Wifes car 94 Infiniti J30 POS

Check engine light came on and it has a real rough idle/shake at lower RPM's(idle-1800), but dissapears above 2000 RPM. I think one cylinder might not be firing, but I dont know a lot about these things. Any help would be greatly appreciated. Does AutoZone do any diagnostics, cus Im trying to save some cash? Thanks again guys.

Matt Sandt

 

autozone can read any codes thrown.
if its missing, it should throw a code
you might try an inductive timing light and clip it to each cylinder to see if they are all firing.

How many miles since the last major tuneup?

 

No telling when last major tuneup was. It has 106,000 miles on it, and was her grandmothers, she got it a year and a half ago. Her grandmother took good care of it, had all the scheduled tune ups, but it is getting worn out I think. Thanks for the help

Matt Sandt

 

The Infiniti is a great car. Some of the earlier Infiniti's had a problem with bad oxygen sensors, but the only way to locate which one was to get a computer analysis. My I30 had three O2 sensors and all three were replaced three times in a short period of time. The problem was eliminated after a bad injector was replaced.

 

the ECM should log anything out of parameter. Past that, I would say its a bad plug or plug wire if its really misfiring.
The Infinity is based on the Nissan platform, but I dont know much about the 3.0 engine. Im more familiar with the 3.3 and its an older design of engine.

 

Also check the fuel pressure regulator.

MikeyB