Misfire codes, due to bad cats?
#1
12-07-2015, 03:19 PM
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Misfire codes, due to bad cats?
I have a '05 G35x sedan (with approx 170K miles) and about a week ago the car suddenly began running very rough/misfiring. That said, I had AutoZone run the diagnostic via the OBDII port and it came back with misfire in cylinder 2 (P0302) and also a code for the cat converter came up. Based on the codes, I went through the fuel and ignition systems, checking all injectors, coil packs, coil pack connectors, and spark plugs. Everything checked out fine and the plugs didn’t even look too bad, but I replaced them anyways, with good NGK IX plugs. I also did a compression test and it came back great (180 psi across all cylinders). However, after replacing the plugs there was no change in the cars performance. So, I had AutoZone run the codes again and now it’s saying a misfire in cylinder 4, as opposed to saying cylinder 2 before. This all said, I’m thinking that the cat converter on the drivers side may be clogged/bad, as the misfire codes for cylinders 2 & 4 both correspond to the drivers side and as stated, the code oddly changed from cylinder 2 to cylinder 4. I’m just wondering if anyone else has had a similar issue and in the end, if the cat was the culprit. Any input from anyone, of any kind, would be much appreciated. Thanks!
#2
12-07-2015, 04:41 PM
Join Date: Mar 2011
Location: Central NJ
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Front and rear cameras, tire pressure for all four tires can display on screen,folding side view mir
I have a '05 G35x sedan (with approx 170K miles) and about a week ago the car suddenly began running very rough/misfiring. That said, I had AutoZone run the diagnostic via the OBDII port and it came back with misfire in cylinder 2 (P0302) and also a code for the cat converter came up. Based on the codes, I went through the fuel and ignition systems, checking all injectors, coil packs, coil pack connectors, and spark plugs. Everything checked out fine and the plugs didn’t even look too bad, but I replaced them anyways, with good NGK IX plugs. I also did a compression test and it came back great (180 psi across all cylinders). However, after replacing the plugs there was no change in the cars performance. So, I had AutoZone run the codes again and now it’s saying a misfire in cylinder 4, as opposed to saying cylinder 2 before. This all said, I’m thinking that the cat converter on the drivers side may be clogged/bad, as the misfire codes for cylinders 2 & 4 both correspond to the drivers side and as stated, the code oddly changed from cylinder 2 to cylinder 4. I’m just wondering if anyone else has had a similar issue and in the end, if the cat was the culprit. Any input from anyone, of any kind, would be much appreciated. Thanks!
http://www.nicoclub.com/FSM/G35/Seda...5_Sedan/ec.pdf
See page EC-301 to EC-310, 331
Good luck
Telcoman
#3
12-07-2015, 05:20 PM
Join Date: Jun 2013
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Thanks for the FSM info. After reading through the literature, I've gone through about as much of that as I can, without having a Consult/diagnostic device. The fact that the misfiring cylinder # has changed, seems to allude that it's not a fuel or spark issue..... Do you happen to have a link to the portion of the FSM that deals with the catalytic converters?
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