So, some of you saw that I had issues with misfires on the dyno by the end of my 8 hour roller session. Started out building the VE table on the single pump on 10psi. It wasn't until I started turning up the boost that I put the fuse in for the second pump. Loaded up on the rollers like that, the injectors were static for some time, and I think they may be damaged now.

I'm posting up a couple logs, miss4 is an idle log and miss5 is me driving. Seems to miss quite a bit on decel when IPW drops real low. And of course, it happens at WOT/high boost. Does this look like an injector fault? Happens on all cylinders

 

Need a config to look at your log.

Aside from that, one thing you can do is ohm test all of the injectors. You can also do an injector balance test if you have a scantool. I'd start there, then do a compression test.

 

I made the logs on my netbook, but my main PC opens them with the default imperial. Did default not work?

I ohmed out the injectors, all came back 14.4-14.5. A friend of mine made a comment that it runs too well otherwise to be messed up rings or something of that nature. I'm wondering if some crap got stuck in the injectors. I have a 100 micron fuel filter in the tank, but I wonder if some tiny stuff got through it and is distributed throughout the injectors now.

BTW, I have replaced all the plugs and I just tried another ECM to rule out a failing injector driver.

 

No, I didn't even try to open the files without a config file. I just did, and I was able to open them.

That's not a whole lot of misfires for a cammed engine with a converter, that's running way too rich. I'd still do a compression test, just for the sake of doing it. Then, if you're convinced that your ignition system is perfect, get the tune nailed. Don't go chasing ghosts until you do all of that.

That's just my opinion, and what I'd do.

 

It is a pretty mild cam, though. Unless its running lean you can't hear it. When it misses, its a dead miss. It feels like I am towing someone with a strap who doesn't know how to be towed and the strap is bouncing lol. At WOT its very exaggerated. I am thinking it might be that the second pump started puking out stuff when I turned it on. I cleaned everything out though, so I'm not sure. Would it miss like that if injectors were plugged?

 

Welp, went ahead and cleaned the injectors in an ultrasonic parts cleaner that a friend of mine had. There were tiny bits of debris in the injector filter, which I was happy to find because I figured it might solve the misfire problem. At idle it still missed and revving it in park still missed, but decel felt fine. Getting into boost a bit, I heard the weirdest sound from the passenger side. Engine is too hot now, but after it cools I am going to pull the valve cover and look for a broken spring

https://www.performancetrucks.net/fo...-today-482438/

This thread sounds a lot like the problem I have. Since I am running **** for timing right now, things probably got pretty hot on the dyno... ECT was stable but that doesn't mean the springs didn't get angry. Will update soon..

 

Seems that new coil packs fixed the misfire in boost, but it still misses at idle and under light load. Could this just be due to the colder plugs?

Also considering these as potential problems, even though there are no codes...

-O2 sensor(s) bad/going bad
-short in harness wiring
-ECT sensor bad/going bad


It ALWAYS happens when its deep into vacuum, like 15inHg or more. I'll be cruising in 4th, converter locked and like 15inHg vacuum, and it jerks back every couple seconds. Doesn't happen often enough to unlock the converter. Scanner shows misses on all cylinders intermittently, and WB O2 shows the tiny lean spike. So confused