A few problems that need answers.

[rivet0r]

*note : car is completely stock.

I bought my 90 Laser about a month ago. There are a few things wrong with it so I'm going to try and explain them as best I can in hope that someone can help me.

First, I have an idle problem. It fluxuates from 750 (norm) and drops down pretty low sometimes, 500 i would say. It begins to run rough until it goes back up. Yet sometimes even when it's idling at 750+, it still is rough. I don't know if it has anything to do with it, but the stock boost guage also moves when this happens.

Second, with a full 16 gallon tank, i'm getting 180 miles to the tank.. that's horrible. I'm not running rich, and the plugs are white. I had my car hooked up to a datalogger and the O2 sensor was doing its job just fine. I installed a new fuel filter the second day having the car, and i'm not sure i was getting bad milage before this or not.. could the fuel filter play an affect? Again, i'm not running rich at all, infact i'm running lean.

These two are the more serious questions that I would like to fix first, so I will limit this post to these two questions alone in an attempt to receive better info and hopefully a fix to the problems. Thanks for the help..

 

[rivet0r]

Originally posted by Defiant
Just to clear up Demon's typing a little- the O-ring on the BISS, Base Idle Set Screw. Check the VFAQ.

I took the BISS out and the o-ring looked fine.. should I change it anyways? Also, when my car is idling, i hear a hissing sound from around the throttle body.. Could some kind of vac leak cause this wierd idle? Or what about my horrible gas milage? Could clogged injectors be causing me to get 10-12mpg? Thanks again..

 

[street demon]

You need to make sure the oring is not flat.
The oring should be round and soft.
I would replace it anyway.

Auto Zone has them for about thirty cents.

It also sounds like you make have a vacuum leak. VERY lightly mist gumout around the area and if the idle changes you have a leak.
You can then isolate the leak.
If your cold air intake tube is off when you hear the hiss that is a normal sound.

P.S. to the guy who spoke about my typing.
I am a mechanic for God's sake, not a friggin' english teacher!