RPMs go up after putting in Park or Neutral [Archive] - SaabCentral Forums

: RPMs go up after putting in Park or Neutral


PianoDavid
22nd November 2005, 12:24 AM
well ok, my car's had a LOT of problems, and at one point i did adjust the idle - a lot. anyway, when my car is in Drive (automatic) and my foot is on the brake (or just not on the gas) it idles around 850 - like it should. after a short, long, or no drive at all, if the car is put in Park (or Neutral) the RPMs go up to 1600, then slowly go down to 1400--but never all the way down to 850. but as soon as i put the car in Drive again (OR Reverse OR 1 OR 2), RPMs DROP down to 850. is this a transmission problem???? i sure hope not. how should the idle be adjusted? when the car is in Neutral? Drive (parking brake) or Park?
thanks
-David

Matt88S
22nd November 2005, 01:00 AM
Idle should be adjusted in park. How did you adjust your idle? An 88 900 turbo in the US should not have anyway to adjust the idle, it should adjust automatically. :confused:

There are things that can cause a high idle, vacuum leaks, faulty sensors, sensors out of specs, etc.

The reason the idle is dropping when you put it in drive or reverse is putting it in gear loads the engine down and that pulls the rpm's down. Engaging a autobox with a 1400-1600 rpm idle will eventually tear your tranny up. :lol:

ProfZ
22nd November 2005, 02:11 AM
Check that your TPS (throttle position switch) is adjusted correctly. Look in the Bentley manual, or search this Forum for details.

tonyw
22nd November 2005, 06:24 AM
Idle should be adjusted in park. How did you adjust your idle? An 88 900 turbo in the US should not have anyway to adjust the idle, it should adjust automatically. :confused:

There are things that can cause a high idle, vacuum leaks, faulty sensors, sensors out of specs, etc.

The reason the idle is dropping when you put it in drive or reverse is putting it in gear loads the engine down and that pulls the rpm's down. Engaging a autobox with a 1400-1600 rpm idle will eventually tear your tranny up. :lol:

Hi all, I have a similar situation (I wouldn't call it a problem) in that my RPM goes up to 1300 after parking and engaging neutral AFTER a trip. When I switch on and start up prior to setting out, the RPM is normal, at 850.

Would that better describe the situation Piano David has? My car is an '89 900i, by the way.

Matt88S
22nd November 2005, 11:13 AM
Hi all, I have a similar situation (I wouldn't call it a problem) in that my RPM goes up to 1300 after parking and engaging neutral AFTER a trip. When I switch on and start up prior to setting out, the RPM is normal, at 850.

Would that better describe the situation Piano David has? My car is an '89 900i, by the way.



Yes it would. In fact, it sounds like the problem I have with my 87S. :p

Talk about the blind leading the blind. :p Ok, maybe not that bad, and mine's a standard so its not such a big problem, I just load the clutch a bit as I shut it off.

I wouldn't call it a problem

I would, its hard on autoboxes to put them in gear at a high rpm, and a high idle will also cause your engine to diesel when you shut it off, that will also damage your engine over time. So its kind of a problem, something that should be taken care of before to much time goes by.

cheers

PianoDavid
22nd November 2005, 04:30 PM
yes tonyw my car does that. well - when first started (in P obviously) the car idles around 850ish, however, if engaged in any moving gear, then back out of that gear (into N or P) the RPMs go up. there isnt any nasty noise when the gears engage, but even with your foot on the brake pedal, the car does pull a bit at first - like if you're holding it back (well . . . you are) - would this be a big problem still? even though there is NO noise (i.e. gears grinding = BAD) - you hear the engine RPMs drop but thats it.

Check that your TPS (throttle position switch) is adjusted correctly. Look in the Bentley manual, or search this Forum for details.
i really do need to get one of those manuals - im a poor college student - anyone know where to get one cheap (online) or U.S. national (chain) store? i really dont mind if its used.

Matthew
22nd November 2005, 06:09 PM
You could search somewhere like EBay for a second-hand manual, or put something in the Classifieds perhaps. Even second-hand bookshops might be worth a look.

PianoDavid
26th November 2005, 09:02 PM
Check that your TPS (throttle position switch) is adjusted correctly. Look in the Bentley manual, or search this Forum for details.

I've adjusted the TPS (actually the dashpot was holding it open) - i pulled the throttle open softly, to simulate conservative driving/letting off the throttle, and i shut it hard to simulate as if someone'd cut me off. i did this like 23456 times and every time - click-click. so i'd assume its good. idle now only goes up to 1000 instead of 1600 out of gear. - i've got a few rubber gromets to replace before i do anything else (brake booster tube on manifold primarily).

but just to clarify, this is NOT a transmission problem right?
thanks, David

Matt88S
26th November 2005, 10:06 PM
but just to clarify, this is NOT a transmission problem right?


The high idle? No, its an engine problem.

PianoDavid
26th November 2005, 10:15 PM
ok good i was just wondering b/c it only when high when taken out of gear - i thought maybe because of that it would be a trans. (or engine/trans) problems.

tonyw
28th November 2005, 05:31 AM
I've adjusted the TPS (actually the dashpot was holding it open) - i pulled the throttle open softly, to simulate conservative driving/letting off the throttle, and i shut it hard to simulate as if someone'd cut me off. i did this like 23456 times and every time - click-click. so i'd assume its good. idle now only goes up to 1000 instead of 1600 out of gear. - i've got a few rubber gromets to replace before i do anything else (brake booster tube on manifold primarily).

Hi PianoDavid, Sorry to be a pain, but I really am clueless when it comes to engines, so first, is the TPS adjustment easy to do, and second, if so, could you tell me how you did it? Many thanks!

PianoDavid
28th November 2005, 07:02 AM
the TPS is (supossed to be) adjusted by the two small (7mm?) bolts that hold it on to the TB itself. these adjust the TPS's position relative to the throttle plate. As it turned out for me, my TPS was fine, my dashpot was holding it open, and the ecu was not usning the idle map (setting). The TPS should click just as you pull on the throttle cable - telling your engine that it is at cruise, and not idle, and then it should click again as the throttle is released (do this slowly to hear the click--its soft). also, this is done by pulling the throttle cable (bottom of the 2 if u have cruise control) with your fingers - engine OFF.

I would have to assume this would be a pain in the neck of some sort (hey its not all fun and TURBO). - because like Matthew says, you get it just perfect then you'd tighten down the bolts and whammo its out of place again.

Check Matthew's post http://www.saabcentral.com/forums/showthread.php?t=34997 for more info. - DEFINETLY do them in the order he suggusts - my throttle cable had also been wound WAAY too tight, and was also holding the throttle plate open/causing high idle.

abekus
28th November 2005, 02:35 PM
Check the electrical connection to the temperature sensor that goes into the manfold, inline with the fuel injecotrs. I have an extra Bentley's brand new in the box, never been looked at. An extra one got shipped to me before I could get the order cancelled. E-mail me we'll talk about it.