unusual gremlin Electrical vs EFI glitch?

[ksagis]

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

Wanted to double check to make sure I understand, are you saying that you did check codes, and even through you didn’t have VSS, it wasn’t throwing any codes?

Or are you saying you didn’t check codes?

If the first one, that’s interesting to me for sure as I would assume the ECU would flag a missing VSS.

 

[ba123]

I might be crazy in my opinion, but despite codes, I am pretty confident that there is no chance that the lack of VSS signal is going to make the engine die.

No chance.

 

[lars]

I might be crazy in my opinion, but despite codes, I am pretty confident that there is no chance that the lack of VSS signal is going to make the engine die.

No chance.

Not so. My very manual transmission engine controlled by a then-stock A9L would reliably die pulling up to a stop, despite messing with idle stop etc. Added the VSS, problem went away. It was a known issue in the Mustang world (corral.net, this was 20-something years ago). Of course that was before I started tuning with a Tweecer, possibly could've dialed that out but by then the VSS was in and working.

In this case I'm thinking more like IAC valve and/or fuel pressure. I *really* like my fuel pressure gauge. Great diagnostic tool.

 

[ba123]

Not so. My very manual transmission engine controlled by a then-stock A9L would reliably die pulling up to a stop, despite messing with idle stop etc. Added the VSS, problem went away. It was a known issue in the Mustang world (corral.net, this was 20-something years ago). Of course that was before I started tuning with a Tweecer, possibly could've dialed that out but by then the VSS was in and working.

In this case I'm thinking more like IAC valve and/or fuel pressure. I *really* like my fuel pressure gauge. Great diagnostic tool.

IAC was my guess.

When I first put in my Mustang 5.0 in ‘98 and drove it for a year, I didn’t have VSS hooked up and ran great. I did have an A9P, not sure how much diff that makes, but I had no issues.

That’s crazy if it really does.

 

[lars]

IAC was my guess.

When I first put in my Mustang 5.0 in ‘98 and drove it for a year, I didn’t have VSS hooked up and ran great. I did have an A9P, not sure how much diff that makes, but I had no issues.

That’s crazy if it really does.

A9L was notorious for the stalling. The P, not so much. And because all the cool kids had A9Ls, I had to have that one myself. Natch. It's now resting comfortably on my office desk, having been replaced by a reflashed Explorer PCC1 that does things it could't, and without external hardware.

 

[bronco italiano]

Wanted to double check to make sure I understand, are you saying that you did check codes, and even through you didn’t have VSS, it wasn’t throwing any codes?

Or are you saying you didn’t check codes?

If the first one, that’s interesting to me for sure as I would assume the ECU would flag a missing VSS.

I have VSS and ecm with moates quarterhorse tune (dyno tuned too)/chip burned years ago by a CB member. The eb has run flawlessly for 12 years/11k miles. I am going to check for a code but by check engine light isn't on.

 

[bronco italiano]

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

DD, engine is cammed/tuned 10:1 CR. I am gonna do some tests this weekend. What additive do you like to absorb the water?

 

[bronco italiano]

A9L was notorious for the stalling. The P, not so much. And because all the cool kids had A9Ls, I had to have that one myself. Natch. It's now resting comfortably on my office desk, having been replaced by a reflashed Explorer PCC1 that does things it could't, and without external hardware.

That is supercool. But even if I had that ecm, isn't it now illegal to reflash?

 

[ksagis]

Wht is programmed idle speed for A9P and A9L? Assuming auto is lower? And if lower, lack of VSS signal would be more impactful?

Seems to me the specifics of the install are important and if changes in baseline hardware have been done (like going to auto tranny but still using A9L).

edit: added some of the differences between A9P and A9L in programming.

 

[ksagis]

A9L was notorious for the stalling. The P, not so much. And because all the cool kids had A9Ls, I had to have that one myself. Natch. It's now resting comfortably on my office desk, having been replaced by a reflashed Explorer PCC1 that does things it could't, and without external hardware.

Wasn't this more related to the timing curve than anything else?

 

[lars]

As I understand it (EFIGuy will know for sure) an A9L can be turned into an A9P with the Quarterhorse except for the difference in the neutral/drive switch wiring. What I experienced was when pushing in the clutch while rolling to a stop, the engine would instantly drop to idle speed. Sometimes a little below, then catch itself and stabilize. Except when it didn't. And it died. With the VSS, I observed that when I pushed the clutch in while approaching a stop, the idle would hang a little high- maybe 100 rpm or so- until I came to a complete stop. Then it would settle down.

