Automatic 3.0: Runs normal but engine stalls when shift into neutral while rolling

[nobb]

This is a very weird problem. The truck starts, stop, and runs 100% fine. But I noticed that if I am driving at a low speed (~20-30 km/h) and shift into neutral while braking, the engine will get into a stall as I'm slowing down. Since this truck is an automatic, this doesn't really affect normal drivability because it's not a situation that normally happens. But it does seem weird, so I'm wondering if someone could comment if this is normal behavior?

Is there anything I can try to diagnose? Truck runs fine with no check engine light or anything.

Thanks.

 

[Dirtman]

Ok i just gotta ask... why are you shifting an automatic into neutral while braking?

 

[nobb]

Ok i just gotta ask... why are you shifting an automatic into neutral while braking?

I'm not, that's why I'm saying it's not a normal drivability issue. I just happened to discover this and it's bugging me why it would stall out like that...doesn't seem right.

 

[Dirtman]

My guess would be the transmission is confused by the action and is either not releasing the converter clutch properly when you make the shift to neutral, or its simply turning the truck off because it thinks your drunk?

 

[Tater55]

My guess would be the transmission is confused by the action and is either not releasing the converter clutch properly when you make the shift to neutral, or its simply turning the truck off because it thinks your drunk?

I was fixing to say I do this all the time, then I saw the “automatic” part

Maybe a vacuum leak? My dads 98 3000GT does this as well. But his vehicle is a manual. Haven’t dug into it.

 

[cbxer55]

Thing is, if you're that close to idle that you're rolling to a stop, the converter clutch has already released. On all three of my Ford's, the clutch doesn't even lock up til around 40 mph. And depending on terrain, it'll kick the clutch off, even at 50 mph. And when speed falls below 40, or maybe 35, I can see the tach become more active as the clutch releases. My Ranger used to unlock the clutch, and shift out of OD just going up a hill. Then I changed to 4.10 gears, and it stays in OD and locked up on hills. My Ranger doesn't have a tach, but thanks to a loud intake and exhaust, I can hear when the clutch locks up or unlocks. Especially windows down, which they usually are, even in rain.

As for neutral, I shift into neutral at all nap-inducing stop lights. When in neutral, the trans fluid does nothing more than go out to the cooler and back to the pan. It allows the oil to cool down some while you're sitting there catching some ZZZZs. My friend Rick, who owns ACE Transmissions in Midwest City OK, says it's really good and helps extend transmission fluid and transmission life itself. Been doing it for years, btw. Read it in some old magazine years ago. And yes, sometimes I shift it into neutral as I'm coasting the final few feet to the nap spot. Never had a problem doing it, in any of my vehicles.

 

[NIGERIAN RANGER]

I'm thinking might be a torque converter issues or something?

 

[55trucker]

Does this situation occur all the time or only when the engine is warm enough for the fuel system to closed *closed loop*?

 

[cbxer55]

I fail to see how it could be a torque converter issue if the truck is in neutral.

 

[RonD]

This is a very weird problem. The truck starts, stop, and runs 100% fine. But I noticed that if I am driving at a low speed (~20-30 km/h) and shift into neutral while braking, the engine will get into a stall as I'm slowing down. Since this truck is an automatic, this doesn't really affect normal drivability because it's not a situation that normally happens. But it does seem weird, so I'm wondering if someone could comment if this is normal behavior?

Is there anything I can try to diagnose? Truck runs fine with no check engine light or anything.

Thanks.

Try shifting into Neutral AFTER you are stopped, does it stall or stumble?

If you shift into Neutral and coast to a stop, NO brakes, does it stall?

If you have a tachometer what are the RPMs at when moving and shifting into Neutral?

One of the main fuel savings techniques of fuel injection is that injectors can be shut off when coasting in gear
So when you take your foot off the gas pedal while moving, injectors shut off until RPMs are under say 1,200 then computer starts them again at idle levels
Computer will add fuel now and then to keep Cats hot
But when throttle is closed and you are coasting in gear the engine doesn't need any fuel

"In gear" for a 1994 automatic(A4LD) is determined by the NSS(neutral safety switch) on drivers side of transmission, above shift rod
See if you can start the engine in Neutral
That will tell you if NSS is OK
You should be able to start engine in Park or Neutral if NSS is OK


Power brake booster leak
If it only stalls when using the brakes then could be vacuum leak in booster

 

[55trucker]

If the converter clutch plate bearing in the converter is going away then the clutch can *wobble* causing an intermittent situation where the lockup *grabs* under all conditions (one will usually hear a metallic knocking noise from the converter as well). If the hydraulic control valve pressure to the the converter clutch is sticking *on* then the clutch cannot release properly as well. If one is experiencing this when it happens one shuts down the engine & restarts it the clutch issue magically disappears until one puts the trans back into drive again.