Post your car questions here

[Underhill]

How useful is the "Car MD" device I've seen advertised on late night tv? Is it really capable of accurately diagnosing problems?

It's just a code reader. Autozone will read your codes for free.

But do the codes it reads refer to specific problems, which I expect are listed in some accompanying reference manual?

If so, go back to my original question. Are these devices usefully accurate?

I'm no expert, but here is my experience.

I don't know anything about that particular model reader but they can be. If your check engine light comes on they can often tell you why. Although it can be vague.

I used one a while back on my wifes Durango and the code came back with something like a fuel system error. Which upon researching it could be one of a dozen different things. So I started at the most likely and worked my way down.

But it can give you codes for specific sensors etc...

They are virtually no help for many mechanical problems, but they do make life easier for electrical issues. If nothing else it will often narrow down the problem letting you know where to look.

My big question for the factory mechanic here is this. Is there a difference between the readers I've used from Auto Zone and those used at the dealer?

 

[Jarlaxle]

You can get a code chart, but really don't need one...if you get a code, just plug it into Google.

 

[KissMy]

How useful is the "Car MD" device I've seen advertised on late night tv? Is it really capable of accurately diagnosing problems?

It's just a code reader. Autozone will read your codes for free.

But do the codes it reads refer to specific problems, which I expect are listed in some accompanying reference manual?

If so, go back to my original question. Are these devices usefully accurate?

Your car's computer is what detects & logs the problem. The device just shows you the codes the computer logged. There are better ones that allow you to see the real time sensor readings on your laptop computer. Better yet there are nice ones that let you view & change your car's program for more power, speed, mileage, emissions, etc.

The code does not tell you exactly what part to replace. For instance the codes may indicate that #4 cylinder is misfiring & the oxygen sensor is out of range. The oxygen sensor is likely fine because #4 cylinder is not burning the oxygen & it is going down the exhaust pipe where the oxygen sensor detected to much O2. It could be a bad spark plug, wire, coil, valve, piston, injector, gasket, etc on #4 cylinder causing those codes.

 

[KissMy]

Kissmy wrote: Did you change the Spark Plug Wires? Sounds like moisture on the plug wires is causing them to arc.

Yes, plug wires have been replaced...

... just called the mechanic...

... and he says it's the computer.

It does not sound like a computer to me. Try spraying water on wires & sensors after is is warmed up & running good. See if that makes it act up. It could also be temperature sensors or timing sensors.

Your Ford truck problem sounds just like the one Papawx3 posted here. It was the Crankshaft Position Sensor & apparently it did not log codes to make the check engine light come on for the mechanics computer to read.