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Re: 91 900s fuel/drivability Posted by Saana88 [Email]  (#207)  [Profile/Gallery]
(more from Saana88) on Sun, 24 Apr 2005 20:30:27
In Reply to: 91 900s fuel/drivability, Laura, Sat, 23 Apr 2005 09:55:43 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hmmmmmm..... That's a tough one. I've said this before, but these wierd cars have some wierd problems sometimes.
I know every time you fill up the tank the charcoal canister floods, but to what degree I am not sure. It is supposed to feed the fuel vapor back into the intake manifold instead of venting it into the atmosphere, an emissions control trick.
To begin with, are your vacuum lines, grommets, and (sorry, it's the correct word) nipples in good shape? Lots of times if the plastic nipples don't degrade and the hoses don't develop leaks, the rubber grommets around the fittings will become brittle and hard due to age and oil exposure and heat and the like. Don't miss the grommet around the PCV vent lines at the top of the valve cover. While you're in there, be sure that breather still breathes- look for sludge and deposits.
Do you have any major oil leaks? Anything that would indicate the PCV system being pressurized due to blockage? This is an old brick trick. Thank God these things have permanent flametraps.
You should also see a small, cylindrical check valve in the vacuum line that heads toward the firewall. On my convertible, it tees into the cabin vents and the reservoir, sedans may be different. Either way, make sure that check valve is installed the right way (airflow arrow away from the intake manifold) and that it works as a valve still.
Any time the idle sticks I suspect two things, the AIC valve and the throttle body. Take off the rubber hose from the throttle housing and clean around the butterfly valve. If too many deposits build up in there it'll wreak havoc with your idle. The same problem (which I'm playing around with on my '92) is a dirty Air Idle Control motor. That's the cylindrical solenoid in a bracket near the front end of the injection rail near the valve cover on the distributor end. This valve has a three-pin connector and two rubber hoses running to the throttle housing, one before and one after the throttle valve. Take the valve off and spray some penetrating oil into the openings. Gently swab out any crud with a rag, but I am careful not to jam the rag into the moving parts inside.
After this, get back to us.... I'll walk you through testing the throttle position switch (actually a potentiometer) and the engine temperature sensor. If the throttle position sensor tells the computer that it's wide open when it really is not it will goof things up, as will a poor-reading engine temp sensor. You'll need a voltmeter and about 20 minutes for these tests.
Good luck! Low, low mileage.... Take good care of it.
, Sun, 24 Apr 2005 20:30:27 <-- Viewing This Message
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