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  #1  
Old 01-16-2013, 06:39 AM
okcutiger okcutiger is offline
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Default 3.0L compression

2000 3.0L flex fuel. Misfire on 6. New plugs and wires. Checked compression and 6 was at 90 compared to 130 on the others. Ran seafoam through intake and rechecked compression and it was back up to 120. Ran seafoam again. Still getting a misfire. At what compression should it fire. I feel it is back in tolerance with compression, why am I still getting misfire?
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  #2  
Old 01-16-2013, 09:52 PM
mopar9012 mopar9012 is offline
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Default Re: 3.0L compression

What kind of plugs did you use?

Only use autolite or motorcraft plugs. Dont get the double plat crap....
It matters.
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  #3  
Old 01-16-2013, 11:39 PM
LargeR LargeR is offline
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Default Re: 3.0L compression

I use NGK plugs in my 3.0 and have never had a mis problem; so that whole "only" autolite or mc is not necessarily a factor. If you think it's spark related, check your coil pack. Remember though to have combustion you need more than just spark. A bad injector could also cause a problem. Heck, just about anything could be the culprit from the MAF to the PCM. The computer detects misfires with the CPS. Usually an unstable RPM is read by the PCM and depending on what position the crank sensor indicates the motor drops RPM at is how it determines where the mis is located. How did the OLD plugs look? Were they worn out of spec? Your compression testing results are concerning; have you performed a cyl leak down test? Wet comp test?
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  #4  
Old 01-17-2013, 04:49 AM
mopar9012 mopar9012 is offline
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Default Re: 3.0L compression

From my experience and a lot of guys on this forums experience it does matter. Maybe not always a misfire right off the bat but it could cause problems down the road. I've never been able to use anything but autolites or motorcraft.
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  #5  
Old 01-18-2013, 07:33 AM
okcutiger okcutiger is offline
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Default Re: 3.0L compression

I put in autolite plugs. My theory is that a plug or wire went out and it has been running like this for a bit and built up carbon in the head. Seafoam cleaned a lot of it out and the compression came back up. My plan now is to run seafoam again to see if it still has any remaining carbon and check the compression again. I also plan to check the injector to see if it is firing. If everything is looking good then maybe replace the coil pack. I also suspect the camshaft position sensor. I talked with a mechanic and he said it should be firing with that compression. When I pulled the plugs to check compression after the seafoam, it looked to me like the spark plug in the cylinder with the miss had been firing. As far as the old plugs, as well as I remember they looked pretty good. The one that was in the cylinder with the miss was so loose that we just unscrewed it by hand.
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  #6  
Old 01-18-2013, 07:43 AM
Prages Prages is offline
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Default Re: 3.0L compression

Quote:
Originally Posted by okcutiger View Post
The one that was in the cylinder with the miss was so loose that we just unscrewed it by hand.
That would definitely cause a misfire.
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  #7  
Old 01-18-2013, 06:52 PM
LargeR LargeR is offline
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Default Re: 3.0L compression

Quote:
Originally Posted by mopar9012 View Post
From my experience and a lot of guys on this forums experience it does matter. Maybe not always a misfire right off the bat but it could cause problems down the road. I've never been able to use anything but autolites or motorcraft.
I never said plugs don't matter, I said "Only Autolite or MC" is not factor NGK makes a few fine plugs that works very well in our 3.0's. In my experience, autolite is just another plug and I've had them bad right out of the box. I've also seen MC plugs bad right out of the box. Alternatively, I've NEVER had a NGK bad out of the box and use/recommend them in every vehicle that comes through my shop if they make an applicable plug. Down the road? Like when the plug is worn out of spec? I've had 2 sets in my truck in over the last 140k miles and never thrown a misfire code (currently just under 200k on my truck now). I've installed at least hundreds of NGK in various vehicles and had exactly 0 come-backs for mis-fire, so "down the road" isn't a factor either. Yeah, I know I sound like I'm brand humping for NGK but they flat out work, every time, so that's why I prefer them. If you want to use AL or MC that's fine but your not limited to ONLY autolites or MC.

Quote:
Originally Posted by okcutiger View Post
I put in autolite plugs. My theory is that a plug or wire went out and it has been running like this for a bit and built up carbon in the head. Seafoam cleaned a lot of it out and the compression came back up. My plan now is to run seafoam again to see if it still has any remaining carbon and check the compression again. I also plan to check the injector to see if it is firing. If everything is looking good then maybe replace the coil pack. I also suspect the camshaft position sensor. I talked with a mechanic and he said it should be firing with that compression. When I pulled the plugs to check compression after the seafoam, it looked to me like the spark plug in the cylinder with the miss had been firing. As far as the old plugs, as well as I remember they looked pretty good. The one that was in the cylinder with the miss was so loose that we just unscrewed it by hand.
Can you hear/feel the mis? If it's been running long enough to cause the kind of carbon build-up you're talking about you should have a noticeable misfire. If you don't notice it, it may be an injector. Injector misfires are usually intermittent and sometimes harder to detect than a dead plug... If you have a wire arcing to ground, you can see those better at night. Check the new #6 wire didn't rub against the exhaust manifold and melt/short to ground. How quickly did the code return after you replaced plugs and cleared the code?
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'99 Ex-Ranger 2wd XLT 5.0, Explorer V8 and auto transmission swap, floor shifter from Nissan Altima Parts, aluminum radiator & electric fan, OBX headers, 3" custom exhaust, explorer roof rack, 2006 mirrors, cut front 60/40 seat to buckets, 4 in lift spindles up front and shackles in back
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  #8  
Old 01-23-2013, 09:08 AM
okcutiger okcutiger is offline
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Default Re: 3.0L compression

