Throttle sticking? or something else?
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From: Palo Alo, CA
Throttle sticking? or something else?
Hi All,
I noticed that the car is idling higher when at stop lights (around 1100-1300 rpm) but idles at about 700rpm when starting. When I put the car in neutral at the light (have an automatic), it jumps to 16-1800rpm. I hit the gas hard and it comes down most of time. Not sure if the throttle cable is bad or if its something else.
Saw this thread but not sure its the same thing. Any thoughts?
https://rennlist.com/forums/928-foru...i-believe.html
Thanks,
Ather
I noticed that the car is idling higher when at stop lights (around 1100-1300 rpm) but idles at about 700rpm when starting. When I put the car in neutral at the light (have an automatic), it jumps to 16-1800rpm. I hit the gas hard and it comes down most of time. Not sure if the throttle cable is bad or if its something else.
Saw this thread but not sure its the same thing. Any thoughts?
https://rennlist.com/forums/928-foru...i-believe.html
Thanks,
Ather
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From: Germany
If the throttle sticks, usually the cable between the throttle quadrant on the left side of the intake and the throttle is frayed just after the quadrant. When the rmp stays high, try to push the lever on the quadrant back to the rest position. Also feel for a break in the cable between the quadrant and the throttle.
Also move the lever a bit from and to the stop position and listen closely for a faint 'click' under the intake. Is it there?
Also move the lever a bit from and to the stop position and listen closely for a faint 'click' under the intake. Is it there?
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Joined: Dec 2010
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From: Palo Alo, CA
Hi Aryan, not sure I follow you. Where/what is the throttle quadrant? I see 3 cables, 1 is a thicker cable below the other two and is a little loose. There is about 2.5 inches of bare cable and it looks like in good condition on each of the cables. I sprayed WD40 on the cables and revved the throttle to move the cable in and out which made a slight difference but did not fix the issue completely. The engine is too loud for me to hear any clicking.
If the cable was sticking then why would it rev higher when I put it in park? It goes from 1100 up to 1800. Can't figure out why that would happen. Thx.
If the cable was sticking then why would it rev higher when I put it in park? It goes from 1100 up to 1800. Can't figure out why that would happen. Thx.
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From: Germany
^^^ That's the one.
However reading your post again, it appears you have a high idle after some driving. If the rpm jumps from 1100 to 1800 it doesn't sound like the cable though.
Other possibilities are:
Vacuum leak
How does the tranny shift? Any hard shifts? That would indicate a vacuum leak.
Sticking ISV
If you hit the gas hard and it comes down, this would indicate either the idle stabilizor valve (ISV) or the idle switch. The ISV is located under the intake and very hard to reach. It can stick if it is old. An easy trick to loossen it (but not always successful) is to disconnect the black hose that runs in front of the throttle quadrant with the engine running and spray some WD40 into the suction end (this with the engine running). If that doesn't work, the air filter and MAF needs to be removed and some tricky manouvering with a long straw is necessary to get the WD40 to the ISV. Don't do this yet, try the easy method first.
Malfunctioning idle switch
To hear the click of the idle switch the engine needs to be off. Just move the lever on the throttle quadrant a bit from and to the stop position and listen closely. No click means no idle signal.
Bad LH
Needs to be tested, repaired or replaced.
MAF out of whack
Needs to be tested, repaired or replaced.
However reading your post again, it appears you have a high idle after some driving. If the rpm jumps from 1100 to 1800 it doesn't sound like the cable though.
Other possibilities are:
Vacuum leak
How does the tranny shift? Any hard shifts? That would indicate a vacuum leak.
Sticking ISV
If you hit the gas hard and it comes down, this would indicate either the idle stabilizor valve (ISV) or the idle switch. The ISV is located under the intake and very hard to reach. It can stick if it is old. An easy trick to loossen it (but not always successful) is to disconnect the black hose that runs in front of the throttle quadrant with the engine running and spray some WD40 into the suction end (this with the engine running). If that doesn't work, the air filter and MAF needs to be removed and some tricky manouvering with a long straw is necessary to get the WD40 to the ISV. Don't do this yet, try the easy method first.
Malfunctioning idle switch
To hear the click of the idle switch the engine needs to be off. Just move the lever on the throttle quadrant a bit from and to the stop position and listen closely. No click means no idle signal.
Bad LH
Needs to be tested, repaired or replaced.
MAF out of whack
Needs to be tested, repaired or replaced.
Thread Starter
Instructor
Joined: Dec 2010
Posts: 186
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From: Palo Alo, CA
^^^ That's the one.
However reading your post again, it appears you have a high idle after some driving. If the rpm jumps from 1100 to 1800 it doesn't sound like the cable though.
Other possibilities are:
Vacuum leak
How does the tranny shift? Any hard shifts? That would indicate a vacuum leak.
Sticking ISV
If you hit the gas hard and it comes down, this would indicate either the idle stabilizor valve (ISV) or the idle switch. The ISV is located under the intake and very hard to reach. It can stick if it is old. An easy trick to loossen it (but not always successful) is to disconnect the black hose that runs in front of the throttle quadrant with the engine running and spray some WD40 into the suction end (this with the engine running). If that doesn't work, the air filter and MAF needs to be removed and some tricky manouvering with a long straw is necessary to get the WD40 to the ISV. Don't do this yet, try the easy method first.
Malfunctioning idle switch
To hear the click of the idle switch the engine needs to be off. Just move the lever on the throttle quadrant a bit from and to the stop position and listen closely. No click means no idle signal.
Bad LH
Needs to be tested, repaired or replaced.
MAF out of whack
Needs to be tested, repaired or replaced.
However reading your post again, it appears you have a high idle after some driving. If the rpm jumps from 1100 to 1800 it doesn't sound like the cable though.
Other possibilities are:
Vacuum leak
How does the tranny shift? Any hard shifts? That would indicate a vacuum leak.
Sticking ISV
If you hit the gas hard and it comes down, this would indicate either the idle stabilizor valve (ISV) or the idle switch. The ISV is located under the intake and very hard to reach. It can stick if it is old. An easy trick to loossen it (but not always successful) is to disconnect the black hose that runs in front of the throttle quadrant with the engine running and spray some WD40 into the suction end (this with the engine running). If that doesn't work, the air filter and MAF needs to be removed and some tricky manouvering with a long straw is necessary to get the WD40 to the ISV. Don't do this yet, try the easy method first.
Malfunctioning idle switch
To hear the click of the idle switch the engine needs to be off. Just move the lever on the throttle quadrant a bit from and to the stop position and listen closely. No click means no idle signal.
Bad LH
Needs to be tested, repaired or replaced.
MAF out of whack
Needs to be tested, repaired or replaced.
Thanks for the info guys.
Yeah, it shifts hard when it is running for a while. I also have a tranny fluid leak so I'm not sure if that is also causing that due to low fluid. I will take a look again after topping up the fluid. Sounds like I have a few things to check. Cheers,
Ather
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Joined: Dec 2010
Posts: 186
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From: Palo Alo, CA
Just a quick update.
I removed the MAF sensor, cleaned it with some solvent and also cleaned out the throttle body and it looks like the higher revving issue is solved.
Took it out to see how it performs and ended up with a speeding ticket for doing 108 mph on Hwy 280 in the bay area. I guess its fixed.
So I'm done with the fixes for now...
I removed the MAF sensor, cleaned it with some solvent and also cleaned out the throttle body and it looks like the higher revving issue is solved.
Took it out to see how it performs and ended up with a speeding ticket for doing 108 mph on Hwy 280 in the bay area. I guess its fixed.
So I'm done with the fixes for now...