4L Powertrain Problem
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Post Fiend
Joined: Apr 2005
Posts: 5,720
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From: Washington state
4L Powertrain Problem
since last fall on vacation, the Aero 4L has been having an intermittent jerk stumble problem on hills, freeway on ramps under medium load in 3rd 4th and LU. had noticed a 10>20% drop in fuel mileage. ran fine on freeway cruise, steady speed, around town. problem not always present
no codes. nothing on scanner.
thought it was a transmission problem either lockup clutch or OD band slip/grabbing. band or clutch bad or valve body problems.
researched it all winter thru bad weather. part of 4L OBDII EEC-V PCM algorithm is to drop out of TC LU or drop a gear down when a power/miss problem is detected. will upshift and/or go into LU when problem clears
apparently cycles quickly
resolution:
did the easy shot in the dark repair first. replace the spark plug wires. old ones only had 30k on Motorcraft. must have damaged one wire while replacing lower intake manifold gaskets last fall.
runs perfect now, full power, no shift jerking, gas mileage back up.
researched. AC Delco now has the manuf. contract on Motorcraft plug wires at plant in Mexico. replaced with AC Delco 8MM full silicone, exact lookalike for MC and less money
bonus; solved the ignition noise problem since new in radio on AM band with 3 sets of plug wires
no codes. nothing on scanner.
thought it was a transmission problem either lockup clutch or OD band slip/grabbing. band or clutch bad or valve body problems.
researched it all winter thru bad weather. part of 4L OBDII EEC-V PCM algorithm is to drop out of TC LU or drop a gear down when a power/miss problem is detected. will upshift and/or go into LU when problem clears
apparently cycles quickly
resolution:
did the easy shot in the dark repair first. replace the spark plug wires. old ones only had 30k on Motorcraft. must have damaged one wire while replacing lower intake manifold gaskets last fall.
runs perfect now, full power, no shift jerking, gas mileage back up.
researched. AC Delco now has the manuf. contract on Motorcraft plug wires at plant in Mexico. replaced with AC Delco 8MM full silicone, exact lookalike for MC and less money
bonus; solved the ignition noise problem since new in radio on AM band with 3 sets of plug wires
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