Stalls Out When Down Shifting To Stop

[Lscam580]

Did Hci and maf swap car will start run and drive. When I push in the clutch to stop motor stalls. Hit the key and will fire right back up or pop the clutch. Did a code check and no codes are present. Any ideas for a fix.

 

[FoxMustangLvr]

Please refresh our memory on what HCI work you just did? You say it starts, runs and drives but how well does it do all 3 of those? Running great?

Check your TPS?

 

[hoopty5.0]

I had a car that did that and was a bad MAF filament. However, when you did dump the codes, did you do KOEO and KOER?

 

[Lscam580]

Tfs heads , tfs upper and lower, tfs stage 1 cam, 1989 maf eec and full harness, never had an engine light come on since the swap. Every thing checks out good.

 

[Micheal Nadeau]

Sounds like it may be idled too low, when you push the clutch in and the rpms drop, it may be dropping too low to recover from. My car did this really bad when a/c was on. Brought the idle up a little and no issues since.

 

[FoxMustangLvr]

So from what Micheal is saying, you may need to do a base idle reset. Another thing to take into account is your computer is learning all the new mods you just did. You have to drive the car a few times, the longer the better each time.

 

[RacEoHolic330]

What did you do for the VSS input to the computer when you changed to mass air?

 

[Lscam580]

I'm new to this, what is a vss

 

[hoopty5.0]

What did you do for the VSS input to the computer when you changed to mass air?

You just unknowingly answered a question that has plagued me for years. I had no idea there was a VSS linked in with MAF cars. That would answer why the idle hangs while coasting and then settles when I stop, right?

and @Lscam580 VSS is vehicle speed sensor.

 

[FoxMustangLvr]

I think it's a speed sensor.

edit....Hoopty beat me to it by a few seconds.. carry on

 

[RacEoHolic330]

You just unknowingly answered a question that has plagued me for years. I had no idea there was a VSS linked in with MAF cars. That would answer why the idle hangs while coasting and then settles when I stop, right?

and @Lscam580 VSS is vehicle speed sensor.

Bingo. That happens by design.

 

[RacEoHolic330]

I'm new to this, what is a vss

It plugs into the driver side of the transmission. The speedometer gear is mounted to the end of it.

Unless your pre-mass air car had cruise control, you don't have one of these. The computer needs an input from this sensor to tell it that the car is moving. The computer users this information to hang the idle when you let off the gas. The idle is then slowly allowed to settle back down to normal. This prevents the stalling that you're talking about.