Random Rough Idle

[PyMets520]

I have a 93 Q with 83k miles..As of late I have been getting a rough idle. I consider it random b/c one day i can start the car and it drives fine, with no problems. I can start the car again later in that day and the car shakes and i can feel it slightly as i accelerate, and it does not go away while i drive. So the rough idle is not consistent, but is noticeable. While searching the forums I came across two ideas of what it may be:One being the MAF needs to be replaced or cleanedTwo maybe the vacuum hose, since i had replaced the old 1 which was ripped (a few months ago) with a new hose, but not an "L" shaped hose.

Am i thinking along the right track?

[maxnix]

Attack the MAF connectors first.

Without a maintenance history, tough for us to guess any better.

[sdkhalsa]

Attack the MAF connectors first.

Without a maintenance history, tough for us to guess any better.

What is the history on injectors? One maybe starting to fail. Have you taken resistance readings?

[PyMets520]

What is the history on injectors? One maybe starting to fail. Have you taken resistance readings?

I don't believe any of the injectors had been replaced. I got the car with 72k miles on it, and just recently i had a new rack put in.

How would I go about checking their resistance?

[maxnix]

You can check easily through the harness.

There are posts here in IOM and at Q45.org.

[PyMets520]

Two quick questions:1) When checking the injector resistance should I disconnect the battery before i check the resistance?

2) I noticed today that there was some noise coming from the trunk when i put my head in, fuel pump im guessing, it sounds like a faint buzzing or liquid sound, would that be the cause for the intermittent rough idle?

[96Qowner]

1) No, but take the key out of the ignition and make sure the doors are closed and everything turned off = no current draw in the system.

2) The fuel pump isn't causing the rough idle. If it isn't buzzing loudly, you have some time left before replacement - keep an ear on it and budget for it within the next 20k - 30K miles or so.