LargeR - Sorry for the delay in response, I have been beating my head against the steering wheel. I do not feel the miss at road speed. At idle I feel the vibration. At idle when I pull the plug wire off of #6 it does not make a difference. I changed the coil pack this weekend, no difference. It will run around 30 miles after clearing codes before it comes back on. I have spark from the coil pack through the plug wire. I pulled the plug this morning and it is not fouled and I could smell gas on it. I managed to get a scredriver on the injector and listen through it and I could here the injector "ticking". I plan on checking the idle control valve and see if it is clogged and clean it. My next steps are to check compression again, then hook the air compressor up to the compression hose and see if the valves are leaking. Really trying to avoid pulling the head.

I don't smell antifreeze, no evidence of leaks and I think if the head gasket were blown I would have other symptoms. No hesitation or bucking or shudder at road speed. Input is appreciated.
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  #9  
Old 01-29-2013, 11:49 AM
okcutiger okcutiger is offline
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Default Re: 3.0L compression

I know what the problem is now and i just need to fix it. Took it by a machine shop that had done work for me before. He put his hand over the tailpipe while it was running and it sucked his hand back into the pipe indicating a bad exhaust valve. I need to take the head off and have it repaired.
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  #10  
Old 01-29-2013, 05:32 PM
Bsenevey Bsenevey is offline
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Default Re: 3.0L compression

I am pretty sure I have the same problem. How difficult is it to get the head off and what cost are you look at for having the machine shop repair your head? The dealership quoted me a ridiculous price of 3,600 and then told me I might as well get a new motor for 4,200. Another shop told me a 1000. and then another told me to get a new motor.

Thanks,
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  #11  
Old 02-01-2013, 07:23 PM
okcutiger okcutiger is offline
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Default Re: 3.0L compression

Hey Brock - I am looking at around $100 for the machine shop to repair the valve. He repaired a bent valve on a VW Jetta head for me for $75. Gasket kit $129 (I think) and new head bolts for around $25. Started it today and I am down to the exhaust manifold and the head itself. The problem areas are removing the bolts from the combination a/c power steering pump bracket. There are 2 bolts that you can find only by feeling for them and you have to remove the fan and belt tensinor and idle pulley. My problem is on the drivers side on the other side I think you would have it a lot easier. My problem now is the exhaust manifold bolts. I can't get them to budge. Have them soaking now in penetrating oil. Will try tappining on them and see if they will loosen. For a shop to do it there is a lot of labor. I worked steady on it 5 hours and still have the manifold and head left to pull off. You need a good set of metirc sockets and patience. The shop manuals are not a lot of help, at least Chiltons. The say remove power steering pump bracket, they don't tell you about the inaccessibility of some of the bolts.
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  #12  
Old 08-09-2014, 05:04 PM
gspears gspears is offline
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Default Re: 3.0L compression

Quote:
Originally Posted by okcutiger View Post
Hey Brock - I am looking at around $100 for the machine shop to repair the valve. He repaired a bent valve on a VW Jetta head for me for $75. Gasket kit $129 (I think) and new head bolts for around $25. Started it today and I am down to the exhaust manifold and the head itself. The problem areas are removing the bolts from the combination a/c power steering pump bracket. There are 2 bolts that you can find only by feeling for them and you have to remove the fan and belt tensinor and idle pulley. My problem is on the drivers side on the other side I think you would have it a lot easier. My problem now is the exhaust manifold bolts. I can't get them to budge. Have them soaking now in penetrating oil. Will try tappining on them and see if they will loosen. For a shop to do it there is a lot of labor. I worked steady on it 5 hours and still have the manifold and head left to pull off. You need a good set of metirc sockets and patience. The shop manuals are not a lot of help, at least Chiltons. The say remove power steering pump bracket, they don't tell you about the inaccessibility of some of the bolts.
This is great info. Can you please let us know what happened? Give us details of what you ended up having to do and how it all turned out?

Thanks.
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  #13  
Old 08-09-2014, 05:30 PM
dfpgnm dfpgnm is offline
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Default Re: 3.0L compression

Various tools I've used to loosen frozen bolts: a hand held impact driver. Put a 6 point impact socket on it and hit the end with a hammer.

A propane torch.

An air impact driver. (even a air ratchet might do it)

The last thing you what to do is go with a long handle breaker (or pipe). You'll snap the bolts before you loosen them and that would be a major bummer. But then again, a machine shop should be able to drill and tap the holes while they have the head.

Can the shop do the valve with the manifold still attached?
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Last edited by dfpgnm; 08-09-2014 at 05:33 PM.
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  #14  
Old 08-09-2014, 08:44 PM
floridacracker floridacracker is offline
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Default

At work we have a lot of these problems with 3.0s but we finally figured out tht the ford 3.0 exhaust valves get gunned up with carbon so bad tht they dont fully close which causes a misfire feeling with no trouble codes so this may have been your issue
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  #15  
Old 08-09-2014, 09:30 PM
GLH GLH is offline
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Gummed up ? Is there a simple fix without engine disassembly ?
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