Cylinder contribution test

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Mar 17, 2024 | 07:39 PM

Jamon Norton

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Cylinder contribution test

I’ve been chasing down a vibration in my 1999 that I thought was driveline related last week. I took it back to the driveline shop that did the rear end transmission and driveshaft. After driving it the mechanic said hey buddy I think you’ve got a miss in a cylinder so I ran a cylinder contribution test using for scan. I’ve ran it three different times and every time it comes back different first time it said cinder one, five and eight. Second time it said cylinder 2,3 and eight. I just ran it and it came back cylinder 1,2and eight. In the middle of this old mess I have added a lot more injector cleaner than I normally run and it seem to smooth out some. I also change the cam sensor. It had some aftermarket brand in it. I changed it to a Ford Motorcraft this also seemed to smooth it out even more. The only other code I’ve gotten is for exhaust pressure valve. I am assuming they are talking about the exhaust pressure sensor. I have kind of been thinking that this is becoming an issue because I have in the last couple months lost about 2 miles to gallon or three. Not really wanting to pull injectors and have them sent in yet for this slight miss didn’t know if anybody had had similar issues then Swamps remanufactured with about 90,000 miles on them. Truck passes a buzz Test

Mar 17, 2024 | 07:40 PM

Jamon Norton

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Also, would like to add that the truck has close to 400,000 miles on it but uses no oil and does not have any blow by per the oil filler cap test

Mar 17, 2024 | 08:00 PM

Tpayne621

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#3 will fail probably 75% of the time and 8 will fail about 99% of the time on a perfectly good running truck.

Mar 17, 2024 | 08:05 PM

Jamon Norton

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Quote:

Originally Posted by Tpayne621

#3 will fail probably 75% of the time and 8 will fail about 99% of the time on a perfectly good running truck.

could the exhaust back pressure sensor cause it to run a little ruff …. I’m assuming that is what FORScan cause the exhaust pressure valve

Mar 18, 2024 | 02:26 AM

aawlberninf350

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From: Elk Grove, CA

I don't think the exhaust back pressure sensor is a factor here. But exactly what code did you get?

Change oil recently? Synthetic helps old injectors run nice.

Mar 18, 2024 | 05:03 AM

Jamon Norton

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Quote:

Originally Posted by aawlberninf350

I don't think the exhaust back pressure sensor is a factor here. But exactly what code did you get?

Change oil recently? Synthetic helps old injectors run nice.

injector have 90k on them and yes it has fresh 15w40 semi synthetic

Mar 18, 2024 | 12:19 PM

udsuth78

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From: Ponca City, OK

There is an exhaust back pressure valve also. Most people disconnect or delete it which will throw a soft code without some sort of fooler plugged in. Have you tried any Hotshots or 2 stroke oil? Some people swear by the hotshots I don't have much experience personally. The 2 stroke oil added to the fuel ups the lubrication of the fuel gets it a little closer to the fuel the injector was designed to use, back before the ice started melting and polar bears were evicted. An ounce per gallon is the mix ratio if you want to give it a try, and just plain Walmart brand 2 stroke oil is what's recommended.