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

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lcc014
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High Idle when car has been running for a while  Topic is solved

Post by lcc014 »

This problem happened in around late April when we had the stay home advisory. When car is "cold" idle is fine, in park or waiting for traffic light. Once the car is driven for a while - "hot", idle speed goes up above 1300 rpm in Park position and a bit over 1000 rpm while waiting for traffic light.

Initially, I cleaned the IAC and the valve inside was moving freely when I shake the IAC. I also cleaned the throttle body too, not too much black deposit around the front and back side of the throttle body valve. Test drove the car after cleaning, same issue.

Then I got a new IAC from Volvo dealer and installed it. Still the same idle issue when car is "hot".

My car is 1995 NA wagon, what could be the problem here to cause the high idle in Park or waiting for traffic light ?

Thanks,

Ching-Ho Cheng
Last edited by lcc014 on Thu Jun 18, 2020 5:00 am, edited 2 times in total.

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RickHaleParker
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Post by RickHaleParker »

Check for DTCs, Air leaks intake and exhaust, stuck/leaking EGR.
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 »

There is no CEL. I will check the DTC anyway. Exhaust manifold was replaced a while ago due to the flex elbow leak. EGR was replaced years ago when I did the PCV replacement. How to check air leaks in intake, exhaust and EGR valve ?

Thanks,

Ching-Ho Cheng

lcc014
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Post by lcc014 »

I checked DTC code and found one in A2: 233 (Idle Air Trim Exceeds Control Limits); A1 had no code (111). So any more suggestion to troubleshoot the issue ?

Thanks,

Ching-Ho Cheng

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misha
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Post by misha »

A6?
Being a '95 it should have Jetronic LH 3.2 management will can have 2 separate ecu(s),one for engine and the other for ignition.
Last edited by misha on Thu Jun 18, 2020 5:07 pm, edited 1 time in total.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

lcc014
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Joined: Mon Jul 05, 2010 5:41 pm
Year and Model: 855, 1995
Location: Boston
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Post by lcc014 »

I have not tried A6. I only know A1 and A2 are for engine and transmission. I will try A6 to see any DTC.

Thanks,

Ching-Ho Cheng

lcc014
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Post by lcc014 »

Just went out to check for A6 DTC. There was no code, meaning, no LED lighted up in A6 socket. I had tried 4 times, no LED light up. I could see the female connector inside A6 hole, but just no LED light up when compared with A1, A2, etc...

Thanks,

Ching-Ho Cheng

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RickHaleParker
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Post by RickHaleParker »

Volvo 850 modules and Flash codes. Smoke injection is the best leak detector. You can use starting fluid on the intake side of a running engine for leak detection. When a leak sucks in starting fluid you will hear the engine surge.
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.

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misha
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Post by misha »

Open up ecu box.
If it's Jetronic...it will have 2 ecu(s) in ecu box....for a car with manual transmission and 3 ecu(s)...for a car with automatic transmission.
That said...
-2 ecu for engine and ignition for a car with manual transmission
-3 ecu for engine,ignition and TCM(transmission control module) for car with automatic transmission.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

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 »

misha wrote: Fri Jun 19, 2020 1:16 am Open up ecu box.
If it's Jetronic...it will have 2 ecu(s) in ecu box....for a car with manual transmission and 3 ecu(s)...for a car with automatic transmission.
That said...
-2 ecu for engine and ignition for a car with manual transmission
-3 ecu for engine,ignition and TCM(transmission control module) for car with automatic transmission.
Thank you for the information. If it is not Jetronic then it will have 2 modules (Engine & TCM); is that correct ?

Thanks,

Ching-Ho Cheng

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