Cylinder 1 & 4 misfires
#1
11-13-2017, 09:46 AM
Cylinder 1 & 4 misfires
2001 Blazer 4WD. Trying to pin down the source of my misfires. It started as a P0300 that would be thrown usually any time I was on an incline at highway speeds (65-70) and had to punch the gas the get around someone.
Hooked it up to a Snap-on Solus Edge scanner, and it had a decent amount of misfiring on all cylinders, some more than others, but I couldn't feel them at all, not while idling or driving, and they never threw a code other than in the situation stated above. Replaced plugs (AC Delco Platinum), wires (duralast), distributor cap and rotor (would have to double check as I can't remember atm, but I think Valucraft), and the misfires definitely went to the lower end of the spectrum but were still there. Replaced the spider injector with the new style MFI (SMP) because I figured even if it wasn't the problem it would eventually need done. It did actually need it though, two of the injectors were leaking. After all of it, I still have misfires on 1 & 4. Double checked the gap on the plugs, all good there. CMP retard is reading at -6°, so maybe the distributor isn't lined up properly? I still can't feel it miss at all, and its not throwing a code either, I just see the misfires on the scanner. Scratching my head here.
Hooked it up to a Snap-on Solus Edge scanner, and it had a decent amount of misfiring on all cylinders, some more than others, but I couldn't feel them at all, not while idling or driving, and they never threw a code other than in the situation stated above. Replaced plugs (AC Delco Platinum), wires (duralast), distributor cap and rotor (would have to double check as I can't remember atm, but I think Valucraft), and the misfires definitely went to the lower end of the spectrum but were still there. Replaced the spider injector with the new style MFI (SMP) because I figured even if it wasn't the problem it would eventually need done. It did actually need it though, two of the injectors were leaking. After all of it, I still have misfires on 1 & 4. Double checked the gap on the plugs, all good there. CMP retard is reading at -6°, so maybe the distributor isn't lined up properly? I still can't feel it miss at all, and its not throwing a code either, I just see the misfires on the scanner. Scratching my head here.
#2
11-13-2017, 06:59 PM
2001 Blazer 4WD. Trying to pin down the source of my misfires. It started as a P0300 that would be thrown usually any time I was on an incline at highway speeds (65-70) and had to punch the gas the get around someone.
Hooked it up to a Snap-on Solus Edge scanner, and it had a decent amount of misfiring on all cylinders, some more than others, but I couldn't feel them at all, not while idling or driving, and they never threw a code other than in the situation stated above. Replaced plugs (AC Delco Platinum), wires (duralast), distributor cap and rotor (would have to double check as I can't remember atm, but I think Valucraft), and the misfires definitely went to the lower end of the spectrum but were still there. Replaced the spider injector with the new style MFI (SMP) because I figured even if it wasn't the problem it would eventually need done. It did actually need it though, two of the injectors were leaking. After all of it, I still have misfires on 1 & 4. Double checked the gap on the plugs, all good there. CMP retard is reading at -6°, so maybe the distributor isn't lined up properly? I still can't feel it miss at all, and its not throwing a code either, I just see the misfires on the scanner. Scratching my head here.
Hooked it up to a Snap-on Solus Edge scanner, and it had a decent amount of misfiring on all cylinders, some more than others, but I couldn't feel them at all, not while idling or driving, and they never threw a code other than in the situation stated above. Replaced plugs (AC Delco Platinum), wires (duralast), distributor cap and rotor (would have to double check as I can't remember atm, but I think Valucraft), and the misfires definitely went to the lower end of the spectrum but were still there. Replaced the spider injector with the new style MFI (SMP) because I figured even if it wasn't the problem it would eventually need done. It did actually need it though, two of the injectors were leaking. After all of it, I still have misfires on 1 & 4. Double checked the gap on the plugs, all good there. CMP retard is reading at -6°, so maybe the distributor isn't lined up properly? I still can't feel it miss at all, and its not throwing a code either, I just see the misfires on the scanner. Scratching my head here.
Best thing I can say to do is verify that the misfire detection can correctly detect a misfire. Pull the plug wire on a cylinder that is not currently showing as missing. Now it should show it counting misfires rapidly for that cylinder. If it doesn't you will need to figure out why the misfire detection is not working correctly and I would not trust any of the misfire detection further. Mine could not correctly identify an induced miss on my vehicle, on any of several cylinders.
Last edited by LesMyer; 11-13-2017 at 07:04 PM.
#3
11-25-2017, 10:54 PM
On my first blazer I went thru same thing. I done all that and still had the missfires. Ended up being the brand new distributor cap. It was cheap one from Autozone so my buddy said hey buy a good one and try it so I bought there gold version same problem. I read a early post on here years back when this was going on about how he swore his blazer would only run on a AC Delco cap and rotor so I said what the heck I’ve tried it all even tho it made me cringe to buy another darn cap but it was like night and day? I only buy AC Delco caps and rotors when it comes to my 4.3’s
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