POP when turning ignition on (not cranking) and burned fuel smell
10-02-2008, 07:23 PM
#42
Boost Pope
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Because you're deliberately spinning up the turbo just before killing the oil supply. The engine will wind down almost immediately, whereas the turbo will keep going for a while.
I just don't have the problem on my car. If I've turned the key to run, waited for prime, and then switched off, waited some more, and then back on, then yeah, I'll occasionally get the pop.
I just don't have the problem on my car. If I've turned the key to run, waited for prime, and then switched off, waited some more, and then back on, then yeah, I'll occasionally get the pop.
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10-02-2008, 08:05 PM
#43
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Because you're deliberately spinning up the turbo just before killing the oil supply. The engine will wind down almost immediately, whereas the turbo will keep going for a while.
I just don't have the problem on my car. If I've turned the key to run, waited for prime, and then switched off, waited some more, and then back on, then yeah, I'll occasionally get the pop.
I just don't have the problem on my car. If I've turned the key to run, waited for prime, and then switched off, waited some more, and then back on, then yeah, I'll occasionally get the pop.
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10-02-2008, 08:16 PM
#44
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I doubt it. Again, this initial spark event takes place before the MS really has a chance to do much else in terms of priming events. If you look at the source code, you'll see that the relevant output pins get initialized way before the real meat of the main loop starts happening.
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10-03-2008, 02:29 AM
#46
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@wes65: I was observing the samen 0s or 2s delay. Maybe I should grab a timing light, turn the ignition on and see how many pulses I get and when... maybe that will tell me something.
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10-03-2008, 08:39 AM
#47
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For those with TPS, you could try to use the flood clear at night while cranking...should expel/burn any excess gas....
TPS VALUE FOR FLOOD CLEAR
Sometimes you might want to temporarily stop the injectors from injecting fuel during cranking to clear a flooded engine. This is achieved by holding down the gas pedal during cranking. The MegaSquirt needs to know at what point of gas pedal deflection it should turn off the injectors and a good starting point would be just before floored.
Insert this value for the TPS Flood Clear.
TPS VALUE FOR FLOOD CLEAR
Sometimes you might want to temporarily stop the injectors from injecting fuel during cranking to clear a flooded engine. This is achieved by holding down the gas pedal during cranking. The MegaSquirt needs to know at what point of gas pedal deflection it should turn off the injectors and a good starting point would be just before floored.
Insert this value for the TPS Flood Clear.
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10-25-2008, 09:07 AM
#48
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I have the "turn the ignition on = BANG ! "
.I had my MS p&p fitted and tunned by a well trusted tunner as i just don't have the know how/skill etc.He has tried a few fixes but has come up blank.So i am following this thread with interest 
Car:97 1.8 na
FI = BRP MP62 SC
Injectors: 320 cc
.I had my MS p&p fitted and tunned by a well trusted tunner as i just don't have the know how/skill etc.He has tried a few fixes but has come up blank.So i am following this thread with interest Car:97 1.8 na
FI = BRP MP62 SC
Injectors: 320 cc
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10-25-2008, 10:36 AM
#50
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Another thought: while the MSPNP has all outputs high while booting, is this also the case while shutting down? Maybe the inj are pulsed during shutdown and depending on time and temperature there is enough combustable fuel in one or more cylinders that will burn during the next bootup (spark output high). Idea?
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10-25-2008, 11:12 AM
#51
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Even if this were not the case, though, I'm having trouble visualizing whether it would be possible for the fuel to hang around. The engine does not stop spinning the instant that you turn off they key. The internals have momentum, and the crank will continue to rotate for a little while (drawing air in, compressing it, expanding it, and exhausting it) as it slows down to a stop. I just have no idea how long the engine continues to rotate for. Would it complete a full cycle (two revolutions) thus clearing the intake tract and cylinders of residual fuel? I have no idea.
Here's a wild question: Those of you experiencing this problem, are you running lightened flywheels?
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10-25-2008, 01:19 PM
#54
The one thing that bothers me is the fact that my pop always happens 2 seconds after the key is turned on. I can change this by changing the "Fire priming pulse" option. If i change it to on power on, it happens almost instantly at key on. If it is set to after 2 seconds, it happens after 2 seconds.
I don't see how it would be possible on the injector channels. Unlike the ignition drivers, their natural tendency is to be off, and the CPU must pull the drive lines high to turn them on.
