Help - changed my plugs now H2 runs like @#$%

[dna]

After 200kms I thought it would be a good idea to change the plugs and wires for the 1st time. Bought the iridium (41-110) and OEM wires. With doing only limited googling, I thought these were supposed to be gapped at .06mm so I did that (they were 0.04mm out of the box).

After installed these new plugs, the idle was smooth and revved nice. Took it for a drive and the truck could barely get over 100 km/hr. After a few minutes I got P0151 (maf sensor) and p0300 (random misfires).

So I pulled all plugs out again and regapped back to 0.04. Installed them, but same thing. Could barely get over 100km/h and same 2 obdii codes.

Could I have damaged the plugs when I first gapped them? My method was sticking a flathead driver into the gap and lifting up - could this have damaged the iridium tip?? Is there anyway I can tell if the plugs are bad other than buying a whole new set?? BTW - I dropped one of them about 3' onto a concrete floor - when it first happened I looked at it and it looked fine. Could that have damaged that one, and is it possible if I have only 1 bad plug that I'd get these symptoms and codes?? I would have thought if only one plug was bad that the p0300 would have given me a number in the last digit to tell me which cyclinder is misfiring - doesn't p0300 mean all (or more than 1) cylinders are misfiring??

Thanks

[glennf1]

My bet is you either bumped the plug at the MAF during your plug swap or there is a break in that wiring. Without the MAF signal it will do exactly what you described.

[dna]

Checked the maf plug and it was fine. Still have the issue. I guess it could be a coincidence and my maf sensor has gone bad. Is there a way to test the sensor?

Otherwise if maf is good and maf plug well connected, any other ideas?

Could it be my cat. I have one that is going bad. Been looking for a replacement for a few weeks now. Though prior to the plug swap, only issue I had was rattlin (no codes). Maybe with the new plugs and wires, with the extra power it was enough to fully plug my cat. Heard that a plugged cat will give p0300 codes - though would that also give the maf code?

Thanks

[glennf1]

MAF itself could be bad or the wiring from it going to the computer. My only other guess would be a forward O2 sensor. If your cat was bad the rear O2 would catch it and that's only for emissions anyway, the forward O2 is for Air/Fuel. The codes are your friend.. it would not have thrown a MAF sensor code unless it was out of range or not receiving feedback from it. Unplug your MAF sensor and drive it. If there is no difference I would replace it.

[inputapmech]

I think your spark gap is 1.02mm.... That might be the problem

[Camou2]

Originally Posted by inputapmech

I think your spark gap is 1.02mm.... That might be the problem

1.02mm is the same as a gap of .04 and that is what the plugs should be gapped at,, suspect just coincidence but probably MAF problem

[glennf1]

Did you ever figure it out?