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Truck broken down, need ideas

I replaced both cats with new non-clogging types:
IMG_2558.jpg

It idles fine now and seems to run like it did last week. My plugs were all sooty, so I'm probably rich, but part of that could be from the one day of running awful, vs. a couple weeks of seeming to run well.
 
It ran pretty good for about a little while and then it started to get rough again. Maybe I am just fouling the plugs quickly. Number 7 is oily.

At least I got it home tonight.
 
I poked around tonight and found that I can unplug the #7 injector without affecting the idle. I think that spark plug is fouling out rather quickly. When I turn the engine off, the fuel pressure stays at 30psi for a long time, so I don't think that an injector is stuck open. I'm wondering if the engine vacuum sucks fuel through it though. I guess I have almost 10psi of vacuum. I'm thinking at this point that the #7 plug is not oily, but wet with gas.

There is carbon powder in the intake, even though it was all clean when I installed it a few weeks back. This must mean the EGR valve is operating. This kind of carbon I readily attribute to a rich engine. What I found in the exhaust was like coarse sand. The tube coming from the charcoal canister looks clean, though. At least the one from the throttle body. There is another one tied into the PCV circuit.

I am considering a new set of matched injectors.
 
The ford injectors (changed their name, used to be SVO) are supposedly extremely good values. Summit sells them.

That first carbon pic looks like gunpowder to me, it just seems to be too coarse to be carbon from running rich. Just a picture though, you've got hands on. :)

You can measure the injector resistance with a multimeter. It's not a tell-all, but they should be relatively close, I believe the GMN 350 injectors are anywhere from 13-16 ohms if good. I've got one down to 11, but it still seems to work. New injectors are in my future too, but I've got other issues to sort out before throwing that in the mix.
 
I actually have a set of SVO injectors on order, 24 lb/hr. All of the existing (Multec) ones are still about 12 Ohms. I'm not sure that one isn't squirting. It could be that the plug is so bad that it never fires.

As for the carbon, I was in total disbelief that an engine could make it, too. Now that you mention it, it did look like muzzleloading powder or black sand. I could crush it with my fingers and it looked like graphite. All I can figure is that the engine was making fine carbon powder and the cats were turning it into granules. Maybe these were just junk cats to begin with and I pushed my luck with "safe" mixtures during tuning.

I forgot to mention: when it is running now, it smells really weird. It doesn't smell like raw gas, oil burning or coolant burning. It's something new to me.

I've been working long hours and haven't had much time to tear into it more.
 
Since the catalyst is somehow bonded to the honeycomb matrix, wonder if that separated? Too hot perhaps?
 
dyeager535 said:
Since the catalyst is somehow bonded to the honeycomb matrix, wonder if that separated? Too hot perhaps?
Click to expand...
I've been struggling with that. If it got too hot, wasn't it lean? If it made carbon, wasn't it rich? When I was working on it, I had the impression that the headers were giving off more heat than when I had the carb on. This indicates lean, but I don't have any real numbers to back it up and I probably never spent so much time underhood with it idling before. It never tried to overheat or anything and I checked out the cats a few times after driving and they didn't seem unusually hot to me.:dunno:.

My current pet theory is that the injector on the suspect cylinder is really slow, either opening or closing. When I have decent pulse widths, this would be less noticeable, which is why acceleration was fine. At idle, however, the pulse-width is like 2.2ms, but the opening time is about 1.0ms, so the actual injection time is only 1.2 to maybe 2 ms. If the opening/closing time changes much, then the mixture in that cylinder is all wrong. Once it carbons up, the plug won't fire right and it is dead.

We'll see how it works with new injectors and a rebuilt throttle body.
 
I saw an article with 8 wide bands, one for each cylinder. THAT I'd love to have. :)

Also like to have at least one on each cylinder bank that could be seen in operation.

I'm just used to engines that are running poorly and generating a bunch of carbon having the flaky stuff that clings to the exhaust pipe. With cats that could probably end up different. Just very odd looking stuff.
 
I would like 8 WBs, but it would be even better if all 8 injectors were controlled seperately, but for troubleshooting that would be awesome. What I really DREAM of is electronic valve actuation, but let's get back to the real world...

I did some simple tests on each of the injectors and #4 seems partially plugged. I swapped in the SVO injectors, so that is not an issue anymore.

Now here's the scary part. I found that some of the junk coming out of my engine is affected by a magnet. I haven't concluded yet what this means.
 
So did you get material that was coming out "pre-cat" before you put it all back together, but after taking the cats off and hopefully blowing any remaining junk out?

If you did, I'd certainly be looking at a leakdown/compression test for each cylinder, you can't get metal into the exhaust without it coming from upstream somewhere :( Could be something else going on with that suspect cylinder.
 
dyeager535 said:
If you did, I'd certainly be looking at a leakdown/compression test for each cylinder,
Click to expand...

I guess we're thinking along the same lines. Here are my compression results:
#1 150
#3 153
#5 153
#7 153
#2 150
#4 151
#6 144
#8 150

This looked good enough that I didn't piece the leakdown tester back together. I cleaned the plugs up while I had them out. Then when it was all back together I started it up. With a little tuning I had the best idle I've seen since the carb came off. The vacuum was up to about 21", which is what I used to get with the Q-Jet.

Everything looked good enough that I went for an unplanned drive. It ran great. Without even tweaking any fuel settings it was pulling really strong. It also didn't try to ping at 3000rpm. I attribute all of this good news to the new SVO blue-top injectors. I started "steam cleaning" by spraying some water in the intake. I might get some top engine cleaner, though.

So where did the black stuff come from and why is it metallic? Is my engine doomed or are my troubles behind me?
 
Blue85 said:
So where did the black stuff come from and why is it metallic? Is my engine doomed or are my troubles behind me?
Click to expand...

When you pulled the cats out, did you inspect forward of them to see if there was junk ahead of them too?
 
Most of the stuff I found was right in front of the cats. The smaller particles were going through or getting caught in the cats and the larger ones were accumulating there. The particles are not metal, but some of them do have some metallic content.

I drove again yesterday and it runs well.
 
Update! The carbon was from my charcoal canister!

Everything has been fine with my setup until this weekend. I made a throttle bypass valve to increase the idle air when the A/C compressor turns on. In the process I reconnected the charcoal canister, since it shares a throttle body port with my new air bypass setup. It worked at first, but then it seemed to have no effect on idle speed anymore. I started pulling hoses apart to check for vacuum and one of the Tees was full of little granules. This was the Tee connecting the canister to the vacuum source.

So yes, some of the old injectors were dirty and of course this didn't help things, but the cats were plugged with the contents of the charcoal canister, not carbon buildup from an overly rich mixture.
 
Dunno how you'd ever have figured that one out lol.

Nice to see you got it fixed, next time someone shows a pic of a bunch of fine carbon, we know what to check. :)
 
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