2 questions

what parameter didctates how long an engine runs at fast idle after starting up and to what rpms does it have to run

next question concerns what parameter increases engine rpms when downshifting. here is the scenerio.....you are running along at say 45 and approch a stop so you downshift (automatic) into 3rd than 2nd, when tach reacehs 1000rpms it will suddenly surge to 1500rpms. so now you have to apply more brakes cause the motor just sped up. it will only do this 1 time until the next time you repeat the process.

my reason for asking this is because i had Ed Wright at Fastchips cut me a prom and i have asked him repeatedly about this but never get an answer, just that he has been doing this for 26 years and does not know of anything. my car is in perfect shape and has had 3 GM proms and they all do the same ting.

can anyone help me

thanks
Terry in Orlando

 

1. Generally speaking, there will be a table in the PROM that deals with idle rpm vs. coolant temp. It should idle wherever the instructions tell it to.

2. The other sounds to me like a mechanical problem - maybe a vac leak, or a leak from the CCP at low MAP.