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PV, 120 (Amazon), 1800 General Forum for the Volvo PV, 120 and 1800 cars |
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Misfiring B18Views : 1463 Replies : 15Users Viewing This Thread : |
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Aug 2nd, 2021, 13:15 | #11 |
arcturus
Last Online: Yesterday 07:17
Join Date: Mar 2006
Location: Sagres Portugal
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Ron,Long time no hear!Hope all OK with you.PV at 12 volts behaving faultlessly.Stay safe
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Aug 2nd, 2021, 14:14 | #12 | |
VOC Member
Last Online: Yesterday 14:29
Join Date: Jul 2006
Location: Chatham
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Quote:
If you have twin SU's wind the jets back up, count the flats and note that down. With the air filters off make sure that the jet tops look to be in the same position, just below the carb bridge. If not equal recheck that the nuts are fully up. If that seems to be the case. carefully lower the high jet to match the low one. That might be less than a flat. Wind them down 12-13 flats and test drive. If OK you can make small adjustments to the jet nuts but usually they are within 1 - 1 1/2 flat s of each other. Rarely less than 11 flats down unless you have the wrong needles. If you have access to a carb suction tool. loosen the shaft nuts and adjust until equal using the tick over screws. That should really be done first as long as the engine is running. Don't forget to tighten the clamp screw afterwards! Last edited by Derek UK; Aug 2nd, 2021 at 14:37. |
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Aug 2nd, 2021, 19:24 | #13 |
Master Member
Last Online: Apr 25th, 2024 13:36
Join Date: May 2017
Location: New Milford, Connecticut
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A comment from the peanut gallery.
"It can start fine and run for a short period and then, not always, misfire. It does not want to accelerate and is very hesitant and kangeroos down the road. Plugs changed so far. Cap looks quite new and can't see any issues with it. I have also cleaned out the fuel filter." So if we can assume that the car has recently been tuned up and has relatively new ignition components, and that the distributor points are clean and properly gapped, then to me, "kangeroos down the road" suggests condenser. I have absolutely no experience with the B18 engine and can't even remember if the condenser on my B16 is internal or external. But I've had many a misfire, and a condenser failure can be a "spitting misfire", kind of like an angry cat, with the car bucking down the road. If you have an inductive timing light, set it up as if you intend to time the car. Start the car and one by one attach the inductive pick up to each plug wire. Simply look at the light. If it is flashing evenly and smoothly on all 4 wires, then it is not the condenser. If it is flashing poorly on just one wire, then that is where you have the misfire. If it is flashing erratically on all four wires, then it most likely the condenser. You can confirm without removing the existing condenser by attaching a second condenser to the connecting post and grounding it against the body of the distributor. Just lay it there, trying to insure a good ground. If the car then runs smoothly, you have your diagnosis. Insofar as the coil is concerned, I agree with Arcturus that a failing coil can sometimes be diagnosed by touching it after it has run for a bit. If it is getting very hot, it is likely failing. A defective coil can also manifest itself as an intermittent failure, manifesting itself once the engine is hot, but running smoothly wnen the engine is cold. Good luck. Edit: I don't know if this will be relevant to your long term plans or if it will help, but I swapped out my coil for other reasons in post #235 here. 6 volt system. https://www.volvoforums.org.uk/showt...279014&page=24 Last edited by blueosprey90; Aug 2nd, 2021 at 19:32. |
Aug 3rd, 2021, 09:09 | #14 |
arcturus
Last Online: Yesterday 07:17
Join Date: Mar 2006
Location: Sagres Portugal
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Just to be clear a hot coil indicates an ignition problem,not necessarily a faulty coil. I experienced this with a broken center contact in the dizy cap.
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Aug 3rd, 2021, 11:46 | #15 | |
Experienced Member
Last Online: Yesterday 22:32
Join Date: Jun 2007
Location: L/H side
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Quote:
Make sure you have genuine volvo distributor cap , rotor arm and Spark Plugs and Contact points ... they can be guaranteed to be ok , other's can't ... condensers are high quality from new , if someone has fitted a cheap general one it might not be .
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Aug 3rd, 2021, 18:00 | #16 |
Junior Member
Last Online: Mar 28th, 2024 16:36
Join Date: Aug 2018
Location: Surrey
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For what it's worth, the symptoms sound very similar to a problem I had many years ago with an MGB. It had been serviced a day or two before and it had been running well until I'd driven somewhere and it was time to go home. It started fine and idled well but any attempt at acceleration led to spitting, mis-fires and the kangaroo-effect. I was lucky enough to be within walking-distance of a little car-spares place. I bought a new condenser, fitted it at the roadside and everything was fine again.
A week or so later I mentioned it to the mechanic who had serviced the car for me. He apologised. I wasn't the ony person with problems - he'd had a bad batch of condensers. |
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