Qx4 shaking

[robdancarter]

On occasion, but not often, when I start my 2001 Infiniti Qx4, the car will shake, even when idling. I've had it hooked up to a computer to see what the check engine light was blinking for, and nothing came up. I'm told it could just be a misfire. Does anyone know what could be causing this? Would changing the spark plugs help? They are about due for a change anyway.

Sorry if the shaking/vibration symptom isn't enough information but I don't know how else to describe it. I'll answer questions if you need more info.

[CanuckQx4]

If the CEL is flashing, then yes the car is reading a misfire. The 01's are notorious for having ignition coil problems, which were changed in later models.

Spark plugs would definitely be a great idea though, there about $10 each for the proper ones, I highly suggest buying ONLY the recomended ones.

After changing the plugs, I would run the car until it threw a misfire code for a specific cylinder and change that ignition coil.

Also the ingnition coil harness connector and very weak, maybe it is loose or broken, they are very easy to break the tabs when removing (maybe someone did it before you) and dont stay clicked on the coil

[robdancarter]

Thanks for the help. The estimate to change the spark plugs is $240 bc its a 2.5 hour job. The mechanic said he has to remove a lot of parts to get to some of them, so should I order the ignition coils and harnesses so he can just put them on if they are damaged?

The car shakes about one in every four days which is more often than it had in the past.

Is there any chance its the infamous o2 sensors that go bad on these cars?

[Towncivilian]

The CEL would typically trip if an O2 sensor was bad.

Are you mechanically inclined? It is not that difficult of a job to change the spark plugs; there is an excellent pictorial guide here.

[robdancarter]

Well the CEL definitely triggers. The CEL is always on and it blinks when shaking. I'll probably just take it in to get the computer reading on it. Or maybe I'll look at buying one of those diagnostic readers myself. Thanks for responding.

[asnorton44]

I would probably check out the MAF too.

[walletsworth1]

Has anyone tried the $170 complete sets of 6 coils on ebay?

Like: http://www.ebay.com/itm/Ignition-Coil-F ... 1110806934

I have this same intermittent misfire issue, and if these will function for another 2-3 years I am ok with doing it again later if the SUV still runs at that point.

[robdancarter]

Well I got my own OBD II reader on amazon (for only $25) and sure enough, it read that the "02 sensor circuit high volts (Bank 2 Sensor 2)" isn't working properly. Now I need to figure out how to get that fixed and how much it is going to set me back.

[Towncivilian]

That is the driver's side rear oxygen sensor. You can ignore it indefinitely (barring upcoming emissions testing since any CEL = auto failure), it has no impact on driveability. It is not causing your shaking issue.

[robdancarter]

Well I don't know if that is good news or bad news. The CEL wasn't on when I hooked the computer up so I guess I'll wait til it shakes and the CEL comes back on to see what it reads then. I really appreciate you telling me it doesn't need to be fixed though. Thanks so much for the help.

[sp4rtan]

The shaking does need to be fixed because, in my experience, it only gets worse. The O2 sensor does not need to be replaced until emissions.