Cougar with misfire on #3 & #5

PO'MAMA

MEMBER
MERCURY COUGAR

I have a 97 Cougar XR7.V6.100,000 miles. In Dec. I had to get a longblock put in, because of bad gasket and bad rod and bad trouble. It ran good for one day. There was extreme shaking and not wanting to move. So I went to "Firestone". The codes showed misfire on 3 and 5 so they said I needed an ignition coil and plug wires. Okay did that.$475.00. The car started shaking again. Light again came on. Same code as before (P0352). "Firestone" wasn't able to find out what the problem was because they said it had to be doing it at the time they checked the car. I have been there approx. 10 times in the last two months, and then yesterday it was worse so I got them to actually look at the car. They said the coil they put in had a weak spark. Okay. They replaced that ignition coil with another. Within one hour the car was shaking severely, light was on again. Next day I head back to "Firestone" (after 4 hours) they tell me they finally got it to mess up and they said "the PCM is losing its ground" and I will need to replace the PCM. Thats $590.00 I don't have. Shoot I'm still paying off the $475 PLease help with any info.

9 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Well if it's true the pcm is faulty try a boneyard and put in used one. After all that money seems a ford dealer could tell you pretty quick?

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Thursday, March 8th, 2007 AT 2:27 AM

PO'MAMA

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6 POSTS

Which is the best book to give details on how to do replacement. Can an individual do this without the big equipment to get the car restarted? Thanks for your help

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Thursday, March 8th, 2007 AT 9:33 AM

MERLIN2021

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First I would get it tested by someone competent, forget firestone, even if you paid ford a hundred bucks by now you would be waaaay ahead. If you want to do it yourself not too hard. I would walk into autozne take a quick look in the Haynes or Chilton book and go to it. I would first make sure I needed it! Anoter point, who put the longblock in?
Are you shure you actually got a complete engine, heads and all?

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Thursday, March 8th, 2007 AT 2:02 PM

PO'MAMA

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Midwest engine in Tulsa, did the longblock. They have even tried to help but the problem has been electrical not mechanical. I'm still under warranty so they have checked everything a couple of times.I just found a PCM at salvage yard and need to know if I change this myself will the car function when its put in?

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Thursday, March 8th, 2007 AT 5:00 PM

MERLIN2021

MECHANIC
17,250 POSTS

If you get it from same make model and engine displacement yes. By looking at it you tell me? If you tackle it take negative battery cabel off first! I think the toughest challenge you will face is locating it!