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2003 ford expedition 4.6 4x2. THIS VEHICLE CAME IN WITH AN ...

Sent to Car Experts June 30, 2006 6:11 p.m.

2003 ford expedition 4.6 4x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

Optional Information:
2003 Ford EXPEDITION 4.6

Already Tried:
NEW PCM AND MULTI CIRC AND GROUND TEST.

Customer (name blocked for privacy)

Status: Closed Value: $25

Answer
June 30, 2006 8:06 p.m. (1 hour and 55 minutes later)

REPLIED

2006-06-30_195324_1.pdf

The link above should show the schematic for the injectors. They all have the same power source. And the Pcm grounds each injector internally so if you are losing ground only on a few of the injectors It could be that you have a wiring harness problem. Try wiggling the injector and pcm harness while the truck is running. Second it could be that you have a pcm ground problem and all the grounds for the pcm should be checked. I have posted most of the grounds but really think you will find a harness problem. Look especially close at the harness behind the engine that lead to the coils. At worse you could pick out one of the bad circuits and run an overlay to ensure the problem is in the wiring. Takes only a few minutes to overlay the circuit from the pcm to a coil.

2006-06-30_200551_1.pdf

2006-06-30_200600_2.pdf

2006-06-30_200608_3.pdf

2006-06-30_200632_4.pdf

2006-06-30_200640_5.pdf

Edited by tactgear1 on June 30 2006 at 8:10pm

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Senior Master Subaru, G.M.Cert.,Honda cert., Dodge Cert., Ford Cert., 2 ASE Master cert.15 yrs exp.

Reply to Danny
Sent July 05, 2006 4:04 p.m. (4 days and 19 hours later)

We are trying your advice today and if all goes well we we'll let you know. Thanks.

Customer (name blocked for privacy)

Answer
July 05, 2006 4:28 p.m. (24 minutes and 19 seconds later)

REPLIED

let me know what you find or if you have a problem with files.

__________________
PLEASE -Remember that your Expert will not be paid until you accept an answer and complete the process. Please leave "FEED BACK".

Danny -- Shop foreman -- 99% Positive Feedback on 331 Car Accepts
Senior Master Subaru, G.M.Cert.,Honda cert., Dodge Cert., Ford Cert., 2 ASE Master cert.15 yrs exp.

Reply to Danny
Sent July 13, 2006 9:09 a.m. (7 days and 16 hours later)

YOUR ASWER DID NOT HELP. WE FOUND 1 COIL SHORTED THAT WAS BACK FEEDING AND SHORTING 3 MORE COILS SOMETIMES. THANKS FOR THE TRY...

Customer (name blocked for privacy)

Answer
July 13, 2006 10:37 a.m. (1 hour and 27 minutes later)

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Danny -- Shop foreman -- 99% Positive Feedback on 331 Car Accepts
Senior Master Subaru, G.M.Cert.,Honda cert., Dodge Cert., Ford Cert., 2 ASE Master cert.15 yrs exp.

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