When I went through school, we were taught that CELs blink when the fault can damage the catalytic converters.
0411 swap done, did crank relearn...now it doesn't run
- Thread starter gearheadE30
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gearheadE30
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Yeah, I have also heard that. Which, considering what a misfire is, makes a lot of sense to me. From what I can find, there is some threshold between a 'normal' P0300 misfire count and a 'blink the MIL lamp' misfire count. I'll have to see if I can find it in the tune file.
By the way, here is the burned brand new distributor cap. Zero evidence from the top.
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HotWheelsBurban
Gotta have 4 doors..... Rawhide, TOTY 2023!
Seems like to me,based on what I know and have read/heard, that if the rotor is getting burned like this, the coil might be bad. If it or the wires are original on a 98 truck, they could be worn out(or close enough to make a difference with the better computer). My 99 Burb 5.7 with 189 thou, probably needs wires and plugs (has just a wee bit of rough idle sometimes). Need to quit driving it so I can do these.....before it gets worse.
Christian Steffen
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IMO if you can't actually feel the misfire I'd just desensitize the misfire table. Its probably a little different on my truck with the cam being aftermarket, but when i 0411 swapped i had to desensitize the idle area.
gearheadE30
I'm Awesome
Well, the plug wires on my '98 and my Tahoe Limited look the same and look pretty old, so it would not surprise me if they were original. That means 262000 miles, so I went ahead and bought a set of wires. It can't hurt, I suppose.
@Christian Steffen the misfire is just enough that I can feel it a little at idle, the same as I can in the K1500. It is very slight. Definitely cannot feel it at all when driving, and if it weren't for the code and SES light, I wouldn't even be looking for a problem. So you are probably right that since it's running well, there is no reason to desensitize the table a bit. I need to educate myself on how that table and diagnostic work, but shouldn't be too bad to sort out. So far, I'm pretty happy with how easy EFILive is to use and how easy it is to iterate calibrations.
@Christian Steffen the misfire is just enough that I can feel it a little at idle, the same as I can in the K1500. It is very slight. Definitely cannot feel it at all when driving, and if it weren't for the code and SES light, I wouldn't even be looking for a problem. So you are probably right that since it's running well, there is no reason to desensitize the table a bit. I need to educate myself on how that table and diagnostic work, but shouldn't be too bad to sort out. So far, I'm pretty happy with how easy EFILive is to use and how easy it is to iterate calibrations.
That is interesting as I replaced a distributor recently, I had out of the blue a poor running truck and had the CEL come off and on and at highway speeds blink. So I replaced cap/rotor which improved it but CEL still came on at times. Replaced distributor all good, now a month later I get P0430 which I guess is 90% of the time a bad cat.
gearheadE30
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Well, I have some good news and some bad news.
Bad news first: replacing the plug wires did nothing measurable according to the datalogs.
Good news: retuning the misfire logic worked. I took a few datalogs driving around and found a couple key areas that were really driving up the counts, but in general the recorded counts were riding or slightly exceeding the limit everywhere. My goal was to make the limit match the actual count curve plus some buffer, and I think I was able to get pretty close. The worst case areas for my truck were light load between 1000 and 2500 rpm with a particularly nasty window between 1900 and 2200 that was causing the blinking SES. Once I figured that out, it was completely repeatable.
Just got back from driving around for a bit, specifically trying to drive in those problem areas. No issues at all so far. If I do have an issue, it will be caused by coast down misfires between 600-800 rpm, 20% load, VSS between 15 and 5 mph. It's all fine at steady state, but not pulling up to a stop for some reason. I'll move this area up in the cal a bit to be safe, and am calling the issue fixed.
After all this, I am very glad I bought EFILive instead of getting a mail order generic tune.
So, in review:
Bad news first: replacing the plug wires did nothing measurable according to the datalogs.
Good news: retuning the misfire logic worked. I took a few datalogs driving around and found a couple key areas that were really driving up the counts, but in general the recorded counts were riding or slightly exceeding the limit everywhere. My goal was to make the limit match the actual count curve plus some buffer, and I think I was able to get pretty close. The worst case areas for my truck were light load between 1000 and 2500 rpm with a particularly nasty window between 1900 and 2200 that was causing the blinking SES. Once I figured that out, it was completely repeatable.
Just got back from driving around for a bit, specifically trying to drive in those problem areas. No issues at all so far. If I do have an issue, it will be caused by coast down misfires between 600-800 rpm, 20% load, VSS between 15 and 5 mph. It's all fine at steady state, but not pulling up to a stop for some reason. I'll move this area up in the cal a bit to be safe, and am calling the issue fixed.
After all this, I am very glad I bought EFILive instead of getting a mail order generic tune.
So, in review:
- Original distributor had worn gear and bushings, marginal cap. Not enough adjustment to get CMPRET in spec.
- New distributor had a failed rotor, but CMPRET 0 degrees is right where it should be.
- Combine the old good rotor with the rest of the new good distributor and misfire count dropped dramatically, plus I could actually set timing.
- 0411 ECM diagnostic has tighter misfire limits and/or is faster and can actually sense them, where the black box didn't care. Retuning the misfire limits, especially at low load, takes care of it.
HotWheelsBurban
Gotta have 4 doors..... Rawhide, TOTY 2023!
Happy to hear that you are getting a handle on this! I would recommend a Blue Streak rotor. I'm very happy with the one I have on my Burb. I was only getting 6 months or so on the cheaper white rotors. The Blue Streak rotor has been working great for a year and a half now. Just because it's relatively easy to change, doesn't mean that I want to have lots of practice doing it LOL.
Just be sure you look at the rotor and the box it's in to be sure no one dropped or broke it!
Christian Steffen
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Good work! Having tuning software and the datalogging that goes with it really is invaluable.
Crazydavez28
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Since you did 0411 swap Check the injector bank assignments in your tune. Also LS firing order is different than SBC.
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