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High Idle when car has been running for a while Topic is solved

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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scot850
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Re: High Idle when car has been running for a while

Post by scot850 »

The cables do become worn and dry over the years. It could also have stretched somewhat and sticks when warm. You can get special tools to help lube cables. You may also find that:

a) There is a broken strand in the cable
b) The spring has become weak with age

or both.

I have never seen a throttle assembly rusted to that extent even up here in the land of salt in winter.

Neil.
2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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RickHaleParker
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Post by RickHaleParker »

lcc014 wrote: Mon Jul 13, 2020 6:04 pm I shut down the car and removed the throttle cable from the pulley, the gap immediately closed by the throttle plate spring.

My question about the electrical connector on the throttle cable. What is that electrical connector for ?
Adjust the cable.

Kickdown switch is on the throttle cable, at the firewall.
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

lcc014
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Post by lcc014 »

I will try to adjust the cable and test drive again.

Thanks,

Ching-Ho Cheng

lcc014
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Post by lcc014 »

Early this morning, I adjusted the cable a little bit (when the car was "cold") to close the gap seen between throttle valve spring and stopper. I tested drove the car in the afternoon; whenever, I came to stop in front of traffic light, the rpm dropped below the 850 a bit and went back up to 850. Overall, I had not seen the high idle when engine was "warm/hot" (or maybe I did not drive for long enough). When I got back home and put the car in Park (P), engine rpm stayed at about 1100 and didn't come down to 850. This was better than 1300 or higher. I popped the hood and looked at the gap. It still had a small gap. Then I wiggled the throttle cable, I could hear rpm came back down to 850 (verified from the speedometer in dashboard) and the gap disappeared totally.

Something wrong with the throttle cable when engine was hot. It felt like something was holding the cable that throttle valve couldn't close all the way when I let go the gas pedal. I also tried to step on the gas and rev. rpm to 4k. I could see the rpm came down slowly to between 1000 and 850, not down to 850.

One question, could the MCU/TCM control the gas pedal (hence the throttle cable) to increase the idle speed ? I am waiting for the new throttle cable now.

Thanks,

Ching-Ho Cheng

lcc014
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Post by lcc014 »

scot850 wrote: Mon Jul 13, 2020 7:27 pm The cables do become worn and dry over the years. It could also have stretched somewhat and sticks when warm. You can get special tools to help lube cables. You may also find that:

a) There is a broken strand in the cable
b) The spring has become weak with age

or both.

I have never seen a throttle assembly rusted to that extent even up here in the land of salt in winter.

Neil.
Neil,

Which spring you were referring to ? From you signature, you oldest Volvo was 1993 and was sold. My is 1995 NA with about 397400 miles, original engine. I am in Boston so we also have salt everywhere in winter.

Thanks,

Ching-Ho Cheng

scot850
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Post by scot850 »

There is a spring in the throttle cable assembly plastic wheel where the throttle cable wraps around:

viewtopic.php?t=10485

If you look at the picture on this thread you will see the black round part in the picture. The spring is inside there. If you turn the black wheel with no cable on it it should snap back.

I no longer have a 850, but the first year 98 V/S 70's use a similar set up as well. I did have the 93 and 97 850's.

I hear you on the salt and rust part.

Good luck!

Neil.
2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

lcc014
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Year and Model: 855, 1995
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Post by lcc014 »

scot850 wrote: Tue Jul 14, 2020 6:03 pm There is a spring in the throttle cable assembly plastic wheel where the throttle cable wraps around:

viewtopic.php?t=10485

If you look at the picture on this thread you will see the black round part in the picture. The spring is inside there. If you turn the black wheel with no cable on it it should snap back.

I no longer have a 850, but the first year 98 V/S 70's use a similar set up as well. I did have the 93 and 97 850's.

I hear you on the salt and rust part.

Good luck!

Neil.
Neil,

Thank you for clarification. That spring is inside the pulley and it is still very strong. I need to use quite a force to turn the pulley for unhooking or hooking the throttle cable end out of/into it.

Without the throttle cable hooked onto the pulley, I could turn the pulley and let go of it. I could hear the throttle body valve spring turning and hit the stopper. With the throttle cable hooked up, throttle valve spring was dragged down by the cable and did not hit the stopper.

Thanks,

Ching-Ho

scot850
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Post by scot850 »

Well at least one good piece of news.

So then back to the cable. I had an issue with a split strand with one throttle cable inside the outer sleeve near the engine end. I tried lubing it and it helped a little until I removed it and looked closer and found a broken strand.

Neil.
2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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RickHaleParker
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Post by RickHaleParker »

lcc014 wrote: Tue Jul 14, 2020 4:14 pm It felt like something was holding the cable that throttle valve couldn't close all the way when I let go the gas pedal.
Drag .... ?

1. Disconnect the throttle cable from the throttle body.
2. With a length of string, tie the throttle cable up so that the end is elevated.
3. Put a drop of 3-in-one oil on the elevated end. Let the drop of oil soak in.
4. Do about four more drops.
5. Let it sit long enough for the oil to work down the whole length of the cable.
6. Reconnect throttle cable.
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD. Yamaha V8 conversion
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.

lcc014
Posts: 163
Joined: Mon Jul 05, 2010 5:41 pm
Year and Model: 855, 1995
Location: Boston
Been thanked: 2 times

Post by lcc014 »

I will try to lube the cable with 3-in-1 oil today.

Thanks,

Ching-Ho Cheng

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