I am helping a buddy with his boat and want to check / set the timing on his 502 MPI. On the valve cover it says 8* BTDC at idle RPM. I know on the 500 EFI's a couple of wires in one of the plugs need to be jumped. Is this same type of thing required on the MPI's or can the base timing just be set at idle? Appreciate the help!!

Craig

Thanks for the post Vette, will get r done. Then we will be heading to the lake, maybe Wawasee for the Holiday weekend.

You have to set the timing in "Base Timing Mode". A code tool or scan tool is normally used for this. If you don't have a code tool, you can jump terminals A and B on the Data Link Connector.

Dave

In most cases you'll have to bump up the throttle a bit when doing this (say 1500 rpm) because there is no idle control from the ECM when you ground the pins. The the timing will read base at 1500 as well as 650 when this procedure is followed.
Very simple.
Dave

DaveN,

Do you ground pins A and B or connect them to each other?

Thanks

Appreciate the help. I know my way around "old school" motors pretty well, but these modern motors are a little tricky. Where is the data link plug located on the motor, or how can it be identified? I am ASSuming it is a distinct plug that should be pretty easy to identify. Are the pins labeled on the plug so A and B can be identified as well?

Craig

Pismo,
You connect them together. You can do it easily with a small paperclip as shown in the pic from link above.

Dave