Massive hesitation, SES light flashing :(

[nimrod.sixty9]

Not sure why I have 1 - 4 twice...

 

[nimrod.sixty9]

Changed cap and rotor. Same result. Old cap did look bad though; looked to be arching to #4.

Tested wire resistance - Setting on 20k - All tested from 2.7 to 1.6; longest to shortest.

What's next?

 

[SunlitComet]

you don't see it twice you see to different counting pids. look at the history. something is wrong with 2and 4. if you have eliminated the dizzy cap as the issue you should do a compression/leakdown test of both of them to see if you broke the combustion seal between them. consider the minor counts on the other cylinders as stray or false positive from having so many on two or more cylinders. that is just the pcm seeing the the engine system reacting to the issues. Fix 2 and 4 and the others should disappear.

 

[nimrod.sixty9]

you don't see it twice you see to different counting pids. look at the history. something is wrong with 2and 4. if you have eliminated the dizzy cap as the issue you should do a compression/leakdown test of both of them to see if you broke the combustion seal between them. consider the minor counts on the other cylinders as stray or false positive from having so many on two or more cylinders. that is just the pcm seeing the the engine system reacting to the issues. Fix 2 and 4 and the others should disappear.

How do I tell which is which? Don't have the compression tool, Ill have to go rent it.

Do we really think that suddenly 2 and 4 is an issue, only a month after 3?

I never did the plugs on this side, so Im going to try that now. Then Ill be off to get the tool.

Anything else I should grab while at the auto parts? I ask this now because it's far away.

Thanks!

---------- Post added at 04:21 PM ---------- Previous post was at 04:18 PM ----------

Also, couldn't the history be from the previous misfire mishaps?

 

[SunlitComet]

compression tester has one gauge. leakdown has two with a more then one air line and a regulator. the history counts up as it happens hence the big number the current count was just the number between your data sampling rate basically. just shoot for the compression gauge for now and make sure the engine was heated prior to testing. if compression is low between them at the same time then likely you broke the cylinder seals. And I am sure you know what that means. And it happens, just have to push forward.

---------- Post added at 01:31 PM ---------- Previous post was at 01:31 PM ----------

I think of nothing else right meow.

 

[nimrod.sixty9]

compression tester has one gauge. leakdown has two with a more then one air line and a regulator. the history counts up as it happens hence the big number the current count was just the number between your data sampling rate basically. just shoot for the compression gauge for now and make sure the engine was heated prior to testing. if compression is low between them at the same time then likely you broke the cylinder seals. And I am sure you know what that means. And it happens, just have to push forward.

---------- Post added at 01:31 PM ---------- Previous post was at 01:31 PM ----------

I think of nothing else right meow.

I'll have to look up the process for the leak down.

I have just finished cleaning the air filter, installed new plugs, and cleaned MAF. It's a world of difference! Felt a bit of hesitation at first, but smoothed out pretty quickly. Haven't taken it for a test run yet.

Here are the plugs;

http://www.use.com/images/s_5/sorted/2013_10_06_255_3fa842606476af29b497.jpg

Both 2 and 4 smelled of fuel, with 4 having more. 8 was really dirty.

What do you think? One of the injectors dumping fuel?

 

[SunlitComet]

at this point I would try it with new plugs first on some runs to see if they help by not having a fouled plug in there. Test using a spark tester to ensure there is good solid spark using the existing cap and wire. Once you have eliminated those as the issue, instead of doing the compression check yourself, you might find it possible to find a shop to charge you a $100 diagnostic fee which should include a scan, injector balance test, ignition and compression test. At least that is what it cost most places here in the bay area in California.

 

[bowtieman55]

Do the AC Delco 41-993 plugs need to be gapped? Silly question I know, but I've never ran a platinum plug. I'm currently having the same P0300 code issue.

 

[bowtieman55]

I got the dreaded P0300 code yesterday after work. As soon as I started my Yukon, I noticed the idle was rough. It was slightly stumbling at idle in gear and had a large loss of power when accelerating; it sounded as if it was running on 5 or MAYBE 6 cylinders. SES light came on then started flashing. The it went solid and starting flashing again.
I made it home and immediately pulled and changed out the fuel filter...wasn't necessary. I then checked the fuel pressure. It checked out. This afternoon I tested the TPS, which also checked out. I pulled the plugs but didn't have time to pull the distributor cap yet. The plugs, cap, and MSD wires were installed 9,000 miles ago.

 

[SunlitComet]

the plugs are pre-gapped at .060". #2 looks wet with something, perhaps you know with what? #5 looks real dirty on a part of the insulator or it is cracked. can't see clearly. #4 looks to have a crack on outer insulator as well. #1 is just F*****. Next course of action is to finish your inspection but regardless replace your spark plugs with delco 41-993 or autolite xp605, also pre-gapped. Cap should be delco or delphi unless modding the ignition output.