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engine problems


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wolfpack
User
wolfpack profile image

Sep 20, 2011, 7:23 AM

Post #1 of 12 (1816 views)
engine problems Sign In

my girlfriends has a 1995 mercury cougar 3.8 120,000 miles. It has a mind of its own. Every now and then the motor will stumble and acts like it wants to die it don't do it all the time sometimes it will go a week before doing it other times its every day. The other day the tach showed zero and the car was still running i gave it gas and the tach came back this car has been great till jan i replaced plugs,wires,cap&rotor,iac x2,egr valve,egr sensor,coil,icm,cleaned the mass air flow sensor (i tested it and it showed ok), fuel filter and pump. no codes just driving me crazy cant figure it out don't make sense can anyone help please i need my sanity back lolCrazy


DanD
Veteran / Moderator
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Sep 20, 2011, 8:24 AM

Post #2 of 12 (1789 views)
Re: engine problems Sign In


Quote
The other day the tach showed zero and the car was still running


Just guessing here but I’ve seen an intermittent shorting tachometer cause stalling and or issues that you’ve described?
The hard part will be finding where they sliced in the tach signal wire (white/pink), too the orange/white wire that runs between the ICM and the PCM. My wiring diagrams for these years of vehicles don’t give me splice locations; so it’ll be a game of search and rescue? You cannot just cut the orange/white wire the PCM needs this rpm signal. Once you do find the white/pink wire splice; cut it in an area that will be easily repaired; if this is not the problem.
I guess you could also go to the back of the instrument cluster and disconnect the white/pink wire there? You’ll find it in connector 1, terminal 18. The only problem with disconnecting it there is; it won’t prove out that the white/pink wire itself doesn’t have an intermittent short to ground?
Remember this is just a guess; but if you’re confident you’ve done all those other things properly; what’s ya gots ta loose?

Dan.

Canadian "EH"






wolfpack
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Sep 20, 2011, 9:02 AM

Post #3 of 12 (1781 views)
Re: engine problems Sign In

thanks im pretty machanically enclined plus i learn real quick. Was just hoping it wasnt a wiring prob they take for ever to find thanks for your reply im starting on that tonight (had a feeling a wire)


Hammer Time
Ultimate Carjunky / Moderator
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Sep 20, 2011, 11:46 AM

Post #4 of 12 (1772 views)
Re: engine problems Sign In

Why don't you try cleaning the throttle body before diving into the electrical circuits. It may or may not help.
First eliminate all vacuum or air leaks in the system. Try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



DanD
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Sep 20, 2011, 2:33 PM

Post #5 of 12 (1761 views)
Re: engine problems Sign In

That is a good solid suggestion to clean the throttle plates; it sure won’t hurt anything doing so and it could very well help.
The reason I went tach is because the poster said that it had dropped to zero but the engine was still running. And like you already know the tachs in these years of Fo.Mo.Co’s were still fed live primary ignition sense; not serial data from the PCM.
Again like I said before, just a guess on my part; I just wanted to clarify why I suggested that route.

Dan.

Canadian "EH"






Hammer Time
Ultimate Carjunky / Moderator
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Sep 20, 2011, 3:08 PM

Post #6 of 12 (1754 views)
Re: engine problems Sign In

He may end up having to go that route anyway but he also may have misinterpreted what the tach was doing so the cleaning is a good place to start.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



wolfpack
User
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Sep 20, 2011, 3:47 PM

Post #7 of 12 (1750 views)
Re: engine problems Sign In

Thanks for the replys i already cleaned the throttle body when i changed the tp sensor. Someone stripped the heads of the screws so i had to take off the throttle body to change it. Yes i do understand the tach i just don't understand why one week the car runs great no problems.Then all of a sudden she feels like she is going to die she stumbles when coming to a stop sign/light i give it more gas so she wont die or throw it into neutral for a sec. But hers the funny part, it might only do it once in a 20 min drive then be fine for 2-3 days then do it again 3x the 4th day during a 20 min drive thats why i said i need my sanity back thanks guys your help is greatly appreciated thanks againSmile


Mr.scotty
Enthusiast
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Sep 20, 2011, 6:04 PM

Post #8 of 12 (1737 views)
Re: engine problems Sign In

Did you do as hammertime said and check for vacuum leaks?
That would be the next thing I would look for.
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Your only as good as your tools!


DanD
Veteran / Moderator
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Sep 20, 2011, 6:11 PM

Post #9 of 12 (1736 views)
Re: engine problems Sign In

Well good luck to you; intermittent issues are the hardest to cure. Just don’t forget the basics and continue to recheck the things you know (think) are not the cause; something may pop up and make you say how did I miss this?????

Dan.

Canadian "EH"






wolfpack
User
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Sep 20, 2011, 8:14 PM

Post #10 of 12 (1727 views)
Re: engine problems Sign In

yes i check all around the motor for a vacuum leak even did a vacuun test thought maybee cat was going bad but everything keeps checking out ok. Just a thought could the temp sensor cause this problem i know my 95 buick pa would act weird when my temp sensor went bad just a thought i know different makes & models


Mr.scotty
Enthusiast
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Sep 21, 2011, 11:37 AM

Post #11 of 12 (1720 views)
Re: engine problems Sign In

If you think it could be the ECT sensor then do a resistance test on it.
Heres the ohms chart for it:


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Your only as good as your tools!

(This post was edited by Mr.scotty on Sep 21, 2011, 11:38 AM)


wolfpack
User
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Sep 21, 2011, 1:11 PM

Post #12 of 12 (1711 views)
Re: engine problems Sign In

thanks for the diagram hopefully im in luck my girl was driving today and it finally set a code unfortunatley im out of town cant read it for a week thanks again everyone will let you all know what code it sent






 
 
 






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