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3.0 misfire cylinder 1 at idle when warmed up


Lovemy98ranger

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Newbie here. I have. 98 ranger 3.0, now has 46k miles. Purchased last year with 11 k original from a mailman that drove it 2 miles a day to work and back, never left his town. At around 38k, I started noticing a skip here and there. Just got worse as time passed. Now it'll skip when idling after and only once its warmed up. Only code I pull is the cylinder 1 misfire. I've changed the wires, plugs, coil, iac, cps, cleaned throttle body, maf, changed fuel filter, pcv valve, egr valve, and injector #1. And a bunch of vacuum lines like the 4x4 to the hubs, the brake booster line with elbow and grommet, both intake lines ect. I also did a compression test, first time I think it wasn't tight enough and I got 90 psi on cranking cyl 1, then noticed it was loose, tightened then got 120-125 psi, and did this a half a dozen times, each at the same 120 reading. I noticed some of the other cylinders were at 150 psi. I'm stumped, this is my work truck, can't live without the 4x4,ive never pulled or loaded anything over 700-800lbs in it. Any help would be much appreciated. I'd hate to sell it, cause I love it. And just installed a fisher homesteader a couple
Thousand miles before it started the misfire.
 
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RonD

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Welcome to TRS :)

That 2mi to work and back is not a good thing, just FYI
Means the engine never fully warmed up which causes it to get gummy build up inside, but thats not your problem


Yes the compression is the issue
Static compression, cranking engine not running, is much higher than in a running engine
Which is why you get the misfire when engine is running and warmed up, compression on #1 is probably dropping to under 70psi

I would pull out ALL the spark plugs first and then test each cylinder again, with no spark plugs you should see 160-170psi from most cylinders because cranking speed is higher

Then do a WET test on #1, add teaspoon of oil to that cylinder and retest, MUST DO DRY TEST FIRST, then do wet test
Compression will come up but by how much will tell you if its a piston ring issue or a valve issue

If #1 dry test was 120psi now and wet is under 140 then valves are the issue

If its valves, which is 99% more likely than rings, then you can pull valve cover on that side and check the rockers, push rods and lifters for #1

Then go from there, which is pulling both heads
 
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Lovemy98ranger

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Thanks Ron. Kinda strange that it had 38k when it started acting up. Is this a bad designed engine or did ford use inferior Chinese metals when they made those heads/ valves/ seats ect. . Do the valvecovers have actuall gaskets (rubber, cork ect..) or is it rtv stuff from a tube?
 

JeremyS

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I just had this same issue on my 2002 Ranger with 145k miles. The cylinder had low compression on both a dry and wet compression test.

The only fix was to install two rebuilt heads. It was a lot of work but I did the job in two days in my garage.
 

jscraiderfan

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This was my problem when I first bought my truck, only mine was Cylinder #6. I heard something about an issue Ford had with the valve seats on these engines and indeed all my exhaust valve seats were bad, even had 1 Intake valve seat starting to go. Two reman heads later good as new. I'm kinda surprised this would be your issue with that low of mileage but I guess anything is possible.. Its not a hard fix if thats the case just tedious.

Lovemy98ranger said:
Do the valvecovers have actuall gaskets (rubber, cork ect..) or is it rtv stuff from a tube?
Valve Cover Gaskets should be rubber (at least mine were), they use a dab of RTV where the gasket goes over where the heads meet the Intake Manifold, but other then that no sealant needed. If do replace the heads just get the Felpro Upper Engine Gasket set (not sure the part # off hand) it'll have everything you need.
 
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Lovemy98ranger

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98 3.0 heads

Thanks. I did remove the cover to check for any signs of failure. The only thing that I could see( actually feel) was, I removed the pushrod and rocker from the bad cylinder exhaust valve (#1 misfire) I used a pair of vise grips and gently locked onto the valve stem, and gave it a few spins, I did the same thing
to the intake valve, and notice the intake valve spun evenly or seemed to spin smoothly, but it was tight. When I did that to the exhaust valve, it almost seemed like it was dragging, and it took more pressure to spin it, seemed as if it wasn't as smooth spinning as the intake valve was. Does anyone have a recommendation on where to buy some quality heads (that I won't have to replace again in another 30-50k miles). Something that won't
Break the bank. And does anyone know if all these reman heads use the original problematic valve seats, or do they rebuild these with better valve seats now? amy info would be greatly appreciated as I am going to replace to heads within the next week or 2
 

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Thanks Ron. Kinda strange that it had 38k when it started acting up. Is this a bad designed engine or did ford use inferior Chinese metals when they made those heads/ valves/ seats ect. . Do the valvecovers have actuall gaskets (rubber, cork ect..) or is it rtv stuff from a tube?
There are known issues wit h burnt exhaust valves on the 3.0. Having only 38k has nothing to do with it. Older vehicles with low mileage are generally nightmares. An engine that was driven 2 miles a day for 20 years is gonna have the crap kicked out of more than an engine with 150k.
 

JeremyS

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I purchased two rebuilt heads from the Cylinder Head Shop in West Virginia per a recommendation that I saw on here. They seem to be good quality, were professionally packed, and I had good even compression across all cylinders after installing them.

To replace the heads on my truck I spent around $600. That includes two sets of FelPro head bolts, a Fel Pro head gasket set, a couple gallons of Motorcraft Gold Antifreeze, and a few misc shop materials. I also replaced my cam syncho and position sensor (using Motorcraft replacements) while i had the engine apart.
 

Fordblue213

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I had to do heads and head gaskets on mine at 180,000 miles:

 

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