CStewTAMU

I have had trouble with my car idling roughly and erractly. It has even died a few times. The tach needle will usually idle at about 700-800 RPM but jump up and down + or - 300rpm only when idling. As soon as I give it gas, all is good, runs smoothly.

I have tried throttle body cleaner and that didn't seem to do anything.

Any suggestions on what my problem is and how to fix it?

The SES light came on at about the same time my rough idle problem started. And I pulled a code 48 with my trustly old paperclip.

What are the most likely causes. I figured if I had bad plugs, wires, or Opti, it would miss and run roughly at all RPM ranges. Is that necessarily true? I figured it the throttle body was just getting stuck due to carbon buildup, TB cleaner would fix this-at least temporarily.

Also, what symptoms would a bad MAF sensor be? What exactly is the MAF sensor's job?

TIA

jimg's'93

My '93 FSM doesn't even show a DTC 48, but I'd check your IAC sensor and possibly your ERG system.

TWISTERUP

Since you say it runs great off idle--i'd check for vacuum leaks first around intake manifold and the vacuum hoses which run to it---use the throttle cleaner and spray around the above areas--rpms will increase if the cleaner is "sucked" into the area of a leak. Could be internal leak in brake booster---also be sure the bellows hose between MAF and TB has no cracks in the rubber and is tight.

Your problem could be bad MAF--connectors or harness between MAF and ECM. Start w/basics first though and check for vacuum leaks. Also if you've done any recent work which involve gaskets or hoses which could leak vacuum--check there first JMO :thumb BTW a vacuum leak is one of the things which can set a code 48

600RR

Is there a "hiss" sound comming from the motor? Is it running like there is a cam in the motor? I had a prob simular to this and I found that the previous owner had replaced the MAF sensor but did not replace the rubber garmet that goes between the sensor and the intake. Fixed my 92, gas milage went up 3 gpm also :P