|
700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
Information |
|
960 Rough IdleViews : 905 Replies : 10Users Viewing This Thread : |
|
Thread Tools | Display Modes |
Apr 12th, 2021, 20:12 | #1 |
Grumpy git born too late!
Last Online: Mar 20th, 2024 01:04
Join Date: Jul 2014
Location: Between Derby & Nottingham
|
960 Rough Idle
Hi All
After a winter of hibernation, my 960 is back on the road after replacing the front control arms and ball joints, a new set of boots on 17" alloys and a mini-service and all is good. However, it's developed a weird idling problem in the last week. When idling, the car is shaking slightly, almost as if there's a misfire and looking under the bonnet, the engine is oscillating. However, under normal driving, it runs perfectly fine and is smooth, although seems slightly down on power. Anyone have any ideas? Rooting around previous threads, a vacuum leak might be the culprit, however my OBD-II readout shows vacuum as normal (20 inHg idle, 26inHg off throttle and moving). When I had the clutch changed last year, my mechanic informed me the flywheel (dual mass!) was slightly scored, but it should be ok. Would this affect the idle so much to cause vibrations? Cheers
__________________
1997 965 2.5 SE Manual 1996 944 Classic 2.3 LPT - SOLD/BROKEN/SCRAPPED 1997 S90 3.0 - SOLD to doingitsideways 2021 Škoda Octavia Estate L iV PHEV (Company) |
Apr 13th, 2021, 01:39 | #2 |
Premier Member
Last Online: Today 23:24
Join Date: May 2012
Location: Lakenheath
|
Add 0.5L of synthetic ATF (i use Carlube ATF-U) to the engine oil, drive it for a few days then do a rest on the fuel ECU. Chances are the hydraulic tappets have become gummed and lazy during the inactivity and the piston rings the same.
The ATF will clean them both restoring compression and valve lift and revive dry oil seals throughout the engine.
__________________
Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ |
The Following 2 Users Say Thank You to Laird Scooby For This Useful Post: |
Apr 13th, 2021, 07:36 | #3 | |
Grumpy git born too late!
Last Online: Mar 20th, 2024 01:04
Join Date: Jul 2014
Location: Between Derby & Nottingham
|
Quote:
Cheers
__________________
1997 965 2.5 SE Manual 1996 944 Classic 2.3 LPT - SOLD/BROKEN/SCRAPPED 1997 S90 3.0 - SOLD to doingitsideways 2021 Škoda Octavia Estate L iV PHEV (Company) |
|
The Following User Says Thank You to jonnyf90 For This Useful Post: |
Apr 13th, 2021, 10:52 | #4 | |
Experienced Member
Last Online: Today 16:01
Join Date: Jun 2007
Location: L/H side
|
Quote:
Coils can go faulty as well causing a similar symptom ...
__________________
My comments are only based on my opinions and vast experience . |
|
The Following User Says Thank You to Clan For This Useful Post: |
Apr 13th, 2021, 10:57 | #5 |
VOC Member
Last Online: Apr 12th, 2024 13:08
Join Date: Aug 2006
Location: Hounslow West London
|
As Dave above says, it might just be that the hydraulic lifters are a bit sticky in which case what he recommends should help resolve the issue. On my 960 that I used for many years, I only ever used fully synthetic oil and, being thinner, resolved all my issues with valve lifter wear and being sticky when cold. More importantly, I would also take off the valve cover and carefully check all the connections from the wires that come from the two amplifiers (one on each side, down low, of the inlet manifold) and go to each spark plug ignition coil. These coils get warm in use and, over time, hardens the insulation close to the attachment clip on the top of the coil. It only hardens for about an inch or two but, with repeated coil removal for plug maintenance, this insulation peels or breaks off and the exposed copper wires, harden and begin to break. When I had ignition problems, I found I had to renew the wires to all 6 units, not the whole length back to the amplifiers, but for a few inches from the coil. After I had done that, all my ignition issues had gone and the engine never ran so well. So, I would check.
|
The Following User Says Thank You to mjk164 For This Useful Post: |
Apr 13th, 2021, 11:40 | #6 |
Grumpy git born too late!
Last Online: Mar 20th, 2024 01:04
Join Date: Jul 2014
Location: Between Derby & Nottingham
|
Thanks for suggestions Clan/mjk.
Wouldn't coil issues also affect normal driving as well though? Cheers
__________________
1997 965 2.5 SE Manual 1996 944 Classic 2.3 LPT - SOLD/BROKEN/SCRAPPED 1997 S90 3.0 - SOLD to doingitsideways 2021 Škoda Octavia Estate L iV PHEV (Company) |
The Following User Says Thank You to jonnyf90 For This Useful Post: |
Apr 13th, 2021, 12:19 | #7 | |
Premier Member
Last Online: Today 23:24
Join Date: May 2012
Location: Lakenheath
|
Quote:
However, if what i suspect is correct about the lifters etc from the hibernation then you should notice a difference after af ew days with the ATF in the engine. Then you will have a much better idea of what the engine is or isn't doing, often things like this are a simple fix so try that first, if nothing else it levels the playing field so there aren't compound faults (many with minor symptoms creating one bigger symptom not necessarily related to the minor ones) throwing out red herrings.
__________________
Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ |
|
The Following User Says Thank You to Laird Scooby For This Useful Post: |
Apr 13th, 2021, 12:19 | #8 |
VOC Member
Last Online: Apr 12th, 2024 13:08
Join Date: Aug 2006
Location: Hounslow West London
|
In my experience, not necessarily. It may show up as an occasional slight misfire but more noticeable when at tick over. It only takes a few screws to check.
|
The Following 2 Users Say Thank You to mjk164 For This Useful Post: |
Apr 20th, 2021, 23:42 | #9 | |
'Mature' Member
Last Online: Apr 23rd, 2024 21:16
Join Date: Aug 2006
Location: Newcastle upon Tyne
|
Quote:
Incidentally, like you I've only ever used fully synthetic (Mobil 0w-40) engine oil in my car, changed annually or every 5000 miles, and at 179000 miles I've never had hydraulic lifter issues. Thanks, Stan. |
|
The Following User Says Thank You to StanC For This Useful Post: |
Apr 21st, 2021, 07:04 | #10 |
VOC Member
Last Online: Apr 12th, 2024 13:08
Join Date: Aug 2006
Location: Hounslow West London
|
Hi Stan, I don't have my 960 now but it was 1993 2.9 and had 380k on the clock. The wire I use for nearly all regular car wiring is standard 8 amp single wire from Halfords (HEF721), available at least in red and black. On the coil units I soldered the new wire to the Lucar clips; with care you can use the original ones as they are Lucas and not the rubbish that comes from other countries. As I said earlier, you only need to replace an inch or 2 back from the clip which sees the heat and hardens the insulation. The quality of wires used in these Volvos is good and, if not in a "working" area i.e. wires that have to be handled regularly for maintenance like for spark plug access, if left undisturbed, will last for years. I connected the new short length of wires to the original with simple torpedo butt connectors and crimp pliers. There is sufficient black plastic harness covering to pull back over the repaired wires. I always take the opportunity to visually check the wires in and around the engine to ensure the securing clips are good and there are not touching "wear" areas. After sorting out these coil connections, that resolved all sorts of odd running issues. Good luck.
|
The Following 2 Users Say Thank You to mjk164 For This Useful Post: |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
|
|