Even if this were not the case, though, I'm having trouble visualizing whether it would be possible for the fuel to hang around. The engine does not stop spinning the instant that you turn off they key. The internals have momentum, and the crank will continue to rotate for a little while (drawing air in, compressing it, expanding it, and exhausting it) as it slows down to a stop. I just have no idea how long the engine continues to rotate for. Would it complete a full cycle (two revolutions) thus clearing the intake tract and cylinders of residual fuel? I have no idea.
Here's a wild question: Those of you experiencing this problem, are you running lightened flywheels?
Even if this were not the case, though, I'm having trouble visualizing whether it would be possible for the fuel to hang around. The engine does not stop spinning the instant that you turn off they key. The internals have momentum, and the crank will continue to rotate for a little while (drawing air in, compressing it, expanding it, and exhausting it) as it slows down to a stop. I just have no idea how long the engine continues to rotate for. Would it complete a full cycle (two revolutions) thus clearing the intake tract and cylinders of residual fuel? I have no idea.
Here's a wild question: Those of you experiencing this problem, are you running lightened flywheels?
I definitely think a timing light on every cylinder is in order. See if they're all sparking on their own randomly or what. But GL finding 4 timing lights.
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10-25-2008, 07:24 PM
#56
I have never had this problem with MS2. I could turn the key on and off 10 times and then yeah it would be flooded and hard to start but never pops. Same with EDIS now I can flood it if I prime it enough but never does it pop.
Does everyone MS 1 deal with this and not talk about it?
Does everyone MS 1 deal with this and not talk about it?
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10-25-2008, 09:33 PM
#58
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No, it seems to be only a small subset of MS1 users, and I expect probably some MS2 users as well. I do not experiance this issue and never have, nor have many others that I've spoken to.
My strongest suspicion is that this is caused by injectors leaking tiny amounts of fuel into the intake runners after shutdown.
I'm also chewing on the very remote possibility that engines with light flywheels might not complete a full cycle of rotation after shutdown, thus leaving some fuel that has been injected but not ignited in the engine. Perhaps we can gather some empirical data on this topic.
Whatever the cause, I am nearly 100% certain that it is not due to fuel being injected at or immediately following turn-on. With no airflow through the engine, it does not seem plausible that fuel could travel from the injector all the way down the intake port and into the cylinder, while remaining sufficiently atomized to be easily ignitable, in the relatively brief period of time
I've got a MS sitting on my desk nearly completed at the moment, and I'm hoping to scope its squirt and spark output lines before I have to give it back to the owner, to establish an accurate timeline of what actually happens at power-up.
My strongest suspicion is that this is caused by injectors leaking tiny amounts of fuel into the intake runners after shutdown.
I'm also chewing on the very remote possibility that engines with light flywheels might not complete a full cycle of rotation after shutdown, thus leaving some fuel that has been injected but not ignited in the engine. Perhaps we can gather some empirical data on this topic.
Whatever the cause, I am nearly 100% certain that it is not due to fuel being injected at or immediately following turn-on. With no airflow through the engine, it does not seem plausible that fuel could travel from the injector all the way down the intake port and into the cylinder, while remaining sufficiently atomized to be easily ignitable, in the relatively brief period of time
I've got a MS sitting on my desk nearly completed at the moment, and I'm hoping to scope its squirt and spark output lines before I have to give it back to the owner, to establish an accurate timeline of what actually happens at power-up.
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10-26-2008, 12:35 AM
#59
Count me in as a user who experiences this Phenomenon. I've got a 7lb flywheel and MS1. It ignites as soon as the key is turned to the ON position. I hate when I have to go searching for a vacuum cap that was just propelled from my intake manifold with explosive force.
Last edited by Bryce; 10-26-2008 at 01:45 AM.
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10-26-2008, 02:29 AM
#60
My flywheel is 17# (OE NB)
I get the pop with great reliability.
More time between cold-starts means a greater pop.
2 pair of professionally cleaned injectors have behaved nearly identically in 2 different engines; all configurations have popped at every cold-start; MS has been the only commonality.
Seemingly all MT settings have been tested.
The condition remains.
I get the pop with great reliability.
More time between cold-starts means a greater pop.
2 pair of professionally cleaned injectors have behaved nearly identically in 2 different engines; all configurations have popped at every cold-start; MS has been the only commonality.
Seemingly all MT settings have been tested.
The condition remains.
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