stay idling on its own unless I give it gas even then it runs like a tractor - sounds like its running on about 4 cylinders. I started it and was reving between 2 and 3k then shut it off. I then went and made sure to check all the plug wires and that the firing order on the opti was right. It was and all the plug wires are on the spark plugs and opti tight. I did notice that some of the primaries were hot where others weren't.
I also double checked to make sure that the none of the injector wires were crossed and they were not.
Here is everything about the build I can think of:
Bottom end:
Displacement = 383
Compression = ~9.2ish to 1
Bore = 4.030
Stroke = 3.75
Crank = Lunati Sledgehammer
Rods = Lunati H beams
Pistons = Wiseco -20cc
Heads/Cam:
Valve Springs = K-motion (forgot exact spec, builder got them)
Rocker Arms = Comp Promag 1.6 NSA
Pushrods = Comp (forgot exact spec, builder got them)
Lifters = LS7
Cam = Comp Cams
Cam duration @ .50 = 218/230
Lift = .528 / .544
LSA = 114
Heads = Trick Flow 195cc
Head flow = 260/200 ish
Valve Diameter = 2.020 / 1.600
Combustion Chamber = 62cc
Timing Set = Cloyes Double Roller
Fueling:
Fuel Pump = Stock
Injectors = 72lb/hr RC racing
Regulator = Unknown adjustable aftermarket
Ignition:
Ignition Module = MSD 6A
Coil = MSD
Distributor = Stock with MSD cap & rotor
Wires = MSD 8.5mm OTVC
Plugs = Autolite 3924s
Tune = Madz28.com
It won't stay idling on its own unless I give it gas even then it runs like a tractor - sounds like its running on about 4 cylinders. I started it and was reving between 2 and 3k then shut it off. I then went and made sure to check all the plug wires and that the firing order on the opti was right. It was and all the plug wires are on the spark plugs and opti tight. I did notice that some of the primaries were hot where others weren't.
I also double checked to make sure that the none of the injector wires were crossed and they were not.
Here is everything about the build I can think of:
Bottom end:
Displacement = 383
Compression = ~9.2ish to 1
Bore = 4.030
Stroke = 3.75
Crank = Lunati Sledgehammer
Rods = Lunati H beams
Pistons = Wiseco -20cc
Heads/Cam:
Valve Springs = K-motion (forgot exact spec, builder got them)
Rocker Arms = Comp Promag 1.6 NSA
Pushrods = Comp (forgot exact spec, builder got them)
Lifters = LS7
Cam = Comp Cams
Cam duration @ .50 = 218/230
Lift = .528 / .544
LSA = 114
Heads = Trick Flow 195cc
Head flow = 260/200 ish
Valve Diameter = 2.020 / 1.600
Combustion Chamber = 62cc
Timing Set = Cloyes Double Roller
Fueling:
Fuel Pump = Stock
Injectors = 72lb/hr RC racing
Regulator = Unknown adjustable aftermarket
Ignition:
Ignition Module = MSD 6A
Coil = MSD
Distributor = Stock with MSD cap & rotor
Wires = MSD 8.5mm OTVC
Plugs = Autolite 3924s
Tune = Madz28.com
11-14-2010, 03:48 PM
#3
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Fuel Pump = Stock
Injectors = 72lb/hr RC racing
Are you crazy guy...... you are running 72lb injectors with a stock fuel system... you should be running dual walbo pumps.... If i was you i would not start it.
Injectors = 72lb/hr RC racing
Are you crazy guy...... you are running 72lb injectors with a stock fuel system... you should be running dual walbo pumps.... If i was you i would not start it.
11-16-2010, 02:11 PM
#6
I pulled the driver's side plugs.
1 and 7 look black after 1 min of total run time. 3 and 5 look normal. Going to try turning it over by hand and see if any gas comes out. Then on to the pass plugs I guess.
I should add that Ion (madz28.com) was the tuner.
Pulled plugs on the pass side. 6 and 8 are black too. 2 and 4 are normal.
I turned the engine by hand now, no gas came out.
1 and 7 look black after 1 min of total run time. 3 and 5 look normal. Going to try turning it over by hand and see if any gas comes out. Then on to the pass plugs I guess.
I should add that Ion (madz28.com) was the tuner.
Pulled plugs on the pass side. 6 and 8 are black too. 2 and 4 are normal.
I turned the engine by hand now, no gas came out.
