i have run through the idle learn process but often on a hot start the idle will jump to 3000rpm and eventually return to 800rpm. i noticed you guys in the US cut a few wires when installing a PFC. i can only assume the PFC is activating the AWS and assume i must cut the AWS wire.

also on cold start the engine will idle at 1700rpm until coolant temp reaches 80deg C. is this normal?

BTW i have adjusted the idle valve screw half a turn from closed

 

There are multiple tables and paramters affecting starting and idling. Only the DATALOGIT can adjust all of them.

First get the hot systems to work correctly and smoothly, then start on the cold systems.

The more modded an engine is, the harder it is to have the stock settings work correctly as the feedback loops are forced outside the range needed for stock.

I have to change my mechanical idle setting differenlty for winter and summer due to this.

 

thanks Chuck,

my FD is fairly close to stock. infact my mods match the recommended mods for the base mod map.

 

No, Datalogit can't adjust all settings

There is a table Idle RPM vs. Water Temperature, where idle can be set for -10C, 20C, 50C, 80C, 95C and 110C. For 80C and 95C it is by default set to use the values from the Rev/Idle settings.

That means the idle RPM (A/C Off, A/C On...) will only be used when the engine is at operating temperature, otherwise the other table will be used.

 

Same here.If the water temp is at 104C before start cranking,as soon as the car starts,the idle bounces 10 times up to 3000,and the goes to 800.....(no cutting to the wires).

 

The only NORMAL way starting can jump up to 3000rpm is if you are still running the AWS solenoid. Remove, and block it off. Then your idle can only bounce up to about 1500rpm.

Idle control smoothness is all in the adjustments of the two mechanical idle air settings in conjunction with the PFC settings.

If you all had grown up tuning multiple Weber carbs, then you would have a good basis for this stuff.

 

Remove your ISC and idle is set manually, no PFC to muck it up.

 

i removed the AWS plug and all is good so far.

as for the cold start idle, is this what the PFC is programmed to do?

 

The PFC mimics the stock ecu in startup functions.
The cold start and idle ECU controls are all feedback systems. If any adjustment or measured parameter is out of range or on the edge of going so, they will not function correctly. That is when you have to step in and make physical changes.

I assume that you never tuned cars with carburetors.

 

no fortunately i've never had to mess too much with carburetors.

though i'm aware of the the 2 idle adjustment screws and the therowax pellet. i have the cam type idle screw backed right off and the other idle adjustment screw half a turn from closed. haven't touched the thermowax idle

could you tell me roughly the correct voltage o/p for closed and full throttle?


(just a quick off topic question; how does the PFC base mod map handle a spike of 1.09kg/cm^2 or 15.5psi of boost?)