When I went through school, we were taught that CELs blink when the fault can damage the catalytic converters.
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When I went through school, we were taught that CELs blink when the fault can damage the catalytic converters.
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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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.When I went through school, we were taught that CELs blink when the fault can damage the catalytic converters.
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.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:
- 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.
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:
- 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.
Like the title says, I got my 0411 swap done on my 2000 Tahoe Limited and works great. I have EFILive and am not new to tuning, so it wasn't too big a deal. However, when I was going through the checks after getting it running, I discovered that CMPRET was about 38 degrees. I should have had a code off that far with the original ECM, but I didn't that I'm aware of.
I wasn't able to get the distributor clocked enough to bring that number down any further, so I checked and found some pictures online and it appears that the distributor was a tooth off. Set to cyl 1 TDC, pulled and reclocked the distributor, and now everything looks like it should. Reinstall, dial it in so CMPRET is between 0 and 3 degrees, and I figure I'm golden.
Except I'm not. Pending P0300 for tons of misfires, and TCC lockup shows disabled due to misfires. It also doesn't idle at all (instantly stalls after starting), which tells me that timing is off...but if CMPRET is 0, how can timing be off. It will run if I keep my foot on the gas.
What did I do wrong? Is there something else I missed in that procedure? I've never heard of setting the cam position retard causing new problems, and searching turned up nothing at all.