Engine randomly leans out and dies for no apparent reason

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turbo-brooks
MegaSquirt Newbie
Posts: 20
Joined: Tue Jan 11, 2011 7:08 pm

Engine randomly leans out and dies for no apparent reason

Post by turbo-brooks »

I've FINALLY got this thing running, but not driving it just yet - but just idling for no certain amount of time, or no apparent temperature threshold - it leans out and dies.

I've adjusted ASE/WUE, squirts per cycle, just about everything fuel related I can find and the problem still persists. There doesn't seem to be any signifigant voltage spikes. All of my connections are soldered. Grounds are by the book - The wideband is grounded to the same place as the MS is. I'm sure it's something simple, but I'm just not seeing it.

It's tuned with TunerStudio, V3 Mainboard. Latest firmware- version escapes me right now.

It's a Chevy 383 using direct coil control, VR sensor (inside the distributor), 80# injectors etc.
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Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Engine randomly leans out and dies for no apparent reaso

Post by Matt Cramer »

Looks like a WUE issue, as the engine leaned out about the same time as an abrupt rise in temperature. It suddenly jumped from around 95 to 165 degrees in the space of about a minute. Where's your coolant temperature sensor located? I get the feeling it's measuring things wrong.

On an unrelated issue... 38 degrees timing advance at idle doesn't seem like a good idea to me.
turbo-brooks
MegaSquirt Newbie
Posts: 20
Joined: Tue Jan 11, 2011 7:08 pm

Re: Engine randomly leans out and dies for no apparent reaso

Post by turbo-brooks »

It's a turbo car, and the high advance (down low) helps it spool up fast - it's not WOT tuned yet, so - obviously the lead will be pulled WAY back under boost.

The abrupt rise in temperature came from a partially filled radiator, but I figured out the real problem yesterday.

There were two problems.

One - the pot's had not been properly adjusted and it was dropping tach counts pretty regularly (can be seen in that log). The dying part, was directly related to this. Once it was adjusted with the oscilliscope, it never died again, even though it was seriously lean. (but it did misfire)

Two - the injector opening time was only set at 1.0Ms, these are fairly big injectors and they just don't snap open and closed that quick.... I upped the opening time to either 1.2 or 1.4 (can't remember- alternator is kinda weak I think). The lean spots after warmup were GONE. Now, I have to go back and retune the WUE and ASE with the increased injector opening time.
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