91 erra 740 and 940 strange findings

[rwturbo]

Ok I have stumbled across something that seems to only be in the 91-92 erra of automatic turbo cars. I have stripped harnesses from these cars and retrofitted lots of older cars with the set up. I also have access to Mitchell's and all data. Was brought to my attention that when you shift these model cars into gear they idle up a hair. And you only have to barely move the shifter and not actually change gears and the tach comes up. Seen it with one car then another and now I'm at 4 that do the same thing in that year range. With zero ties to the engine management system of the neutral safety switch (pnp). Any of you guys have a car in that range ? It don't do it on older or newer cars. Like said don't move the selector into gear just barely nudge it and see if your rpm raises about 150. I'm lost at how and why. I know these cars inside and out but missing something. Last car was a stick we swapped to auto and all the factory wiring was there so no hacking was done. Damn it did it also. Something in that year range is being told by the pnp that the car is out of park and out of neutral. Just no schematics to back it. Let me know if you guys encounter same issues with said year range of cars. Thanks.

 

[lummert]

Could it be because you've put your foot on ther brake pedal?

 

[turbotankshane]

There are two different tables in lh2.4 ecu's for idle speed, one for p/n (only table used for manual cars) and one used for all the rest

 

[BrianB]

Play with the AC switch, though this is supposedly not an issue with LH 2.4, just 2.2