Last edited by Z28Roxy; 11-16-2010 at 02:50 PM.
11-16-2010, 02:49 PM
#7
ok first off even on a stock pump the motor will idle and part throttle fine.........beyond that if you use a screwdriver to your ear can you hear all the injectors clicking open/closed? how about plug wires are they all pushed on the plugs and cap well and nothing is burnt? as for the tune he shouldn't have touched the cylinder balance so i dont think the tune is your issue.......also how bout adjusting the valves how did you do it?
worst case scenario maybe the dist cap/rotor isn't working to well......
worst case scenario maybe the dist cap/rotor isn't working to well......
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11-16-2010, 02:56 PM
#8
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if the idle is that bad and plugs are off then you have a fuel/air problem... leading me to your tps and ICM count.. check and see if your TPS is between .60v-.70v and ICM at hot idle is no less then 30 and no higher then 60... if so you have some adjusting to do... hope that helps
11-16-2010, 03:06 PM
#9
ok first off even on a stock pump the motor will idle and part throttle fine.........beyond that if you use a screwdriver to your ear can you hear all the injectors clicking open/closed? how about plug wires are they all pushed on the plugs and cap well and nothing is burnt? as for the tune he shouldn't have touched the cylinder balance so i dont think the tune is your issue.......also how bout adjusting the valves how did you do it?
worst case scenario maybe the dist cap/rotor isn't working to well......
worst case scenario maybe the dist cap/rotor isn't working to well......
I didn't do any of the engine work, my builder did that. Also my distrib cap and rotor is basically new....
11-16-2010, 03:07 PM
#10
if the idle is that bad and plugs are off then you have a fuel/air problem... leading me to your tps and ICM count.. check and see if your TPS is between .60v-.70v and ICM at hot idle is no less then 30 and no higher then 60... if so you have some adjusting to do... hope that helps
11-16-2010, 04:51 PM
#12
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Did you datalog it yet that would kill al of this guess work we are doing???
if so add your TPS volts and IAC counts
11-17-2010, 08:08 AM
#13
11-20-2010, 04:19 PM
#14
Update: Have not datalogged yet. I did try swapping PCMs since that's easy. I did try hooking up a timing light and cranking it with the injector fuses pulled and it would flash normal but there would be an EXTRA blink in there every so often on all cylinders.
11-20-2010, 05:18 PM
#15
I know this is elementary but you did verify the order on the cap and did not assume it was front to back top to bottom right. I mean you actually looked at the numbers on the cap?
Sounds to me like a pair is swapped on each side. If the plugs got black that fast I would bet the initial tune is setup REALLY rich. Harder to hurt a motor with too rich so he might have aimed rich on the initial tune. Guessing 72s are tough to get to idle anyway.
injector order has to do with stock idle emissions and a SLIGHT bit of smoother idle, you could mix them all up and it should run fine. Remember a LOT of cars were built batch fire not sequential.
I agree for what you are doing the stock pump is fine.
Did you verify the fuel pressure? The aftermarket regulator could be cranked up too high causing the overrich on the 4 cylinders firing
Sounds to me like a pair is swapped on each side. If the plugs got black that fast I would bet the initial tune is setup REALLY rich. Harder to hurt a motor with too rich so he might have aimed rich on the initial tune. Guessing 72s are tough to get to idle anyway.
injector order has to do with stock idle emissions and a SLIGHT bit of smoother idle, you could mix them all up and it should run fine. Remember a LOT of cars were built batch fire not sequential.
I agree for what you are doing the stock pump is fine.
Did you verify the fuel pressure? The aftermarket regulator could be cranked up too high causing the overrich on the 4 cylinders firing
11-21-2010, 03:09 PM
#18
Tried a new coil. Same thing would happen with the timing light:
Flash........................FlashFlash........... ...Flash.......................FlashFlash
Hooked up the FP tester. 42psi.
I got a datalog now, but I need to host it somewhere. It still ran like ****.
Flash........................FlashFlash........... ...Flash.......................FlashFlash
Hooked up the FP tester. 42psi.
I got a datalog now, but I need to host it somewhere. It still ran like ****.
11-21-2010, 04:35 PM
#20
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i just seen your file and your first problem is your tps is .08v and your iac count is at 128 ( i posted early you needed to check these two things while will cause the car to run rough) you need your tps at or between .55 to .65 find a sweet spot and IAC should be around 30-45 go try that and put up another log