Won't start after turning key off

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DEATH_INC.
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Won't start after turning key off

Post by DEATH_INC. » Sat Aug 08, 2015 1:34 pm

It's a 1600 NA with turbo and megasquirt.
A little history....I did the turbo and megasquirt conversion about 6 months ago, it ran fine for a while (maybe 1/2 doz decent drives) then was left sitting for a month or 2. Then it wouldn't start, so I started looking for the problem which I never really found, but for some reason looking up the ve map in the ecu made it start. Sent the ecu back to msnz, and he tried it in a couple of other mx5's which worked fine. As a precaution he sent Me back a ecu from another car which had been working fine also. Plugged it in and yes, it went. But no tacho and it won't go when you turn the key off and then try to restart it.
I've replaced the ignitor which has fixed the tacho, but it still won't re-start. It runs fine when it's running and seems to run as long as required.
Now, specifically it won't restart if you try it straight away after turning it off.
It restarts if you turn the key off then back on while the engine is still turning..
It restarts if you stall it and try without turning the key off (it won't if you do)
It restarts if you leave it for at least a minute.
I checked spark and injector pulse when it won't go and both seem to be ok. The ecu seems to be getting cranking signals etc.
It's got me stumped. Anyone got any ideas?

WideOpenThrottle
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Post by WideOpenThrottle » Sun Aug 09, 2015 9:26 am

I had something similar to yours a while back and it turned out to be the battery. I would also check the alternator as well even if they both turn out fine at least it eliminates them both from adding to the problem.
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DEATH_INC.
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Post by DEATH_INC. » Sun Aug 09, 2015 3:10 pm

Thanks, but not the battery/ alternator. It won't start even with a jump when it won't start, and the alternator is putting out plenty of charge.
It cranks over fine, just won't fire.

WideOpenThrottle
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Post by WideOpenThrottle » Sun Aug 09, 2015 8:44 pm

OK,so about fuel? Are you getting it at the injectors?
Have you tried other injectors?
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2low2c
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Post by 2low2c » Mon Aug 10, 2015 9:37 am

sounds like you might have a sticky master relay or efi relay

SLYDIT
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Post by SLYDIT » Mon Aug 10, 2015 8:46 pm

Get your injectors leak down tested
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Donovan
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Post by Donovan » Tue Aug 11, 2015 2:12 pm

Is the fuel pump working? I had the same thing, would crank over, turned out to be a relay to the fuel pump had fried itself.

DEATH_INC.
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Post by DEATH_INC. » Tue Aug 11, 2015 5:53 pm

Fuel pump runs fine ( Walbro, you can hear it pushing fuel through the reg, and actually hear it running) Injectors are new (from megasquirt), and fuel must be getting to the rail as you can hear it going through the reg.

If it was the master relay, would it cut power to the injectors? Or coil pack? Where is the best place to check this?
I'm guessing the efi reg would just kill the injectors?

I'll try to re-check these...the relay's kinda what I suspected too, but everything seems to have power...I must be missing something...

built4speed
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Post by built4speed » Wed Aug 12, 2015 7:09 am

If you have burnt out an igniter my guess is the dwell settings are wrong in the mega guess. The mitsi igniters are a fairly reliable from my experience. Poor grounds can accelerate their wear tho.
I've got a mx5 I'm stripping atm that has starting issues, I've tracked it down to the starter motor drawing too much voltage, a short or something inside I guess. A brand new battery will only show 8v with the car cranking.

Teamjelly
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Post by Teamjelly » Wed Aug 12, 2015 11:37 pm

If you don't get to the bottom of it
Or it gets too frustrating
Bring it down to Tauranga and leave it with me for a day or two
Can guarantee I'll get it up and running properly everytime- as I'm sure it's a simple fix.
Have plenty of coils.igniters,relays etc if that is the issue
Can give it a good dynotune at the same time if you like
Regards
Jared
Megasquirt NZ Ltd
Tga
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DEATH_INC.
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Post by DEATH_INC. » Thu Aug 13, 2015 6:18 pm

I'll check that cranking voltage...but it doesn't explain why it starts no probs after stalling....dwell should be ok as msnz set it up, and it's been running on another car too.
Thanks Jared (and for checking the MS out for me too) I'm a little way off giving up yet...and I do need that tune....I'll keep it in mind.

Teamjelly
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Post by Teamjelly » Thu Aug 13, 2015 6:28 pm

No worries
I'm' actually quite intrigued why it's happening, as it's a real oddball scenario
Let us know how you get on
:)
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DEATH_INC.
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Post by DEATH_INC. » Sat Aug 15, 2015 12:01 pm

Yeh...I am too, i can't for the life of me think what needs a 'rest' after you turn off the key...I will post up what I find...if I do.

Teamjelly
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Post by Teamjelly » Sat Aug 15, 2015 4:48 pm

It's got to be either fuel or spark
I'd put a 12v bulb (LEd with resistor works well)
In one of the injector plugs
And pull one of the leads
Then when it decides it doesn't want to start - you can see if the injectors are flashing and the coils are sparking
That will point you in the right direction

Of course it could be too much cranking enrichment when hot with the bigger injectors - So might need the crank table trimmed down a few milliseconds.
Since the B6 engine doesn't have a variable potentiometer TPS - you can't put the ECU into FLOOD CLEAR MODE
But what you could try is when it doesn't want to start - pull the fuel pump fuse and turn the engine over - if it's getting too much fuel then it will start and fire for a few seconds when the pump isn't going as the fuel pressure drains off
The old S4-5 RX7's had this exact hot start issue
Easily fixed with a few minor tune changes though
Sticking feathers up your butt does not make you a chicken

DEATH_INC.
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Post by DEATH_INC. » Sat Aug 22, 2015 10:54 am

Cool, will give that a shot...but i think it does it cold too...can't remember if I've tried it cold tho. Thanks.

DEATH_INC.
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Post by DEATH_INC. » Sun Sep 27, 2015 2:03 pm

Right...think I've found the problem, or at least it found itself...
WideOpenThrottle wrote:I had something similar to yours a while back and it turned out to be the battery. I would also check the alternator as well even if they both turn out fine at least it eliminates them both from adding to the problem.
This guy^ got it, though I still don't know why jumper leads didn't fix it and voltmeter didn't pick it up.
DEATH_INC. wrote:Thanks, but not the battery/ alternator. It won't start even with a jump when it won't start, and the alternator is putting out plenty of charge.
It cranks over fine, just won't fire.
This guy^ doesn't know what he's talking about. :oops:
Long story short, I did a coilover conversion on the billies and took it to work to align it, the battery was struggling to crank it after only 15 mins or so on the machine (brake light drain)....then it wouldn't start at all when I wanted to go home just wound over and wouldn't fire again.
:? so I figured f**k it and threw a new battery in, and it's started no problems ever since.

Thanks to all you guys that offered ideas. I'm gonna go hide in the corner for a while...

WideOpenThrottle
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Post by WideOpenThrottle » Mon Sep 28, 2015 9:03 am

Cool to see it fixed and decent enough to say what it turned out to be!
1989 NA 1650
1998 NB 1800
2005 NC 2000
1990 Landcruiser
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Push-bike
Hiking shoes

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Post by GRUVBB » Thu Oct 01, 2015 5:19 pm

WideOpenThrottle wrote:Cool to see it fixed and decent enough to say what it tyurned out to be!

yeah..good on ya. Takes a man to admit stuff like that to an open forum

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