POP when turning ignition on (not cranking) and burned fuel smell - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 11-26-2008, 09:00 PM   #61
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Has any one solved this problem yet?
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Old 11-26-2008, 09:36 PM   #62
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Originally Posted by Joe Perez View Post
No, it seems to be only a small subset of MS1 users, and I expect probably some MS2 users as well.
I've got EDIS4, so I don't deal with this problem. But even MS2E when I controlled the factory coil this was never a problem. And never heard of anyone MS2 ever having this happen before.

I don't think injectors have anything to do with it. To me, this is clearly a function of MS1 firing the spark plugs. A leaky injector isn't gonna lite the mixture.
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Old 11-26-2008, 11:31 PM   #63
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Originally Posted by patsmx5 View Post
To me, this is clearly a function of MS1 firing the spark plugs. A leaky injector isn't gonna lite the mixture.
No question- the combustion event is caused by the fact that the plugs fire at powerup, which is a function of the output circuit design, not the CPU. The question is- where is the fuel coming from in the first place, and why do so many of us not have the issue? IOW: What's the variable? It certainly isn't the software or the circuit.
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Old 11-27-2008, 01:03 AM   #64
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Originally Posted by wes65 View Post
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.
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Originally Posted by Spookyfish View Post
@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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Originally Posted by paul View Post
I run a stock flywheel and i get the pop 2 secs after i turn the key.

Joe, these three people report that changing the injector fire time for the priming pulse "moves" the time when the pop happens. So that kinda rules out the plugs sparking at power up being the cause.

To me, it's obvious what's happening. What I can't tell you is why it's happening. Whenever MS decides to fire the injectors, it's triggering the coils. Probably triggering all of them such that the cylinder with an open intake valve is always fired. A timing light would verify this. Someone should kill the fuel pump to their car, put a timing light on a spark plug wire, set the priming pulse for say, 1 sec, and see if it fires the plug after 1 sec. Then change to two seconds and see if it now fires at 2 seconds. See if there's a correlation. I bet there is. It's obviously firing the plugs whenever it's priming. Of course it shouldn't, but it is.

More prone to happen at cold start? You spray more fuel for the priming pulse at cold start. See a correlation?

I don't think this has anything to do with leaky injectors. To me, it looks like MS is firing the plugs whenever it fires the injectors for the priming pulse. I hope somebody puts a timing light to it to see if what I speculate above is correct.

But alas I have this shitty EDIS that's overly complex and has no real benefits over letting MS control the ignition coils directly. But it works flawlessly.

Last edited by patsmx5; 11-27-2008 at 01:21 AM.
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Old 12-01-2008, 08:09 PM   #65
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Quote:
Originally Posted by patsmx5 View Post
Joe, these three people report that changing the injector fire time for the priming pulse "moves" the time when the pop happens. So that kinda rules out the plugs sparking at power up being the cause.
I'm pretty sure Sookyfish said the priming pulse did not affect the timing of the pop when he said:

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Originally Posted by Spookyfish View Post
Tried the 'After two seconds', but that doesnt change the behaviour. Only takes longer to crank the car.
I've noticed the same thing. My car pops the moment the ignition is switched on, regardless of settings.

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Originally Posted by patsmx5 View Post
To me, it's obvious what's happening. What I can't tell you is why it's happening. Whenever MS decides to fire the injectors, it's triggering the coils. Probably triggering all of them such that the cylinder with an open intake valve is always fired. A timing light would verify this. Someone should kill the fuel pump to their car, put a timing light on a spark plug wire, set the priming pulse for say, 1 sec, and see if it fires the plug after 1 sec. Then change to two seconds and see if it now fires at 2 seconds. See if there's a correlation. I bet there is. It's obviously firing the plugs whenever it's priming. Of course it shouldn't, but it is.
I just did this. Timing light confirmed that there is a single ignition event right after I switch the key to run. Changing the priming pulse did nothing. No matter the settings, there is a single spark event once the MS gets power (or a fraction of a second thereafter). We knew this though. Also, there isn't another ignition event until cranking begins.

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Originally Posted by patsmx5 View Post
More prone to happen at cold start? You spray more fuel for the priming pulse at cold start. See a correlation?
My priming pulse won't ignite even if I try. If I switch on the ignition, wait for the pulse, then switch off and back on again, it won't pop. It only pops after at least 48 hrs of non-operation.

