Can a bad ECM cause low idle rmps?

Asked by E Aug 30, 2017 at 06:35 PM about the 1999 Mercury Grand Marquis 4 Dr LS Sedan

Question type: Maintenance & Repair

I'm having an issue with my alternator not charging
high enough while it's in gear if I'm stopped it will
drop to 12 volts charging while I drive it'll charge
between 13 and 14.2 volts. I've been having
charging issues for a while used a half-dozen
alternators finally ran a key on power from a new
source to the alternator and I'm not burning up
alternators now. Any ideas?

2 Answers

F_O_R answered 7 years ago

I would suspect the idle control valve. The valve is fairly easy to replace on the Triton engines. There is a Youtube video for this.

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E answered 7 years ago

I'll check it. Many auto professionals are confused by it's action. It acted like a bad regulator until I ran the alternate source for key on power. Now it charges ok until I sit at idle and it even gets worse if a/c is on. In gear at idle A/C and headlights on its at 11.8 if I'm lucky. I'll check the valve and see if picks up the idle. Thanks

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