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5.4L 3 valve low compression

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Mekanik

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I'm working on a 2005 f150 with a 5.4l 3 valve that has dtcs p0022, p0171, p0305, p0316. It seems to run pretty good, but when I did a relative compression test, cyl#5 is 10%low. I don't have a adapter to check compression. I'm borrowing one from a friend tonight. What have you guys seen other than bent rods from leaking injectors?

I have seen a couple that had bent rods from a leaking injector that caused the engine to hydrolock. I even saw one that had a bent rod that was hitting the block.

I'll probably have a better idea of what is wrong tomorrow.

I should also mention that I think it has a noisy camshaft phaser that lasts for about a second or two intermitently after starting. Has anyone ever dealt with the p0022 before? The pinpoint test is basically like" Clear the code and if it dosen't come back then go to Z1. "

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I'd just drop the pan and go right there. Every time I have an '05 3-valve with a previous injector history and a return misfire on the same cylinder, I do a relative compression test and if the results are "iffy" I take the pan right off. *EVERY* one has had a bent rod.

 

The pan seriously comes off in 15 minutes, it's cake. Get that front "crossmember" thing out of the way and then unbolt the motor mounts and both sway bar mounts, let the sway bar hang there. Jack up the front of the engine and the pan slides right out.

 

And short blocks are *JUICE* on these things too, the body comes off in 45 minutes and you don't even have to open the doors. Get the converter nuts and starter bolts out with a 3/8 impact and an extension/swivel combo once the heads are off, and yank the short block after tearing the engine down. I've had a couple that were in-and-out in well under a day and they paid out like 22-23 hours.

 

Dave

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Did one last week with a burned up piston. Melted right down to the 1st compression ring.

 

 

+1 on the bent rod thing, however, done one myself and have seen one other one.

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I had one that was a bad valve seat on #5,lower compression,did a leak down test and got air out the exhaust,but if the injector or injectors are leaking could have a bent rod,your start up noise could be the timming chain tensioners,I think the phasers are locked till it it hits a set oil temp?

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Well here is the update. I had low compression on cylinder #5 when I would first start the truck because it had a bad cam phaser. The first time I cranked the engine over when I was doing the compression test I only had 110psi. and the engine was making a knocking noise. I thought WTF, and then tried it agian... No knocking noise and my compression was now 210 on cyl#5. I actually took the valve cover off and watched the cam phaser. That whole bank had retarded cam timing when this would happen.

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