Part Throttle Unlock (auto trans LU converter) discussion & theory

[cordes]

I'll look at the PTU code in the '95 Neon. Maybe it's the same code and just a better calibration. Maybe it's completely different code...

For reference, mine is a 97. I'm really interested to see what you find. I would really like to have a lockup converter in my Newyorker with the .91 transfer gears. I think I could get over 30mpgs reliably on the freeway that way.

[ShelGame]

The '95 Neon lock-up code is identical to, well everything else I've looked at. So, Chrysler didn't change the LU code from '87 (1st SMEC application in minivans) up thru '95.

The Neon calibration values are a little bit different from the other models, but not radically so. The most interesting part is that they don't allow lockup while coasting (IE, off throttle). Newer cars with automatics do so that you can use decel fuel cut (without killing the engine) for FE improvement. In our current cals, only the manual trans cars have decel fuel cut turned on. That might take some experimenting with calibration values, but I would think we could implement it...

Decel fuel cut is one of the things I'm adding to the next T/SMEC. It will be lifted completely from the SBEC code (it's factory code in the SBEC).

[ShelGame]

Well, I finished up my update to T/SMEC. I think I might have the rotating spark cut staging limiter working now, just need to verify it on my car (probably Saturday). If it all works, I'll post it over the weekend.

PTU is fixed, changed the names of the TPS tables to make it more clear. And, the lock-up is not really primarily controlled by TPS, it looks more like it's load controlled. There's a TPS element, but I think that's mostly because TPS is the fastest way to sense a change in load conditions. There are also MAP and Speed related lock-up values. I'll have to go thru it again to see exactly what/when they are used.

I've also added the Decel Fuel Cut (pasted directly from the Chrysler SBEC code). But, it currently only works for manual trans cals. I suppose you could setup a MT cal and use DFC with an auto that way. But, I want to think about how to use DFC with an auto in conjunction with the lock-up solenoid as I think that's a better way to do it.

Does anyone know which gears in the A413 have overunning clutches? Only 1st? Or 1st and 2nd? Any gear that has an overunning clutch has the risk of engine stall if DFC is used.

[RoadWarrior222]

Hmmm I've got a feeling that the reply to that last question is "it's complicated" on account of varying mods. i.e. accumulator delete.

[turbovanman²]

Good memory Alan, I just use a toggle switch, as around town a LU is useless plus its nice when drag racing to turn it off.

Well, I finished up my update to T/SMEC. I think I might have the rotating spark cut staging limiter working now, just need to verify it on my car (probably Saturday). If it all works, I'll post it over the weekend.

PTU is fixed, changed the names of the TPS tables to make it more clear. And, the lock-up is not really primarily controlled by TPS, it looks more like it's load controlled. There's a TPS element, but I think that's mostly because TPS is the fastest way to sense a change in load conditions. There are also MAP and Speed related lock-up values. I'll have to go thru it again to see exactly what/when they are used.

I've also added the Decel Fuel Cut (pasted directly from the Chrysler SBEC code). But, it currently only works for manual trans cals. I suppose you could setup a MT cal and use DFC with an auto that way. But, I want to think about how to use DFC with an auto in conjunction with the lock-up solenoid as I think that's a better way to do it.

Does anyone know which gears in the A413 have overunning clutches? Only 1st? Or 1st and 2nd? Any gear that has an overunning clutch has the risk of engine stall if DFC is used.

I might try the new code when I get the van back.

The roller clutch is held in 1st only when the selector is in D, in manual first, its not held but the low/reverse band is.

[A.J.]

I adjust Baseline fuel for decel fuel cut. I had it adjusted perfect with my 2.5. Cruising at 40 or faster, let your foot off the accelerator, and fuel cut. Air fuel ratio went to 20 (open air) on my wideband. I'm having trouble getting it right with my 2.4.

A.J.

[ShelGame]

I adjust Baseline fuel for decel fuel cut. I had it adjusted perfect with my 2.5. Cruising at 40 or faster, let your foot off the accelerator, and fuel cut. Air fuel ratio went to 20 (open air) on my wideband. I'm having trouble getting it right with my 2.4.

A.J.

Does it ever cause an engine stall with the auto trans?

[A.J.]

Does it ever cause an engine stall with the auto trans?

Never. It's seamless. If it wasn't for my wideband going to 20 or my narrowband going flat you'd never know it was cutting fuel. I can post my 2.5 cal if you'd like to see it. You need to tell me how to make a zip file though, I've never done it before.

A.J.