Forum Issues Discuss any issues you are having with the forums here.

Volvo S80 Engine Idling Rough

  #1  
Old 01-15-2015, 08:42 PM
Junior Member
Thread Starter
Join Date: Jan 2015
Posts: 3
Default Volvo S80 Engine Idling Rough

Yesterday, my garage received a Volvo S80 which has run 340,000 km. The engine type is B5254T2. The transmission type is AW50/51. The user said that the engine idle was rough all the time.

Trouble diagnosis:
I started the car. The engine ran at rough idle. The running speed was about 1400r/min. Used Volvo Vida Dice 2013A to read the trouble code. It showed that something wrong with air throttle. I thought that there were some reasons for this trouble.

1) Air throttle was so dirty.
2) Air throttle was damaged.
3) The wire harnesses of air throttle had problems.
4) Engine ECM was damaged.

First, I took out the air throttle. It was so dirty. After cleaning, I used the diagnostic tool Volvo Vida Dice 2013A to read the trouble code. It still showed that air throttle had problems.

Then, I used multimeter to measure the resistance of air throttle.

#1-#2 was 1.4Ω ( the standard value is 1.2~3.5Ω)
#2-#3 was 1368Ω (the standard value is 1000~1500Ω)
#2-#6 About 820Ω when closing the air throttle. About 1580Ω when it opened completely.
#2-#5 About 1480Ω when closing the air throttle. About 500Ω when it opened completely.

They were all normal. So, the first two reasons can be deserted. I found out the circuit diagram from diagnostic tool. And I tested the wire harness. I wanted to know that whether the wire harnesses can work, which were between the plug of air throttle and engine control module. The results showed that six harnesses can work. It meant harnesses had no problems.

Then I used multimeter to measure the voltages of air throttle plug terminals. The results showed that the voltages were normal. So, I tested the wire harnesses of air throttle carefully. I found that the harnesses were twined by gummed tapes. I took out the tapes. And found that two harnesses were twined together. When the engine temperature got higher or the engine was shaking, the voltage of these two harnesses increased. It caused the signal difference. That was why engine ran at rough idle.

Trouble shooting:
I welded the two harnesses again. I started the car. It can run normally. Read the trouble code with car diagnostic tool Volvo Vida Dice 2013A. The air throttle had no troubles. So the trouble was figured out.

Article From:Volvo S80 Engine Idling Rough - OBD2 Software
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Brandy1
2001-2013 model year V70
1
11-24-2012 06:38 PM
Chart
Volvo C70
3
11-15-2008 12:26 PM
ariston
Volvo S40
17
06-29-2008 12:24 PM
KD3K1P
Volvo 850
2
03-11-2008 02:38 AM
DACouture
Volvo 260, 760 & 960
26
02-19-2007 10:57 PM


Thread Tools
Search this Thread
Quick Reply: Volvo S80 Engine Idling Rough


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.