wont start after PCM replacement

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Mar 2, 2010 | 03:43 PM

dgpach

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wont start after PCM replacement

Hi, I need some help! It's a 2000 Expedition 4X4 Auto with a 5.4L. Started having problems with CEL (sensor1 bank1 reading lean). Swapped out the O2 sensor but no change. Dealership said it was a bad set of wires between O2 sensor and PCM, so I replaced these wires. Dealership also said that the PCM had problems. I've tried two replacement PCM's, but the engine won't start after installing either of them. Cranks strong, but no firing. Everytime I put my original PCM back in it runs fine, but I get the CEL which wont let me pass smog. Do I need to reprogram something after swapping the PCM?

Mar 2, 2010 | 04:43 PM

powersmoked

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From: Boston, MA

i don't know about the swapping pcm stuff. I do know that a lean code p0171. is not a bad o2 sensor. the sensor is doing it job. since you only have a lean condition on one head you probably have a vacuum leak on that head.

Mar 2, 2010 | 05:23 PM

dgpach

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Thanks, I agree with your suggestion, but the stealership charged me a lot of money to tell me it was either the O2 sensor wiring or the PCM. Is there any way you can think of to richen up this bank with propane to confirm that I can get > 1/2 volt out of this sensor / wiring harness? If they are right (a big if) I should focus on the sensor wiring / PCM otherwise I'll check for vacuum leak, faulty injector / coil pack etc. Are there typical spots for leaks on this bank (bank 1 )?

Thanks for your help !!!!

Mar 2, 2010 | 06:02 PM

projectSHO89

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From: St Louis

You cannot swap a PCM on a PATS-equipped truck without having the system reprogrammed by a dealership.

If you try it, you will trip the factory anti-theft system and it will never start.

Mar 2, 2010 | 07:04 PM

dgpach

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Thanks all for your helpfull advice. I'm going to rule out vacuum leaks etc first and leave the PCM replacement and Stealer visit for reprogramming to the last.

Dont't get me wrong I think this and other Ford products are best in class (I used to work for them) BUT

Think about it....... In order to prevent my vehicle from being ripped off they designed it so that I can't swap the PCM, but have to go to the dealer so they can rip me off.

With a $200 Vag Com I can change almost anything on my Audi's and become informed about the intimate performance details of all the control modules.