How do I troubleshoot a bad COP?

[krewat]

Originally Posted by Stone Mathews

Any advice on where to buy my COPs? What brand to stear clear of? Is this a strickly OEM part?

If this is a cat problem, is this a replacable part? Or is it time to put a piece of rebar to it? (I'm semi-serious here. They don't check much beyond seat belts on inspections around here, and I only put ~3,000 miles a year on my truck.)

You can bet I will be sharing my findings with you guys as soon as I figure it out.

We've had a few people buy aftermarket, cheapo eBay, OEM Ford, Accel, and others, and besides the early Accel's going bad quick, no one has reported a major problem with any of them. But that might just mean they never reported it either

The cat is replaceable, either OEM (probably expensive) or aftermarket. Do you have an O2 sensor AFTER the cat? If not, you can do almost anything and it won't light the CEL/SES or effect anything else in any way. Environmentally, and LEGALLY, it's an issue if you get pulled over by a zealous state trooper. And, for inspections, do they do a sniffer test, or just safety?

As to lighting the CEL/SES for a misfire, some people have had a solid misfire on one cylinder and NEVER gotten a code nor a light on the >8500 GVWR trucks from pre-'04/05. I take it that "higher threshold" in that document I posted means infinity

[redford]

You can buy a Ford converter. I had a Midas shop install a universal converter.

[redford]

Bear River Converters - Wholesale distributors of catalytic converters

You can get them from this site sponsor also.

[Stone Mathews]

First let me say thanks again to you guys hanging in there with me and my endless questions.

At this point it's time for me to do my homework and get back to you, so this post may go quiet for a while until I can get the time to work on my truck. No, they do not do anything beyond safety checks during inspections where I live. My backfirin', smokin', catalytic converterless, beater 1986 F-150 passed inspections here for the past 22 years, so I figure I'm safe. (So long as I don't move that is....) And no, my O2 sensor is before the cat, not downstream of it. (I feel like I should at least mention that I do not think it is a good idea to mess with the emissions equipment on any vehicle. I only justify it in that I put ~3,000 miles/year on my truck, actually only 1,200 last year, and 1,300 the year before......but then again, I'm not saying it's right.)

I'll report back as soon as I have some new data.

Thanks!

Stone

[redford]

I won't say to replace your cat, that's your call.

Let us know what you find.

Stu

[Stone Mathews]

Alright fellas,

I finally got a chance to look at my cat. I was able to break the flange upstream of the cat and drop it low enough to have a look into it with a flash light. The upstream face looks good and clean, but that is as far as I can see. Without pulling it all the way off and putting a light up through the bottom of it that is. The tight honeycomb doesn't let the flash light penetrate very deeply and I can't see very far into the holes.

So, my question is, based on everyone's experience, does a cat clog up at the upstream face, or does it clog up somewhere in the middle? (In other words, did I learn anything from just looking at the upstream face?)

Stone

[krewat]

I think they usually melt at the front, if it's a too-rich condition that caused it to overheat.

But from regular use, I think they just clog up over time.

The thing is, drive it with it disconnected and see what it does

[redford]

Whar Art said. Don't look at it, disconnect it and drive it.

[Stone Mathews]

Oh, I did. Melted the rubberized coating on my frame, and deformed my rubber hanger....lol!!!

It was rather hard to notice due to the exceptional noise, being that the problem is somewhat subtle. However, it did seem to have a LOT more guts. I hope that wasn't in my head, but it did really seem to move without that cat.

At this point based on Art's plugging comment, and the fact it did seem 'let loose' without it, I figure I'll pull it....

Thanks again guys, I will report back after I've driven it a few times post-replacement and let you know.

Stone

[krewat]

Originally Posted by Stone Mathews

Thanks again guys, I will report back after I've driven it a few times post-replacement and let you know.

Stone

Can you get a piece of 3" patch-pipe and remove the cat and drive it for a few days?

A new cat is nothing to sneeze at, money wise, I'd hate to have you buy a cat and it not fix it.

[Stone Mathews]

Amen art, cat is mucho denero.

Ok, I pieced together enought connections and patch-pipe to run it around a couple days now. I've concluded that the catalytic converter is NOT my problem. This of course does not rule out the muffler as creating back pressure, but it looks to be in good shape, and since my cat was sound, I have no reason to suspect it is plugged.

HOWEVER......while driving around and keeping an eagle eye on my truck, I did notice something I had not noticed before. When it does its "thing", the RPMs drop ever so slightly (100-300 RPM). It happens in between gears (normally 3rd gear) and is really only noticable when I'm really pouring the coal to it. When ever "it" goes away, I have an equal, if not slightly greater jump in RPMS like something kicked my truck in the arse. Sometimes during steady slower acceleration it will manifest itself as a stop in RPM climb, then the kick in the seat.

Any ideares?

Stone

[krewat]

Ooh... sounds like torque convert lockup clutch slipping...

When it shifts into 3rd, and then it sits, and then the RPM's drop, you get a vibration?

And then when it shifts into 4th (OD), and then sits a few seconds, and the RPMs drop again, does it vibrate?

[Stone Mathews]

No sir, no vibration at all. Gear changes seem very smooth. This only occurs in 'mid gear' and not at the beginning or the end. The only thing (remember my very limited knowledge about anything and everything) that would tie it to the transimision (in my mind) is that it seems to happen more often in 3rd gear and between 2-3500 RPMS and when under load as in towing a boat and/or accelerating up a ~steep interstate on ramp. I 'believe' I notice it above 3,500 RPM as well, but it isn't as pronounced.

Puzzling huh?

Stone

[Stone Mathews]

Rereading my posts, I see now better why you asked your question Art.

I said "between gears" and I should have said "between gear changes". I am solidily in 3rd gear, and climbing through the RPMs when the pause/drop in RPMs occur, NOT during a gear change.

Am I being any more clear? It's not during or even immediately before or after a gear shift, but actually "in" a gear's RPM range.

Stone

[krewat]

The torque converter lockup is a few seconds after the shift. It can be felt, and seen, as an RPM drop as it locks up. This can be a few seconds, or even longer.

If you can tell when the lockup occurs, and then this happens much later, it would help eliminate the possibility.

Clearer? Clear? As Mud? I'm going to bed now