General: '55 S40 1.8: Throttle Potentiometer Faulty Signal...

[eric19371]

Originally Posted by Clan

As you have a throttle pedal fault code I would say it is the connector terminals on both the throttle pedal and the CEM under the glove box . They can "fret" over the years and loose their grip on the pins . The only specialist is the volvo dealer who has the experience of these particular codes for the last 10+ years and knows exactly what to do ... If it were me i would also replace the white signal wire from pedal to CEM as it disappears up behind the dash and could be damaged where you will never see it .

Can you please explain what you mean by 'fret' in regard to the connectors as it is a term that i am not familiar with and Google searches only seem to give me guitar references.

I have in the past with electrical connectors that were giving me issues, dismantled them, manipulated the connectors to close the gap, cleaned with contact cleaner and then reassembled. This has so far given me successful results. Would it work in this case?

[Clan]

Originally Posted by eric19371

Can you please explain what you mean by 'fret' in regard to the connectors as it is a term that i am not familiar with and Google searches only seem to give me guitar references.

I have in the past with electrical connectors that were giving me issues, dismantled them, manipulated the connectors to close the gap, cleaned with contact cleaner and then reassembled. This has so far given me successful results. Would it work in this case?

fretting is when the male and female terminal contact faces move slightly in relation to each other due to expansion and contraction as the terminals warm up and cool down each day , they do get fairly warm . the coating then wears off in a fine powder form and tarnishes acting as an insulator , also the female terminal spring tension reduces making the problem worse .
If you are going to go through all that trouble you describe without repairing it , It is best to fit the new repair terminals which volvo supply already crimped to a piece of wire , there are three qualities of female terminals, specify the gold plated ones ...

[eric19371]

So, two weeks ago I finally cleaned all the CEM connectors following a video on YouTube (link). All seemed good and on the first test drive idle and acceleration both appeared improved. My wife has been driving it daily since then and this morning I connected my code reader. For the first time as far as I can remember I got the 'no faults' message.*

[Clan]

Originally Posted by eric19371

So, two weeks ago I finally cleaned all the CEM connectors following a video on YouTube (link). All seemed good and on the first test drive idle and acceleration both appeared improved. My wife has been driving it daily since then and this morning I connected my code reader. For the first time as far as I can remember I got the 'no faults' message.*

The problem with these was the plug on the throttle body it was moving and wearing the terminals.. volvos fix was wrap some tape around the outside of the plug to ensure there is no movement when you wiggle the plug .

[coupelover]

Originally Posted by Clan

The problem with these was the plug on the throttle body it was moving and wearing the terminals.. volvos fix was wrap some tape around the outside of the plug to ensure there is no movement when you wiggle the plug .

Hello Clan. I've recently bought a C30 1.8 petrol from 2007 from my friend. It has 201500 km on it currently. He sold it to me because it also has the same intermittent stalling and stuttering issue. I've read this thread and can see that you are very competent with this issue.

So my friend has done alot to try and fix the issue. he changed all sensors, cleaned the terminals, changed sparkplugs, did a compression test, new throttle body, read it ofcourse, etc. he found a guide that said all the possible faults and he fixed them all except a couple of things. I spent my evening just cleaning the CEM like you suggested. I haven't driven it on the road however. My friend is adamant in thinking it needs a new ECU because it is bad. I'm on the fence about a new ECU and the flaps in the intake. he said they checked it and the flaps were still perfect so i have no idea what it might be. I also checked the connector for the throttle body cable. Am i correct in guessing it's the cable that connects to the front of the throttle body? if this is the right one, it did not move at all.

The issue is just like anyone discribes. it drives alright until you feel the power dropping and when you push the clutch, it stalls. then it takes a few seconds to start back up and it drives perfectly.

Does your knowledge help me any further in my search to fix this god forsaken car? it's fun to drive but that engine malfunction really kills my pleasure i have with it. thanks in advance friend.

[Clan]

Originally Posted by coupelover

Hello Clan. I've recently bought a C30 1.8 petrol from 2007 from my friend. It has 201500 km on it currently. He sold it to me because it also has the same intermittent stalling and stuttering issue. I've read this thread and can see that you are very competent with this issue.

So my friend has done alot to try and fix the issue. he changed all sensors, cleaned the terminals, changed sparkplugs, did a compression test, new throttle body, read it ofcourse, etc. he found a guide that said all the possible faults and he fixed them all except a couple of things. I spent my evening just cleaning the CEM like you suggested. I haven't driven it on the road however. My friend is adamant in thinking it needs a new ECU because it is bad. I'm on the fence about a new ECU and the flaps in the intake. he said they checked it and the flaps were still perfect so i have no idea what it might be. I also checked the connector for the throttle body cable. Am i correct in guessing it's the cable that connects to the front of the throttle body? if this is the right one, it did not move at all.

The issue is just like anyone discribes. it drives alright until you feel the power dropping and when you push the clutch, it stalls. then it takes a few seconds to start back up and it drives perfectly.

Does your knowledge help me any further in my search to fix this god forsaken car? it's fun to drive but that engine malfunction really kills my pleasure i have with it. thanks in advance friend.

The fix for the plastic terminal shell on the throttle body was to wrap a layer of felt tape around the outside of the shell, this would stop the terminals wearing with vibration. The fault needs diagnosing properly not using guesswork of course 👍 something that can only be done with the car in front of you .