Ran the noid a few times. No issues.

Per GM:
http://pafirefighter11.smugmug.com/p...kjpLGwC-XL.jpg

did you start the car withthe cover off to confirm it wasnt mechanical. have you swapped the whole coil bracket?

Have you tried swapping the ignition wires around?

There is spark per GM. I swapped in an LQ4 row of coils and that didn't change anything. It's not the coils or those wires. I did not start the car with the valve cover off. I didn't know to do that. I'm definitely not a mechanic lol.

I am going to swap in the Crank Position Sensor from my '01 to see if that changes anything. My buddy had his go bad on a few vehicles and it causes similar issues.

So the actual ignition wires have been moved to different cylinders or completely replaced?

not sure if feasible... but could you program the ecm firing over such that 5&7 become 1&3? THEN switch the plug wires and injector connectors so that actual firing order is correct?... then if it still shows a 5/7 miss you know its mechanical, if now 1/3 you know its electrical.

May be a waste of time but have you had a vacuum gauge on the engine (must be a mechanical gauge with a needle)? Different conditions will cause the needle on the gauge to react differently.

http://www.broncolinks.com/gallery_i...osisCraigU.JPG

Thanks guys - just wanted to post this. Finally got to #8 tonight... wow:
http://pafirefighter11.smugmug.com/A...MAG0173-XL.jpg

Car idles a lot better, drives a lot better, but is still missing on 5 & 7.

That may give you some more insight into cyls 5 and 7. That's a lot of crud.

Maybe a top end clean/seafoam is in order?

pull the covers and start the car

Yeah that's a lot of carbon deposit. Did it reek of fuel? I would do a top end clean or two.

UPDATE: SO, I think I may have found the issue, or a big part of it. I decided today to check things I have checked already, just in case I missed something, or see if anything changed. On my way home I stopped, unplugged the MAF, reset the codes on the PCM with my Torque app, and drove. WOW.... what a difference. CEL is not blinking, it's not even on anymore. I drove it 25 miles home. The car still has minor hesitation but no big misfire. Check out these screen shots:

http://pafirefighter11.smugmug.com/A...screenshot.jpg

http://pafirefighter11.smugmug.com/A...screenshot.jpg

I'll order up a new MAF and see if that fixes things completely!

Is your MAF descreened? I forget if I asked that.

The '01's is, the '98 is not.

Bad Maf does some crazy stuff. Just changed the one on the trailblazer. It was causing major shifting issues

glad your getting closer to fixing this, black magic stinks

I'd be leery of that fixing the issue, I hope it does though! Unplugging the maf will force the computer to use default spark and fuel tables. I'm not sure it will be able to calculate fuel trims either since its not reading air in. I could be mistaking though and I hope it is the issue!

Yeah if it was a bad maf it wouldn't be a constant 5&7 miss


Now the carbon deposit looks to be signs of babying the car way too much

Whatever the case, after 45 minutes of driving (25 miles) the CEL is off. EVERY other time I reset the PCM codes the CEL light came on within 1 minute, and flashed immediately when it hit 30+ MPH. I need to hook it up to EFI Live again and see what's going on.

Post #36. You said you checked all that out. ????????

Doesn't the car remain in open loop when maf is unplugged which means it not using the O2 readings.

ehhhhh it goes to its back up and uses the map sensor

It's definitely not fixed 100%, but the blinking misfire is gone. No P0300 code. Only code is for the MAF being disconnected. When it's warm it still idles pretty rough and wants to die at stops (though it hasn't). But once it's warmed up I'd say it's about 85% better than with the MAF plugged in. I'm going to have my AIR and EGR tuned out, to see if that further helps things as well. Anyone have a confirmed working '98 LS1 MAF for sale? :P

Try switching the maf from your other car then and see what it does.

i hve a maf for sale. on my forsale thread.