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2007 f150 catalytic converter issue
12-14-2015, 12:41 AM
Post: #21
RE: 2007 f150 catalytic converter issue
The plot thickens! Maybe it's my 2 weeks of vacation or something else but if you had said (if I remembered?) something about that high mileage I am sure we would have suggested a set of plugs right off the bat. They're really not that hard to change unless one is stuck in the head. (and I hear it's common) It probably wont set a code unless the misfire lasts for at least 5 - 10 seconds so maybe you haven't pushed it hard enough for long enough to set that code?
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12-25-2015, 02:59 AM
Post: #22
RE: 2007 f150 catalytic converter issue
Getting set to change out the plugs. I went ahead and ordered the Lisle "triton broken spark plug tool set". From the research I've done and from speaking with a couple mechanics, everyone says don't even attempt it unless you have the tool...be prepared for the majority of them to break. The tool should arrive in a couple days.

In my mind I've ruled out the cats as the issue. The P0420 and P0430 codes will come and go, haven't had the P0430 in two weeks. After drilling the holes in exhaust and the truck not driving any better, I don't believe there is any restriction. The fuel pressure is stable, intake air seems good. My experience with coil packs tells me that once they start acting up they go downhill fast and set off a code pretty quick, so I don't think it's a coil. Don't see how it could be anything else besides the plugs.

Motorcraft still makes the two piece plugs that break so we are going with the Champion as they are a solid one piece plug, albeit a $20 plug instead of $13 for the motorcraft! Between the plugs and the tool we have a $260 spark plug change! Needless to say, for that kind of money I wish I was 100% sure they are at fault. But, I don't know what else it could be, so we're going to go for it
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12-25-2015, 11:55 AM
Post: #23
RE: 2007 f150 catalytic converter issue
I found http://www.RockAuto.com has these for quite a bit cheaper. I see Autolite platnum listed for$7 and Champion double platnum for around $12. They also have the Dorman rethread tool (with an extra plug) for $36.

Good luck and Merry Christmas.
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12-25-2015, 12:33 PM
Post: #24
RE: 2007 f150 catalytic converter issue
thanks Rupe...already got the Lisle tool. It is one piece that pushes the broken porcelain down into the stainless "shaft" allowing room to get a bite on it. Then the other piece has left hand threads that grip the bottom half of the plug and turn it out. Along the lines of an "easy out".

Will let you know how everything works out. Have a merry Christmas and talk to you soon!
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01-10-2016, 11:57 PM
Post: #25
RE: 2007 f150 catalytic converter issue
We finally got time to change out the plugs. I really dreaded it after all the reading and talking to people about the extra long, two piece plugs and how they stick in the heads and then twist in half. Everything went pretty well though.

I started by giving each plug a quarter turn and then soaking with liberal amounts of P-B Blaster. After each plug soaked for about an hour I started taking them out with a 20v impact driver. It was slow going because the extra 2 inches past the threads gets so covered with carbon but the impact really worked well. Couldn't get the impact to turn the #4 plug at all, so had to do that one by hand and I'm amazed that it never broke. I would get it to turn maybe a half, listening to it pop and screech, then I'd have to let it soak again for a while before getting it to turn a little more. Probably spent an hour on that one plug before it finally came out, and it never did break! Got all 8 out in one piece!

She's been driving the truck now for two days since the plug change and it has not missed/stuttered one time, seems to have more pep now as well. Going to give it another day or two in order to make sure, but it seems like that issue is finally solved.

Probably should have changed plugs in the beginning... and if they were normal $2 plugs I would have. But with the cost involved and having to get the expensive broke plug removal tool for insurance on the assumption that at least a few would break, I was really hesitant to spend the money without knowing 100% that the plugs were indeed the issue.

Cleared the codes, but after about 10 miles the po420 and po430 codes came back. So I'd say it may indeed have some wore out converters, but I believe that is just in regards to their ability to convert the gasses, I believe the missing and stuttering under load was all in the plugs.
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01-11-2016, 12:51 AM
Post: #26
RE: 2007 f150 catalytic converter issue
A miss or other running issue can play hell with converters over time but I' glad the first problem seems to be solved.

Short story time: Been chasing a poor running situation with a high mileage Chevy Astro Van recently and when it hobbled into the shop with an arm's length of codes my first thought was to check the records. At near 200k I figured the first thing was to put a tune up into it. The file showed over 80k since a set of plugs and it was near 30k since a fuel filter. I went through the motions and installed the new parts. It still wasn't right and came back with a miss on #3 so I did a quick plug wire swap and still no change. Hey, I was tired and a van is a royal pain to do this kind of stuff on so I was shooting from the hip. At that point I figured it was on the lift and the tire was off so might as well pull the plugs on one side (again) and do a compression test. (it's a van and that's how you do it) I was looking to compare the good with the bad so I didn't need to do them all.

Compression showed about right but my clue was the compression tester hose came out of #3 full of gas, which kinda took me by suprise. The old plugs didn't show fouled but they were all equally a bit dark. Good thing I was still in diagnosis mode when it finally hit me that the injectors were leaking by! I added a new set of injectors and the thing is now cherry!

Lesson learned? Hard to say if anything new was learned here but certainly many old things reinforced. The age of the tune up was nearing it's end so not totally wasted parts / labor wise. I did change the OEM ignition coil, which is a 50/50 item by that age so again, not a total waste to clear a P0300 code. (multiple mis) I did go back and do an old fashion compression test even though I knew that really wasn't the problem, but it did lead me to my final fix. When in doubt cover the basics first. It really is part of the overall diagnosis.
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01-12-2016, 12:14 AM
Post: #27
RE: 2007 f150 catalytic converter issue
Another day past and its still running good with no misses. So I'm feeling pretty good. Wanted to touch on the vacuum testing again for a moment though.

I'm still just a bit confused about how the vacuum should read. So it's normal for vac to drop out to zero upon acceleration? And if it does not, then it's indicative of a restriction?

I've read a lot of guides to reading a vacuum gauge and they all describe different scenarios of what the needle does and what it means. I'm getting the impression though that the vac gauge can be a good tool for pointing in a viable direction, but not necessarily being a 100% accurate diagnosis? (unless your looking for a leak) Would probably be a good idea to hook it up sometimes and go for a ride when the vehicle is running fine just to get an idea what "normal" is for a particular vehicle. Then you have a reference point if you have to hook it up sometime later if you have an issue?
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01-12-2016, 12:31 AM
Post: #28
RE: 2007 f150 catalytic converter issue
You hit that nail square on the head. It's a great tool but "normal" is an individual sort of thing just like "normal" people is not the same to everyone if you follow my drift.

Still in all, the general rule of thumb has always been that low vac readings are a sign of trouble in retarded timing or vac leaks. A fluttering needle is most likely a valve issue (leaking due to burnt valve or broken spring, cam lobe wear, or uneven compression) although a really slow idle speed can throw you a curve ball. Vac should also drop to near zero at more than half throttle and continue downward as you gain speed, althoug you may see it level off at some point. "Perfect" vac at idle is near 20 inches but with cam profiles changing and emissions these days more typically we see 17 - 18 inches as pretty good if it's steady. A vac reading that will not hit zero and starts to build up slowly with sluggish engine response is likely a restricted exhaust. This is where that exhaust back pressure reading comes in handy.

Soooo, to recap: It's always a good idea to know what normal is so you have something to compare when the chips are down.
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