unusual gremlin Electrical vs EFI glitch?

[bronco italiano]

The last two times I took the EB out I had the engine just die when coming to a stop sign (engine was not at operating temp yet. It also has done a brief "engine cutout" both times without engine die.
Each time I turned the key to off for 3-10 seconds and started right up
-I have the Ford SEFI (which has worked flawlessly for 12 years/11k miles).
-Ford AOD
-A9L ecm with diodes/caps replaced 5 years ago with chip tune
-Painless harness with at least 12 ground spots.
- Gotta be something simple. Other than this couple of hiccups, runs outstanding.

 

[73azbronco]

Voltage on battery engine off? On?

Fuel pressure?

 

[Oldtimer]

How old is ignition switch (electrical half)?

 

[ba123]

Could be your IAC valve or maybe you need to adjust your throttle stop screw.

IAC is cheap and does go bad sometimes but if you replace it, you do need to readjust the screw as well most likely.

Something to try.

 

[bronco italiano]

Voltage on battery engine off? On?

Fuel pressure?

I gotta check the pressure and my electrical wires to the pumps to make sure nothing is loose. Thanks

 

[bronco italiano]

How old is ignition switch (electrical half)?

From the painless kit, so 13 years old

 

[bronco italiano]

Could be your IAC valve or maybe you need to adjust your throttle stop screw.

IAC is cheap and does go bad sometimes but if you replace it, you do need to readjust the screw as well most likely.

Something to try.

That is one of the few non-ford parts in my truck and my idle does seem low for an auto (about 600 rpm at the stop light in gear since I started paying attention to it) since the glitch. Thanks

 

[SevenT]

That is one of the few non-ford parts in my truck and my idle does seem low for an auto (about 600 rpm at the stop light in gear since I started paying attention to it) since the glitch. Thanks

That is stick shift idle setting. You need to be closer to 800.

 

[bronco italiano]

And it used to be that high, so perhaps the IAC is acting up. Thanks

 

[ba123]

And it used to be that high, so perhaps the IAC is acting up. Thanks

Yup, without the IAC (or with it unplugged or faulty) it should still idle, but barely. With the IAC plugged in and working correctly, your idle should be where your ecu is programmed.

 

[ksagis]

And it used to be that high, so perhaps the IAC is acting up. Thanks

Does it run rough prior to dying? Pulled codes by chance?

My foxbody engine in Bronco does the something that sounds similar on very infrequent occasions. In my case, its pulling to stop, probably close to stopping, and flat out dies like it was turned off. Starts immediately.

For my symptoms and codes, I discounted IAC.

 

[DirtDonk]

Are you running a VSS? Sounds like something that would happen if the VSS was failing.
Or the wiring to the VSS was at fault.
And an A9L is a manual transmission computer. Presumably you’re running a “Ryan” harness? Or, if after Ryan, a Ron Francis? Or something else?
If either, I’m sure the jumpers are set to manual, or it would’ve fried something when you first fired it up 12 years ago.
But just curious about that.

 

[onpier55]

Mine did the same thing until I added in the Vss. Now it doesn’t stall when coming to an abrupt stop.

 

[ksagis]

Mine did the same thing until I added in the Vss. Now it doesn’t stall when coming to an abrupt stop.

Good thought. Were you getting code 29 prior to installing the VSS?

 

[onpier55]

No codes. It would just die when coming up stone stop sign and stopping fast. Haven’t had the problem since I added the Vss.

 

[bronco italiano]

Are you running a VSS? Sounds like something that would happen if the VSS was failing.
Or the wiring to the VSS was at fault.
And an A9L is a manual transmission computer. Presumably you’re running a “Ryan” harness? Or, if after Ryan, a Ron Francis? Or something else?
If either, I’m sure the jumpers are set to manual, or it would’ve fried something when you first fired it up 12 years ago.
But just curious about that.

DD, I do have a VSS (from WH actually). RJM harness. All has been perfect until recently. Besides the dying when I can to a stop I did have a couple engine stutter while driving steady. That was odd as one stutter happened before the engine dies coming to a stop and the second time it did a stutter shortly after it died coming to a stop. How do you check VSS?

 

[bronco italiano]

Does it run rough prior to dying? Pulled codes by chance?

My foxbody engine in Bronco does the something that sounds similar on very infrequent occasions. In my case, its pulling to stop, probably close to stopping, and flat out dies like it was turned off. Starts immediately.

For my symptoms and codes, I discounted IAC.

No rough running nefore it died, just decelerating for stop, but two very brief episodes of engine cutout but did not die

 

[DirtDonk]

Do you ever put gas additives in your tank? I do at least once a year, just to make sure I don’t get any water buildup inside.

Unfortunately, I don’t remember how to check a VSS. There’s probably a YouTube video on it, and with any luck, it only takes a volt/ohm meter. It would suck if you needed to put it on a oscilloscope, but sometimes that’s the case checking this kind of stuff.
Somebody here probably knows.

 

[bronco italiano]

DD, I only use Chevron 91 octane

 

[DirtDonk]

That's' good gas. But you can still get water in the tank now and then, so a little alcohol or additive to get the water to join with the gas and get burned is not a bad practice.
Do you need 91? Is the engine cammed and tuned? A stock one should run on 87 all day long and not complain.
I think the Chevron Techron that's in your 91 will keep things pretty clean. But does it work on water too? I forget. Guess I'll go read the label again next time I'm in a parts store!

And thinking more about the VSS, wasn't the A9L the one that benefitted the most from using one? So if you have one, maybe it's a good idear to test it.

Paul