What's up everybody, I need help. I have had a th400 in my car for ever and from day one the idle on occasions will idle up and idle down to the point of almost dying. I have been to a couple know tuning shops in my area and neither of them could eliminate the idle issue. So my question is am i stuck with it or can it be taken care of. I can't handle it anymore it makes me not want to drive it. Thanks for any advice i can get.

 

find a competent tuner or. I bet you have a big cam and low stall converter? why?

 

I don't have either, i have a 8in converter with a 4500 stall and a decent cam. It's a 408 N/A pump gas car with a/c.
The car is full weight the only thing missing is the spare tire. So it can be a tuning issue?? I was told it was cause by the th400 and the car was searching for a single. Please any help.

 

Anybody have any info??

 

Do you have a park neutral/switch connected to the PCM?

You need one if you don't have one.
And the turbo 400 speed sensor is connected and operating properly?

 

Not sure about the neutral safety switch but my speedo does not work. Could this be the reason?

 

I had that issue I had to up the base idle air flow if you have Hp tuners

Idle<airflow<base running airflow

 

There are tables in the tuning that reference a park/neutral signal and changes timing and spark. It's not just a switch to prevent you from starting it in gear.

I guess it could be tuned around.

I'm assuming you meant to say that the tuner says the computer is looking for a signal? Not single.

So you really need to find out what signal it's looking for.

Was it a stock automatic car? Does it have a stock shifter?

The only signal that the PCM needs to see to idle properly is the VSS. Everything else can be tuned around. The park/neutral signal would help. But there is no other transmission signal that needs to be present for the car to idle properly. So your tuner either doesn't know how to tune it properly or it's missing something that you don't know about.

I still don't understand why you can't post exactly what the tuner says the PCM is looking for.
That makes me think he doesn't know, or you forgot.

 

The only info the tuner said was it's gonna idle like that cause the th400 is searching for a signal. Never explained what signal. It was a automatic before and the shifter is a cheetah.

 

Thats pure BS. That tuner doesn't know what he's talking about.
Wouldn't hurt to connect the park/neutral wire up to the shifter switch. (again, not the one that keeps it from starting in gear).

 

I don't know much about wiring but i will definitely find someone to check it. Really appreciate the information. I really like the car just sucks to drive sometimes.