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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Need help diagnosing engine running roughViews : 10750 Replies : 239Users Viewing This Thread : |
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Feb 14th, 2022, 17:02 | #1 |
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Need help diagnosing engine running rough
[YOUTUBE]https://youtu.be/1UhOnEHIB6s[/YOUTUBE]
https://youtu.be/1UhOnEHIB6s My car runs rough and vibrates a lot at idle and even more at 1500rpm. I've changed plugs, cleaned PCV, changed all filters, ran injector cleaner, etc. The car does have a crack both on front muffler and cat, but why would it only vibrate at idle and 1500? I'm suspecting a dirty MAF or distributor issues but i really dont know. What do you guys think? Seems worse when it rains and today the engine cut out in the morning while idling cold.
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Proud owner of a 1997 940 2.3 lpt Manual with 501,000km. Last edited by SalvadorP; Feb 14th, 2022 at 17:05. |
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Feb 14th, 2022, 20:41 | #2 |
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You'd be surprised how much a leaky exhaust can upset the running. Get that fixed before you dive headlong into firing the parts cannon at it or anything else for that matter!
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Feb 14th, 2022, 21:07 | #3 | |
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Quote:
Thx Dave. When i plugged the holes with putty both me and my partner noticed it was vibrating less. But the putty didn't hold at all. Vibration is back but could be coincidence. I'll do exhaust in the near future. Bit scared of not being able to undo the nuts. They look pretty stuck. Do you think it is worth disassembling distributor cap and cleaning it? Never did it in this car. Cheers Salvador
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Feb 14th, 2022, 21:17 | #4 |
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Yes definately clean the distributor, these do suffer a little hesitation from oil in the distributor, even in a fairly ok running car. Usually much smoother when changing to distributorless ignition.
I can't hear anything in the video, just voice. Stop the parts canon, start diagnsotics. Buy some spark checker lights (£20) and see if its noticeably different. Run the car in the dark without any lights (DRLs or spark checkers) and look for glowing around the HT system. |
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Feb 14th, 2022, 21:50 | #5 | |
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I didn't even know you could change the ignition system. My first car, an Opel, would act up everytime it rained because humidity got into the distributor. Got progressively worse until distributor was changed Is it easy to clean on the 940? Anything I should be mindful of? Like any part prone to break or hard to disassemble?
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Feb 14th, 2022, 22:00 | #6 | |
Go redblock or go home
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Quote:
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Feb 14th, 2022, 22:14 | #7 |
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Should i buy those washers before i remove the cap to inspect it?
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Feb 14th, 2022, 22:16 | #8 |
Go redblock or go home
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Feb 14th, 2022, 22:29 | #9 | |
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Also sometimes trying to tighten while hot can help release the threads as long as immediately after trying to tighten you loosen. The dizzy cap is probably worth doing too but do the exhaust first as you won't know if there's any improvement with the exhaust leaking like a sieve!
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Feb 14th, 2022, 22:46 | #10 | |
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Quote:
https://blog.fcpeuro.com/how-to-repl...otor-and-seals
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