Im still having either really high idling or really low idlin, but only while the car is in drive. Ive cleaned the throttle body but im stumped on this one...

 

I wonder what the problem could be, in other words, more information would be helpful.[sm=violent053.gif]

 

Basically this pretty much started out of nowhere. When my car is in park the idle seems to go up to 1700-2400rpm and when I put the car in drive, the idle drops to about 900rpm or less. Im not sure what to do. I cleaned the throttle body because I heard that a dirty one could cause uneven idiling.

 

Hmm, based on my experience, this sounds like perhaps idle switch adjustment issues.

an example...
https://volvoforums.com/m_54247/tm.htm

in any case, you'll want to check the throttle body over. As you play with the throttle plate you should hear a miniscule click, ever so slight. This is the throttle position sensor switch. You should notice that to take off the throttle body to clean it it is necessary to detach the throttle link bar. Thsi bar, on my 744, is brown on both sides and with metal in middle.(I wish I had the care to take pics, perhaps if you are diligent!) You can adjust the throttle linkage to where as the throttle is left alone and closed it is at default. As you just barely turn the throttle you should hear that little click. this is imperative for proper function of idle. Also check for vacuum and air intake leaks.

 

I can hear the clicking of the throttle position sensor switch so should I adjust it until the idle returns to normal?

 

there are two points of adjustment, one being the adjustment screw on the throttle body and then there's the throttle linkage bar which connects the throttle body to the throttle pulley. For reference, the throttle pulley is the aluminum disc thingy which has the metal rope/string.

Number one, you want to first observe the mechanical principal of the throttle body and the click of the throttle switch. after which you should then find the correlation of the adjustment screw and how it stops the thottle plate/butterfly from rotating about the axis...upon which it rotates via spring. so adjust the adjustment screwso that you hear the click just prior to the plate being stopped be the screw, and just after you open it up.
Number two, you'll need to make sure you understand the principal of the throttle linkage and how that all works. Once you get it all connected be sure you hear that click when you allow the throttle to close and open. If you understand the principal of the throttle assembly, which is not too hard just take your time, you can see how to adjust the adjustable throttle linkage.

I do hope I'm not being too inept, good luck.[sm=smiley29.gif]

 

I brought the car over to my friends shop today and we narrowed it down to two possible things. Either a faulty air mass sensor or a vacuum leak. He didnt have much time to look it over today so hopefully tomorrow we will figure it out. I was looking at air mass sensors on vlvworld.com and the prices were pretty steep. Would I be better off going to a junk yard and picking one up? (If this was the problem)

 

Did you all pull the codes to see what the ECU is faulting? This may help lead you in the right direction and give you a clue as to what the problem is. If it is the MAS the ECU will sometimes fault it, if its a vacuum leak you'll get a lean shift code. I would try that before you start changing parts.

 

.....how old is the battery/alternator? If the codes yield nothing, check that out too. My 91 240 had running issues in drive because there wasn't enough spark to push the car against the transmission.....ran fine in Park though

 

We ran the codes and it was in fact the mass air sensor. Thanks for everybodys help

 

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