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misfiring problem on 95 LS400
Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 31
Likes: 2
From: Georgia
misfiring problem on 95 LS400
Hello, just joined the forum because it seemed to be the one always popping up during my searches so it must be the best Lexus forum. Anyway, bought my first LS seven and a half years ago, a 1995, drove it four years and wrecked it. Been without one for three and half years until I just bought another 95 a week ago. Drove it for 3 days and 335 miles, it drove and ran like a new car, the 4th day it developed a real bad misfire, I ordered an Innova 3140 scanner and the 3 codes pulled up were #2 piston misfire, #7 piston misfire, and random misfire. Before the scanner arrived I switched out the top coil(the easy to get to one) and the misfire was still present. Still have the wrecked one I can scavenge parts from. My question is what should I check next, since pistons 2 and 7 are on opposite coils I figure it's probably not them. Thanks in advance.
Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 31
Likes: 2
From: Georgia
LScowboyLS, how do you get the driver side coil off. I have removed the distributor/wire cover top piece, still can't get to the other 2 screws. Also noticed piston 1 and 7 are on the driver side coil and 3 and 5 on the passenger side coil. Not sure about the other side but it's possible 2 and 7 are on the same coil.
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Driver School Candidate
Joined: Nov 2009
Posts: 5
Likes: 0
From: NC
I bought my car and it ran great for 2 days. Then it started throwing codes for a cylinder 3 and 5 misfire and had a really bad hesistation. I replaced all the spark plugs and the plugs on those 2 cylinders were finger tight. I literally broke them loose with just my fingers on the extension. I'd definitely look at the plugs and wires first.
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Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 31
Likes: 2
From: Georgia
Switched out the driver side coil and problem is still there, passenger side was already done. Checked the #7 plug and it seemed to be OK, not loose or anything and it was a NGK plug so it looks like the plugs have already been changed once. If I get new plugs, wires, distributor, and rotor, should I get Denso/OEM or are other brands OK?
Lead Lap
Joined: Jun 2008
Posts: 421
Likes: 0
From: indianapolis
I was getting p0300 random misfire, I solved the problem by cleaning the fuel injectors, now car running fine + with no CEL codes and even the fuel trim values are lower and within specifications +-10 % on both banks.
Last edited by qewani1; Aug 5, 2012 at 11:53 AM.
Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 31
Likes: 2
From: Georgia
Finally was about to put car in shop but decided to try new plugs(Denso Double Platinum) and wires(Denso) before I did that, believe it or not that fixed the problem, running like new again. How 2 plugs or plug wires go bad at the same time, I don't know. Both front catalytic converters were also testing bad and now after about 50 miles no check engine light is coming on for them either. Maybe the bad plugs/wires was causing them to not function properly also, they were throwing a check engine code even before the misfiring problem. Plugs and wires had been changed before because it had NGK plugs and Yazaki wires, my dad got over 300k on his original plugs and wires before changing them out.
Had an extra coil wire, there were 3 in the box, anybody know what that's for, also the wires were in a Denso box but Denso wasn't written anywhere on the wires, anybody know if they come unmarked like that.
Had an extra coil wire, there were 3 in the box, anybody know what that's for, also the wires were in a Denso box but Denso wasn't written anywhere on the wires, anybody know if they come unmarked like that.
Last edited by LORAN; Aug 18, 2012 at 05:00 AM.
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