High Idle only in Park and Neutral
#1
02-17-2011, 12:16 AM
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High Idle only in Park and Neutral
I've got a '91 740 NA with 178k miles on it, and I just cleaned out the throttle body yesterday. It definitely needed it, and I could feel a huge difference when I took it out afterwards. However, when I got back and parked it, the idle sat between 1300-1500. This was not the case when it was in gear - stopped at a light, it sat happily around 8-900 and idled smoothly. It certainly didn't do this before I cleaned the throttle body.
I've got some vague, uninformed theories - did I somehow accidentally plug one of those tiny, tiny holes right above the butterfly flap? Did I somehow dislodge something to aggravate my IAC? I don't know.
Some possibly unrelated info: I've got a 232 code, which I had before the TB service and which I've been told is the oxygen sensor, although I check vacuum hoses first by habit. I cleared the code after the TB service, but it came back fairly quickly. Also, it was giving me some serious trouble starting (which it has done off and on in the past few months - a new battery seemed to make the problem go away for a week or two, but who knows?). Since it wouldn't start, I switched the fan relay and radio noise suppression relay - the car started right up, but soon gave me a CEL and a 113 code - fuel injectors. Would the relay have somehow triggered the fuel injector code, or...what else could I have done?
I've got some vague, uninformed theories - did I somehow accidentally plug one of those tiny, tiny holes right above the butterfly flap? Did I somehow dislodge something to aggravate my IAC? I don't know.
Some possibly unrelated info: I've got a 232 code, which I had before the TB service and which I've been told is the oxygen sensor, although I check vacuum hoses first by habit. I cleared the code after the TB service, but it came back fairly quickly. Also, it was giving me some serious trouble starting (which it has done off and on in the past few months - a new battery seemed to make the problem go away for a week or two, but who knows?). Since it wouldn't start, I switched the fan relay and radio noise suppression relay - the car started right up, but soon gave me a CEL and a 113 code - fuel injectors. Would the relay have somehow triggered the fuel injector code, or...what else could I have done?
#2
02-17-2011, 12:48 PM
It sounds like the throttle position switch is not set properly. Your car should have LH2.4 and I only really know LH2.2, but I think that the sensor works the same. I have two other theories: the throttle plate stop it not set correctly or the base idle is not set properly. I'm leaning towards the throttle position sensor being out of calibration.
When the engine is out of gear (park or neutral) there is no load on the engine, so it will idle noticeably higher if the TPS is not set right. It's function is to tell when the throttle plate is closed, so the car goes to the idle program. There should be a little click when the throttle shuts and right when it starts to open. If not, loosen the two allen head screw that hold it in place and twist it until a click is just heard when it closes. Another thing that you can do is when it is idling high, loosen it and twist it. When the switch closes, it should idle normally. You can also check with a multimeter to see if the switch is making contact. There are 3 prongs in the connector. One ground, one idle signal and also a wide open throttle position position contact. You should be able to figure out which is which with a multimeter. I think the center one is the ground.
Swiftjustice did a whole nice write up on that here: https://volvoforums.com/forum/showth...tle+body+swift
When the engine is out of gear (park or neutral) there is no load on the engine, so it will idle noticeably higher if the TPS is not set right. It's function is to tell when the throttle plate is closed, so the car goes to the idle program. There should be a little click when the throttle shuts and right when it starts to open. If not, loosen the two allen head screw that hold it in place and twist it until a click is just heard when it closes. Another thing that you can do is when it is idling high, loosen it and twist it. When the switch closes, it should idle normally. You can also check with a multimeter to see if the switch is making contact. There are 3 prongs in the connector. One ground, one idle signal and also a wide open throttle position position contact. You should be able to figure out which is which with a multimeter. I think the center one is the ground.
Swiftjustice did a whole nice write up on that here: https://volvoforums.com/forum/showth...tle+body+swift
#3
11-06-2023, 09:52 PM
High idle on P and N
It sounds like the throttle position switch is not set properly. Your car should have LH2.4 and I only really know LH2.2, but I think that the sensor works the same. I have two other theories: the throttle plate stop it not set correctly or the base idle is not set properly. I'm leaning towards the throttle position sensor being out of calibration.
When the engine is out of gear (park or neutral) there is no load on the engine, so it will idle noticeably higher if the TPS is not set right. It's function is to tell when the throttle plate is closed, so the car goes to the idle program. There should be a little click when the throttle shuts and right when it starts to open. If not, loosen the two allen head screw that hold it in place and twist it until a click is just heard when it closes. Another thing that you can do is when it is idling high, loosen it and twist it. When the switch closes, it should idle normally. You can also check with a multimeter to see if the switch is making contact. There are 3 prongs in the connector. One ground, one idle signal and also a wide open throttle position position contact. You should be able to figure out which is which with a multimeter. I think the center one is the ground.
Swiftjustice did a whole nice write up on that here: https://volvoforums.com/forum/showth...tle+body+swift
When the engine is out of gear (park or neutral) there is no load on the engine, so it will idle noticeably higher if the TPS is not set right. It's function is to tell when the throttle plate is closed, so the car goes to the idle program. There should be a little click when the throttle shuts and right when it starts to open. If not, loosen the two allen head screw that hold it in place and twist it until a click is just heard when it closes. Another thing that you can do is when it is idling high, loosen it and twist it. When the switch closes, it should idle normally. You can also check with a multimeter to see if the switch is making contact. There are 3 prongs in the connector. One ground, one idle signal and also a wide open throttle position position contact. You should be able to figure out which is which with a multimeter. I think the center one is the ground.
Swiftjustice did a whole nice write up on that here: https://volvoforums.com/forum/showth...tle+body+swift
1. loosen the allen head screws beside the TBS
2. twist the TBS until there's a click
3. then retighten and that should solve the high idle?
When you say "it closes" are you referring to the valve inside the TB?
Essentially I'm asking if I need to disassemble the TB to do this and or can I do it while it's attached? And should the car be on or off while adjusting?
Thanks so much,
WB
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