RPM surge and electrical surge; voltage regulator?

YellowJacket
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Posts: 3
Joined: Sat Apr 29, 2017 2:28 pm

RPM surge and electrical surge; voltage regulator?

Postby YellowJacket » Sat Apr 29, 2017 2:46 pm

2005 Freestyle SEL AWD with 196,000 well cared for miles. Experiencing engine RPM surge at idle and low speeds along with possibly related electrical surges that cause dash lights and headlights to brighten and dim, needle gauges to periodically flat-line, and AC motor to sometime shut off. Alternator was replaced at Ford in 2014 and has checked out as OK three times in March and April. Battery was replaced in 2014, and again this month (under warranty) after three dead battery incidents. Throttle body was replaced in 2011. Induction system was fully cleaned and serviced last August by Ford, and PCM reprogrammed after a more pronounced but separate engine surge problem had me close to taking out pedestrians. Removed and cleaned throttle body last weekend, and replaced PCV valve. Local shop says car is experiencing electric surges that reach 19 volts. They tell me that this alternator does NOT have a voltage regulator, but that the alternator output is controlled by cars computer. Local auto parts store seems to back this up by saying they do not show a voltage regulator for this model. Can anyone confirm I cannot just replace the voltage regulator on the alternator (for a cost savings). I don't want to spend $140 on a remanufactured alternator if it won't resolve, or $150-350 for engine control module that has to be coded to my VIN just to see if it will fix. Spoke with local Ford service advisor, who conferred with his shop forman, who did not recommend bringing such a high mileage car in for testing. Said he would have to charge straight bench time for what could be extensive testing that may not point to the cause. I am not getting any check engine or check charging system dash lights, so seemingly no error codes to point to cause.


YellowJacket
New Member
Posts: 3
Joined: Sat Apr 29, 2017 2:28 pm

Re: RPM surge and electrical surge; voltage regulator?

Postby YellowJacket » Mon May 15, 2017 10:55 am

Update: I pulled the alternator and had it bench tested at the local O'Reilly Auto Parts. Three consecutive tests all showed it fine. So I ordered a refurbed powertrain control module (PCM) from Flagship One in New York ($228 vs. $1,200 from Ford). It arrived one week after I placed my order, software updated and programmed to my VIN number, with two uncut keys already programmed to the PCM. I've only had it out for one day of test drive, but the problems (RPM surge and voltage surge) both seem to be resolved. The local auto parts tested the voltage output, and it was back in the normal range.


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