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Originally Posted by patsmx5 View Post
I don't think this has anything to do with leaky injectors. To me, it looks like MS is firing the plugs whenever it fires the injectors for the priming pulse. I hope somebody puts a timing light to it to see if what I speculate above is correct.
I think this is a direct result of leaking injectors. The MS is firing my plugs every time it gets switched on. The priming pulse and the ignition event are independent in my setup.
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Old 12-01-2008, 08:22 PM   #66
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Well, Wes65 said:

Quote:
Originally Posted by wes65 View Post
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.
And then immediately proceeding this post, Spookyfish said:

Quote:
Originally Posted by Spookyfish View Post
@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.
Hence why I said he seems to have the same problem.

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Originally Posted by chucker View Post
I'm pretty sure Sookyfish said the priming pulse did not affect the timing of the pop when he said:



I've noticed the same thing. My car pops the moment the ignition is switched on, regardless of settings.



I just did this. Timing light confirmed that there is a single ignition event right after I switch the key to run. Changing the priming pulse did nothing. No matter the settings, there is a single spark event once the MS gets power (or a fraction of a second thereafter). We knew this though. Also, there isn't another ignition event until cranking begins.



My priming pulse won't ignite even if I try. If I switch on the ignition, wait for the pulse, then switch off and back on again, it won't pop. It only pops after at least 48 hrs of non-operation.



I think this is a direct result of leaking injectors. The MS is firing my plugs every time it gets switched on. The priming pulse and the ignition event are independent in my setup.
And I read your other talk about "testing" the fuel injectors for leaks. I can tell you if the car sits long enough, the pressure WILL go down. But of course it would be leaking back through the pump. Pretty sure this is normal. Hence why when you turn the key on, the pump primes for a couple seconds. Not really sure how to tell you to test for leaky fuel injectors.

I still find it "strange" that MS2 cars don't exhibit this problem but several MS1 cars do. And a few MS1 cars say that changing the priming pulse does move this pop around. I still think this is a function/problem with MS1, not leaky fuel injectors.

And finally, I think some of the people that say moving the priming pulse around moves the pop around should do the timing light thing to verify if MS is sparking when firing that priming pulse.

Had two different sets of injectors in my 99' with and w/o MS and never had this problem.

I'll close with a question: Does ANYONE who is not MS1 have "the pop"?
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Old 12-01-2008, 08:48 PM   #67
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And I read your other talk about "testing" the fuel injectors for leaks. I can tell you if the car sits long enough, the pressure WILL go down. But of course it would be leaking back through the pump.
Yeah, I agree with you here.

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Originally Posted by patsmx5 View Post
I still find it "strange" that MS2 cars don't exhibit this problem but several MS1 cars do. And a few MS1 cars say that changing the priming pulse does move this pop around. I still think this is a function/problem with MS1, not leaky fuel injectors.
Maybe it's simply a function of the smaller population of MS2 cars? IOW, maybe the problem affects them as well but we just haven't heard about it..

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And finally, I think some of the people that say moving the priming pulse around moves the pop around should do the timing light thing to verify if MS is sparking when firing that priming pulse.
Great idea.

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Originally Posted by patsmx5 View Post
I'll close with a question: Does ANYONE who is not MS1 have "the pop"?
Great question.
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Old 12-01-2008, 09:11 PM   #68
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I have prime pulse always, then fire after 2 seconds....never hear the pop...only when I slightly flood the motor when I'm fooling around with stuff.

if you turn it the ignition to ON, then off....it will pop right? will it happen if you do that say two three times in a row?

if no, then turn the car to ON and let your fuel pump run for 5 minutes, then try it...does it happen then?
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Old 12-01-2008, 09:21 PM   #69
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if you turn it the ignition to ON, then off....it will pop right? will it happen if you do that say two three times in a row?
if no, then turn the car to ON and let your fuel pump run for 5 minutes, then try it...does it happen then?
If I switch to on, then off, it will not pop. I just tried it three times in a row and still no pop. Seems the only time this will happen is if the car has been sitting for a couple days.
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Old 12-01-2008, 09:21 PM   #70
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so you have a leaky injector


let the fuel pump run for a while, while the ignition is just set to ON. wait like 10-15 minutes, then test for the pop.
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Old 12-01-2008, 09:23 PM   #71
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so you have a leaky injector
******' A.
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Old 12-01-2008, 09:31 PM   #72
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So if the fuel injector leaks (fuel into the intake manifold) after sitting a few days it will pop.

