For the last month or so when my G was at idol, I would feel a bizarre thump. It almost felt like a 6 year old kid was kicking the underside of my car. Service said it sounded like it was "dropping a cylinder". Any thought on what would cause this to happen on a G with only 15k?

 

I'd only feel this when I put it into gear.

 

Could be a number of things...bad coil pack, bad plug, bad injector. What error codes come up on diagnostic?

 

There isn't one. Actually the Infiniti is saying that since there isn't a code, they have to wait till it reproduces it. Yesterday, it did it 4 times in under a minute with a service tech in the car with me, but now it refuses to. They're about to just give me my car back and wait till it gets worse since they have no idea what cylinder to check and what not. Very frustraiting.

 

That doesn't make any sense to me and I would try a different dealer. They should easily be able to do a "power balance" test with the Consult tool to determine which cylinder is misfiring.

 

Well, it finally reproduced with the computer equipment hooked up. It didn't tell them which cylinder, but they have a general idea by how the ECU was trying to adjust the air/fuel mixture to compensate for the misfire. The tech said it's probably an ignition coil and it may be easier to reproduce with higher humidity levels. We'll see what happens today I suppose.

 

Make sure they did a power balance test to determine which cylinder does not produce a momentary engine speed drop. Then, they should check each injector, coil and plug. Good luck.

 

Thanks for the info!

 

Thank YOU!! I went to the dealer in Alexandria, VA about this and they did not know what was the problem, so they told me to come back when it gets worse. I guess I'll just have to do what you did and introduce them to this forum.

 

Good luck eddwin. I have a feeling this happens a lot more frequently then we've seen on these forums.

 

So no one else has had this issue? If you have, could you post the solution... maybe that will give them something specific to look at. Unfortunately, they have yet to locate the issue.

 

Wow...it's been a week and they can't figure it out? What happened with the power balance test? Did they try replacing the coil packs one by one, or testing the resistance on the injectors? It sounds like they've been letting it sit...

 

They have a whole parts department, they are lazy $hi+s if they cant even just throw parts at it till its fixed. Dont waste your time with them if they rely on trouble codes. Its very easy to go into the computer and look at the data moniters and see exactly whats going on.

IMO a power balance test is no good, it will tell you a bad hole, but not whats wrong. The best way to diagnose drivability and engine preformance (not as in high preformance) problems is to use the old school SUN ignition scope and a 5 gas analyzer. Its not just a meaningless graph like a power balance test. YOu can see your firing voltage and amprage at each plug on each fire. That combined with the 5 gas reading will tell you exactly whats wrong. You can feel the car running rough, the power balance test will just show you a graph telling you that the engine is not running smoothly.

 

Any mods involving wiring? It might an electrical problem. I had a similar experience and needed some rewiring work.

 

IT could be as simple as a little moisture has collected in your gas tank. Or you could have just got a bad tank of gas. I hope it could be that simple for you.