Automatic vs. Manual SMEC - any hardware differences?

[jonnymopar]

Just as the title says. Are there any hardware differences, or are they simply code changes? Thanks.

[A.J.]

Nope. Just code.

[turbovanman²]

Things like neutral safety switch's are set up differently between auto and 5 speed but if simply swapping the computer, then slight programming tweaks.

[jonnymopar]

Interesting. I'm asking because of a post that I ran across yesterday. Something about if you run a 5-speed car with an automatic ECU, there's the possibility of it dying out at stops. I've been having this issue with an aftermarket cal, and I've figured out that if I don't put the clutch in until the last minute (basically the tach is almost at idle), then it doesn't happen. If I'm driving along and I just randomly put the clutch in, the car dies instead of dropping to idle.

[A.J.]

Interesting. I'm asking because of a post that I ran across yesterday. Something about if you run a 5-speed car with an automatic ECU, there's the possibility of it dying out at stops. I've been having this issue with an aftermarket cal, and I've figured out that if I don't put the clutch in until the last minute (basically the tach is almost at idle), then it doesn't happen. If I'm driving along and I just randomly put the clutch in, the car dies instead of dropping to idle.

All SMECs are the same. The only differences are the calibrations put on them. The manual calibrations hold the idle a little higher a little longer on decel. Even with an auto cal, your car shouldn't die on decel. If your car is dying you might have an AIS motor problem. It's not a SMEC problem.

[ajakeski]

Check for codes.
My GLH was dying at stops and the issue was the vehicle speed sensor.
A new speed sensor fixed the problem.

[turbovanman²]

Interesting. I'm asking because of a post that I ran across yesterday. Something about if you run a 5-speed car with an automatic ECU, there's the possibility of it dying out at stops. I've been having this issue with an aftermarket cal, and I've figured out that if I don't put the clutch in until the last minute (basically the tach is almost at idle), then it doesn't happen. If I'm driving along and I just randomly put the clutch in, the car dies instead of dropping to idle.

Mods? It might need the throttle plate opened up a bit.

[iTurbo]

I would say it definitely sounds like a faulty vehicle speed sensor with regards to the stalling when coming to a stop.

I have also run an automatic SMEC on my GLH Turbo (with manual trans). If anything, it seemed liked it idled a little higher when coming to a stop than it would with a manual SMEC.

[jonnymopar]

Is it possible for the speed sensor to go bad, but have the speedometer/trip still work?

[shadow88]

I would just keep driving it. My car will stall at lights for a few days after swapping computers or battery disconnects. It clears up in 3 days and it's fine unless I let it sit for more than a couple weeks.

[A.J.]

Is it possible for the speed sensor to go bad, but have the speedometer/trip still work?

Year, make, model, drivetrain? Some years/models/drivetrains used a cable.

[iTurbo]

Is it possible for the speed sensor to go bad, but have the speedometer/trip still work?

Definitely possible, although like A.J. said it depends on models/years. Generally cars up to '90 or so used the cable to drive the speedometer/odometer/tripmeter. The VSS itself is used by the computer. Later years did away with the cable (like my Spirit R/T) and used the VSS for everything; computer input and speedometer.

[bgbmxer]

Something simple to do that helped me before you go spending money swapping parts is set the base idle. My car would do the same thing this fixed it right up.

[jonnymopar]

No cable for me. Only the VSS on all the cars I've had (three Daytonas, two 88's and an 89). I'll play around with the throttle body tonight and see if I can just mechanically increase the idle slightly without freaking everything out. I've been tossing around the idea of switching to a 58mm throttle body off of a 3.8L van, so I can certainly mess with it then.