But if you turn the key on after warm start and they injector sprays (fuel into the intake manifold) it won't pop.

And therefore it's a leaky injector? I don't buy it. Why would one fuel/air/spark combination ignite and another not?
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Old 12-01-2008, 09:35 PM   #73
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Originally Posted by patsmx5 View Post
Why would one fuel/air/spark combination ignite and another not?
Just a long-shot guess - after sitting overnight, with a gradual drip drip, there's more vaporization happening (less liquid fuel)? Making it easier to set off?
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Old 12-01-2008, 11:23 PM   #74
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Originally Posted by patsmx5 View Post
Joe, these three people report that changing the injector fire time for the priming pulse "moves" the time when the pop happens. So that kinda rules out the plugs sparking at power up being the cause.
I just don't see it. I put an MS1 configured for a Miata on the bench and scoped the injector and igniter outputs during several power-ons. In each case, the spark output went high immediately at power on, then went low as soon as the CPU programmed and came to life. When fuel prime was set to "Power on", the injector output went active at the same instant that the igniter output went low. IOW, the spark event happened at pretty much the exact millisecond that the injector started priming. No further spark events occurred. Fuel does not travel at the speed of light, and that's what would have to happen in order for it to get from the injector, down the port, past an open intake valve and into the chamber in time to hit the spark plug while the arc was still drawn.


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So if the fuel injector leaks (fuel into the intake manifold) after sitting a few days it will pop.

But if you turn the key on after warm start and they injector sprays (fuel into the intake manifold) it won't pop.

And therefore it's a leaky injector? I don't buy it. Why would one fuel/air/spark combination ignite and another not?
Because with a leaky injector, there is plenty of time (measured in hours) for fuel to vaporize and migrate down the relatively long intake port into the combustion chamber.

When the injectors prime, however, there just isn't enough time for the fuel droplets to find their way into the chamber, much less vaporize.
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Old 12-02-2008, 03:48 AM   #75
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I will clarify myself:
Quote:
@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.
This means just what I say.

However:
Quote:
Tried the 'After two seconds', but that doesnt change the behaviour. Only takes longer to crank the car.
This means the problem is still there (either at 0s or 2s) and it does not solve the problem.
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Old 12-02-2008, 03:53 AM   #76
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Joe: interesting results. Did you also monitor power-off cycles? I wont if it is a leaky injector or that power-off results in injectors opening for a short time...
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Old 12-04-2008, 12:18 PM   #77
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Joe: interesting results. Did you also monitor power-off cycles?
I didn't but I will if I get a chance here soon. I don't think that the injectors are going to specifically fire at power-off, as I'd expect that the +12v to drive them (on the white/red wire) will fall to zero much faster than the MS's internal Vcc, which has some reserve capacity in the form of the large electrolytic caps in the supply.

What I'm sure does probably happen from time to time is that at the instant you turn off the key, two of the injectors are squirting normally, however after you turn off the key, the associated spark event never happens, thus leaving fuel lying around. On a normal engine, I assume that said fuel winds up being cleared through the chambers owing to the fact that the engine continues turning (as a function of the momentum of the flywheel) for a short while after the key is switched off. I guess some day I should measure the amount it typically turns after power off- should be easy by scoping my VR sensor relative to +12.
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Old 12-04-2008, 01:03 PM   #78
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What if the ignition outputs are momentarily interrupted with a normally closed double pole pushbutton?

For cold starts, the sequence would be: depress interrupt switch, turn on ignition, start cranking, immediately release switch.

Please tell me if this is super retarded.

It would take a bit of time to install and it’d be a bit of a nuisance at startup but it’d only be for cold starts, it’d only cost a few bucks, and it’d be easier/cheaper than sourcing new injectors…
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Old 12-04-2008, 01:19 PM   #79
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What if the ignition outputs are momentarily interrupted with a normally closed double pole pushbutton?

For cold starts, the sequence would be: depress interrupt switch, turn on ignition, start cranking, immediately release switch.

Please tell me if this is super retarded.

It would take a bit of time to install and it’d be a bit of a nuisance at startup but it’d only be for cold starts, it’d only cost a few bucks, and it’d be easier/cheaper than sourcing new injectors…

:wtf:
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Old 12-04-2008, 01:21 PM   #80
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better idea, why don't you just heat the car up before starting it.
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