I learned my way around Binary Editor when I ran EEC-IV, mostly using a Tweecer, but I didn't change much. It was primarily so I could enable EDIS, secondarily to take advantage of the cam I had. I switched to a Quarterhorse a few years ago, then made major changes to run the 408. EEC-V came about mainly because I pulled the NV4500 in favor of a 4R70W and I didn't want a standalone transmission controller. I was interested in the challenge of using the Explorer stuff (maybe I'm a masochist).

You should check for codes. Not all of them will turn the check engine light on.

As for reflashing, that's a gray zone.

 

[EFI Guy]

Since this has been running fine with a custom tune for many years, the last thing you should do is touch the throttle stop screw. Your idle air settings were likely tuned for the position it's in, so it should never be touched again. Something obviously changed and it isn't likely to be the throttle stop. I would check for vacuum leaks and clean the IAC.

VSS is critical to have with a manual transmission, but far less important on an auto.

Reflashing itself is not illegal. PATS programming / deleting, gear and tire recalibrations, and a handful of other things are perfectly fine. The issue is if you reflash to remove emissions devices. The feds have decided there is no longer an "Offroad Use only" exemption. So if the vehicle or engine had emissions devices from the factory it has to have them forever, even if it never sees pavement.

 

[bronco italiano]

Thanks Mr. Vance.y eb actually performed smoother after you made the chip from the AED/Clint Garrity tune. All has been flawless. Am I able to datalog the ecm with the chip you made and have you review it if this issue happens again?

 

[bronco italiano]

Update:
Finally had the opportunity to use the seafoam spray at the throttle body, right nest to the IAC port.
Let it soak for 10 minutes, Drove it like I stole it (up to 5,000 rpm).
Idle at a stoplight with brake on about 675
idle in park- about 750
No hiccups, or stalls. However, the bronco life is a dynamic state of love and frustration so time will tell.
Thank you all for the guidance/wisdom. Will update as I drive more.
BI

 

[73azbronco]

do you use one of those oil impregnated air filters? Ditch it.

 

[bronco italiano]

do you use one of those oil impregnated air filters? Ditch it.

No, only Wix through a 1991 Mustang airbox

 

[73azbronco]

No, only Wix through a 1991 Mustang airbox

huh, usually dont hear of mafs getting dirty unless its like 100,000 miles of dirt

 

[bronco italiano]

huh, usually dont hear of mafs getting dirty unless its like 100,000 miles of dirt

Didn't clean the MAF, just from the TB inward. I too am not sure if the IAC is the real culprit given the stutter I had while driving and not coming to a stop. Bronco life lives on, I am just EB stupid crazy

 

[ksagis]

Didn't clean the MAF, just from the TB inward. I too am not sure if the IAC is the real culprit given the stutter I had while driving and not coming to a stop. Bronco life lives on, I am just EB stupid crazy

I always thought products like that wouldn’t do much, could you describe a bit more what you did, just spray or do the oil/gas application?

And did it completely clear up the stalling when coming to stop?

 

[bronco italiano]

I always thought products like that wouldn’t do much, could you describe a bit more what you did, just spray or do the oil/gas application?

And did it completely clear up the stalling when coming to stop?

The process of the sea foam spray was mainly for direct injection cars. It fogs the system from the throttle body butterfly inward.
These products do help clean/lubricate the upper system, back when I was a kid, my dad would ALWAYS listen to KNBR radio station and he would use water and brake fluid mix down the carb on with F100 once a year. He had to up the idle to about 1500rpm, once there was 2oz left he would dump the rest and the truck would die. Let it soak for 20 minutes and drive it for 30 minutes spewing white smoke like crazy. It cleaned the combustion chambers. Truck had 220k on it and ran like a charm when I sold it in 1999.
The dyno tuner at Panella racing engines said he always does a marvel mystery oil fogging (about 4 oz) if his engines are going to sit more than two weeks to prevent corrosion.
I don't use it in gas, I only use Chevron 91 octane because I am 10:1 CR.
Haven't driven since the last report and Stockton has been miserably hot too, don't want the bronco to get a sunburn. LOL