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Discussion Starter #1
Like it says it cranks strong but won’t start. This started happening a few weeks ago when the temp drops below freezing. I am in the NY area so it has been cold! Most of the time when it warms up again it starts working. The car runs perfectly when it’s warm out. This has become highly frustrating. I changed the crank sensor and the ICM and the problem persists. The fuel rails show 40 psi, fuel pump primes for startup, noid light turns on with new injectors so not fuel. Used starting fluid in the intake with no start. Check engine light comes on when key is forward and there are no codes, so pcm has power. Like I said there are no issues when it is warm out. It seems to me that the computer is not commanding spark and I don't know why, any ideas?

Sorry I haven't posted in six months with my dyno tune numbers.
The car: 1995 4.6 cougar with 316 rwhp Trick flow pi heads, bbk tb/plenum, 2002 GT MAF, CAI, 190Lph fuel pump, aftermarket fuel rails, 24lb injectors, COPs with new spark plugs, kooks headers, true duals with x pipe no cats, T45 transmission, cobra brakes front and rear.

After the heads the car worked for 4-5 months without any problems so I don't believe it is tune related.
 

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Perhaps a bad connector and/or wires in/out of connector dealing with spark related components. The tipping point of which becomes the problem when the temp. drops to a certain level. Y'know that expand/contract thing.

I can't offer any specific advice other than visual inspections of wiring, and wiggle tests while cranking looking for spark from a coil like number 1.

That, and perhaps my post will get the thread rolling from those better in the know.:)
 

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Perhaps a bad connector and/or wires in/out of connector dealing with spark related components. The tipping point of which becomes the problem when the temp. drops to a certain level. Y'know that expand/contract thing.
This is likely; I'd go for the hammer treatment. :)

Hit each component with a hammer (of some type) while operating it, to see if something changes. (hitting a piece of pipe with a hammer that's taped to the eec while cranking it will tell you if it's that connector or box, lol.)

When it does change, you can narrow it down from there.

If you haven't unplugged, looked at, then replugged every connector in that circuit, you should do that first. :)
 

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Discussion Starter #4
I agree, this sounds like a reasonable answer. I went to try it out but its 35 degrees out so the car started lol. Its going to drop to 19 degrees today so ill try again tonight or in the morning tomorrow. Thanks guys. If anyone has any other ideas feel free to post.
 

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With success, I have replaced a few crank sensor connectors on 4.6l cars that would turn over but not spark.
 

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With success, I have replaced a few crank sensor connectors on 4.6l cars that would turn over but not spark.
I had one vehicle that would not start, two new crank sensors, same problem.

I would up having to run two new wires all the way from ECM to the sensor, then the vehicle started!

That's a rare occurrence - usually it's just the sensor is bad, not the wiring...
 

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Discussion Starter #7
Thank you all for your advice, after looking at the wiring diagram, it looks like the common connector is c161 (large rectangle connector in the engine bay -rear passenger's side). So today with a high of 27 degrees I went to start the car. Like always when its that cold it didn't start. I disconnected the connector and found excessive dielectric grease. I wiped the connector down and took a blow dryer to it for a few minutes. After reconnecting and bolting it down, the car started right up.

Hopefully this solved the problem.
 

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It wasn't the "excessive dielectric grease", but the wiping of the contacts due to the fretting.

Clean it out of the old stuff, sure, but you DO need to repack it or you'll refret.

Also, I'm a firm believer in treating with Stabilant-22A or DeoxIt Gold before reassembly also.

RwP
 

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Thank you all for your advice, after looking at the wiring diagram, it looks like the common connector is c161 (large rectangle connector in the engine bay -rear passenger's side). So today with a high of 27 degrees I went to start the car. Like always when its that cold it didn't start. I disconnected the connector and found excessive dielectric grease. I wiped the connector down and took a blow dryer to it for a few minutes. After reconnecting and bolting it down, the car started right up.

Hopefully this solved the problem.
Glad you may have very well found the problem.

And thanks for the update.
 

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...DeoxIt Gold before reassembly also.

RwP
Deoxit gold can be too aggressive for non-gold contacts, imho. :)

I'd look at the contacts, and see if there are "sprung" ones, or pins with corrosion on them. Replace any that look bad. Motorcraft even has a website, last I looked.

Spray all the old bad grease out with WD40 or equivalent; if it's hit water, it needs to go. (milky=water, clear=ok)

Refill the connector face after all repairs with new silicone dielectric grease, and stuff it together.

The grease won't separate the contacts unless they've lost their Mojo, and need replacing. :)
 
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