Random Misfire 2002 LS v8 Sport

[2002LSv8Sport]

OK I bought this car yesterday. I noticed at around 80 km/h it starts to shudder. I attributed it to the torque converter locking on 1500 rpm. When I got home the check engine light came on and it gave me a "random misfire" code on cyl 1. I cleared the code and drove it around more (to see if when the check engine light came back on it would be the same). When it came on again it said "random misfire" on cyl 3. The car runs perfect at idle. The seller told me that he got the drivers side valve cover gasket replaced (I have the bill). I'm guessing that the coils were damaged by the oil and are just weak and need replacing, since it only misses under load. I plan on replacing coils 1 and 3, and all 4 spark plugs on that side (i'll get 8 plugs just in case). Am i on the right track or am i missing something?

 

[Town]

What code did you get? A P0300 is a random/multiple cylinder misfire while P0301 thru 8 would be misfire on that cylinder with the last digit of the code. You could have other problems beside plugs and COPs.

Since COPs are quite expensive, I would inspect the plug wells for oil while replacing all the spark plugs with a known reliable plug such as the correct model of Motorcraft. Also inspect the boots for signs of deterioration since they can be replaced separately. If the problem persists then swap COPs 1 and 3 for two other COPs and see if the misfire shifts with the COPs.

This Lincoln Tech forum article: http://www.lincolnforums.com/forums/threads/10712-Lincoln-LS-Spark-Plug-replacement may help you with changing the plugs and COPs.

Good luck.

 

[2002LSv8Sport]

Ok I checked it again for the 3rd time and the codes were "Random Misfire"0300 and now this time also "Misfire on cyl 2" P0302 It changes each time the light comes on? Could it be a plugged cat? the 02 sensor? I got a good code reader that can monitor all of these things in real time. I'll check voltages. Well I work at a Ford dealership so i get parts and labor cheaper. I do plan on doing the work myself (I got a buddy to help me). Oh on another note, the airbag light is also on. All the controls work on the steering wheel so i don't think the clock spring. Thanks for your help. If I find oil in the wells i guess i'm doing a valve cover gasket. why screw around right?

 

[Town]

The P0300 Random misfire means that a number of cylinders are misfiring and could be on either bank, but your cylinder specific codes seem to be on bank 1 only. A plugged CAT usually shows up as deteriorating performance under load, and possibly a P0420 for CAT efficiency below threshold (excess oxygen relative to flow on downstream O2 sensor) but your symptoms are different. A O2 sensor problem could lead to a lean mixture but that would be a long shot since the PCM tests the O2 sensor for response to different fuel ratios. A bank 1 intake leak is unlikely since your idle is good, and an EGR problem would affect both banks.

The air bag light will blink a lamp fault code (LFC) that will help with diagnosis. Your Ford scanner can interrogate the restraints control module to determine the DTC for the air bag fault. You often need both DTC and LFC to more accurately trace the problem.

Good luck.

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[2002LSv8Sport]

It misses on one cyl (or one at a time) at idle, You can't hear anything but you can feel it. It's not a steady miss just once every 2 or so seconds. I'm thinking that the boots or COP's are damaged since there is recorded valve cover gasket failure. I got 4 boots and 4 plugs for the one side (gonna do all 4) it cost me ~$50. Each coil is $45. It's great being a Ford employee.

EDIT: I think maybe more are failing because it seems to loose more power than I would expect just from 1 cyl when under load. I'll try replacing the boots and plugs this weekend and see how it goes. If that does not fix it i'll switch the coils from bank 1 to bank 2. Then see if it trips a misfire on bank 2. If so then it's a coil or two.

EDIT2: Now that i think of it. My buddy had a similar issue with his 2004 Dodge SX 2.0. It misfired randomly on all cylinders. We tried replacing the plugs first. That helped for a couple days, but then the problem persisted. So we changed the cam position sensor. That cured another problem with the car but not the misfires. His dad and I pulled out the spark plugs to check compression. It all checked out OK so we went to deliver the car to him at work. We noticed that it ran better, but as we drove it, it ran worse and worse. We decided to stop at Napa and get plug wires. That cured the problem to this day. Moving the wired around cured it for a little while. Weird but i hope thats the problem.

 

[Town]

You have COPs and not coil and plug wires. Low tension wires connect each COP to the PCM for individual firing. COP is Coil On Plug ignition. Not likely the wires are a problem although the connections could be.

Good luck.

 

[2002LSv8Sport]

Ok changed the spark plugs and the boots. Definitely helped the issue. Lots more power and smoother acceleration. But it still misses every now and then at idle, more so once it's hot. I'm thinking the next thing i should do is look at the PCV hose under the intake manifold. I think that's where it is. I think i'm going to do the spark plugs/boots on the other side anyways. If its not the hose i'll have no clue as what to do next.

 

[2002LSv8Sport]

Replaced the spark plugs and boots on bank 1. Problem solved thread can be closed. Thanks for your help Town.

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[Town]

Thanks for the resolution update.

Good luck.