Spark Plug Preferences
Have you ever worked on a car?
Yeah, lets just throw an ECU at it! Thats only like what, a $500 bo-bo or so!
Spark plugs will cause a misfire under load, because as load increases, so does the resistance of the spark to jump the gap in the cylinder. If the resistance of the spark plug gap is higher than the resistance of say the gap where the wire is resting next to any piece of grounded metal, it will jump through the wire to ground, completely bypassing the spark plug, therefore causing a misfire.
Same with a vacuum leak. Engine is taking in X amount of air through the throttle body, and X amount of air through vacuum leak. The MAF only knows about the amout going through the throttle body. Lean condition (especially if it is in an intake runner) could cause a misfire.
How about a bad MAF? ECT? even a bad TPS can cause a misfire under acceleration!
I dont mean to be rude, but If I had no idea what I was doing, and followed your advice, and put a PCM in my vehicle, and it didnt fix it, I would be pretty mad.
P.S., I read a statistic (somewhere) that like 75% of all PCM's returned as defective, are actually just fine, and were returned because the problem was mis-diagnosed.
Have you ever worked on a car?
Yeah, lets just throw an ECU at it! Thats only like what, a $500 bo-bo or so!
Spark plugs will cause a misfire under load, because as load increases, so does the resistance of the spark to jump the gap in the cylinder. If the resistance of the spark plug gap is higher than the resistance of say the gap where the wire is resting next to any piece of grounded metal, it will jump through the wire to ground, completely bypassing the spark plug, therefore causing a misfire.
Same with a vacuum leak. Engine is taking in X amount of air through the throttle body, and X amount of air through vacuum leak. The MAF only knows about the amout going through the throttle body. Lean condition (especially if it is in an intake runner) could cause a misfire.
How about a bad MAF? ECT? even a bad TPS can cause a misfire under acceleration!
I don't mean to be rude, but If I had no idea what I was doing, and followed your advice, and put a PCM in my vehicle, and it didn't fix it, I would be pretty mad.
P.S., I read a statistic (somewhere) that like 75% of all PCM's returned as defective, are actually just fine, and were returned because the problem was mis-diagnosed.
I'm fairly certain that it says somewhere in the rules that only the original poster may start an aurgument on his/ her post. And if it doesn't, it should.
Peter94 is right, though perhaps a little harsh. The pcm isn't nearly as likely as the issues he suggested, especially regarding the vacuum leak, which was the case as one of the lines had dry-rotted and cracked.






