1998 5.7l V* Misfire

So guys n gals, my last post was about a P0300 code on my 98 Tahoe. Installed a new aftermarket distributor, (after a whole mess load of other part replacements) and it seemed to be fine.

Today I drove to the store, parked, went in, came out, started it up and it idled rough. I limped it home when the SES light came on. and then flashed, then stayed solid, then flashed again.

I plugged my Solus into it and read the obdII codes and i have a P0300 again. Only this time I check the misfire cycles and #2 and #8 cylinders are having problems.

I noticed my spark advance was at 21 degrees as well
engine rpm was 600 rpms at idle
Coolant was 170 F
MAF was 6.57 g/s
load was 3%
MAP 10 inHg
Closed loop on egr

this was a 4 minute run time for the test.

I will admit, I am not a professional tech, so i need help.

Any ideas why only #2 and #8 are problematic?

So is a stedy misfire? Did you check spark for does spark wires(2 and ?

Sorry...and nr 8 cylinder?

Yes, both have spark. The light was stronger on #8 than #2 but still good spark.

Did you check both spark plugs. If they are ok next you can check if injectors are ok!

Yes, both plugs are good. I was afraid of the injectors bc it's the spider system, and I don't know how to do it without removing them.

Can I use my snap in tool to do it?

I'm not familiar with American cars, but you have access to the injector plugs and you can see if there is power and control. You can make a inj. balance test and you can watch Paul Danner (ScannerDanner) videos about it!

Ok. Thanks.

I suspect you have a bad distributor cap.



as you can see in the image #2 and #8 run next to each other in the cap and a crack can form inside the cap causing a misfire .

Watch Paul demonstrate how to test to cap.

knowledge is a weapon (good one)!

I changed out the cap and she purrs like a flowmaster kitten! Thanks so much for your help, that cured my ail!!!!!!!

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