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Random misfire.

Help, Advice, Owners' Discussion and DIY Tutorials devoted to the second generation C70, S40 and V50 Volvos -- awkwardly model year 2004 ½ onwards -- plus where to go for advice and discussion on Volvo's sporty C30 Coupe powered by Volvo's ubiquitous inline 5-cylinder power plant.
Greenday694
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Greenday694

Random misfire.

Post by Greenday694 » Thu Jul 11, 2019 4:16 pm

Hello everybody. Volvo newbie here. My aunt bought a 2003 C70 convertible beginning of Last Summer. Never buy a convertible beginning of Summer , but she didn't listen. Paid top dollar. It is in good shape, new top, 130000 on the clock. First problem, antenna ring on the ignition switch. For preventive maintenance I did a complete timing belt water pump replacement. It was original. Ever since day one it would occasionally have random misfire, then all of a sudden clear up. Codes for random cylinder misfire and depending on which day, would have a code for one or two cylinders misfiring. Very rarely was it the same cylinders each day. 1 + 5. 2 + 5. 3 + 1. I replaced all five coils and plug. Seemed to help a little bit. But the problem still comes and goes. Sometimes when it will start misfiring the check engine light will blink. Later on I would check for codes , sometimes I would have misfire codes sometimes nothing. I've been a mechanic for over 40 years. This one has me stumped. The only thing I can think of is the ECU. Would really appreciate some help from anybody who has any suggestions at all. And if it is the ECU, does it have to be reprogrammed to the immobilizer? Thanks, Keith



projectsmorol
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projectsmorol

Re: Random misfire.

Post by projectsmorol » Sun Jul 28, 2019 7:58 am

I'm assuming you've checked fluids for contamination. ie oil in coolant and vice versa. I'd look to camshaft positioning sensors and solenoids. Then of course injectors.


2008 C30:
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Greenday694
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Greenday694

Re: Random misfire.

Post by Greenday694 » Sun Jul 28, 2019 5:04 pm

Thank you for your reply. I did check all fluids. Everything looks normal. I searched the Forum, and noticed quite a few people mentioning using genuine Volvo spark plugs. I put a set in, even though the Bosch plugs I removed looked fine. But to my surprise after a couple of days of driving it, it ran a lot better and only gave me a misfire code for cylinder 1. Still very random. Sometimes when I start it up it runs perfect other times it's running on 4 cylinders. Then eventually it will run on all 5 again. And at any given time driving down the road steady Cruise, coming to a stop and idling, and even when accelerating , it will start misfiring again for a minute or two. I have about a 40-minute drive to work. During that trip of stop-and-go and short highway driving it will run on 4 or 5 cylinders at least twice. Cold engine partway warmed up and up to full operating temperature doesn't seem to matter. Warm sunny day or raining doesn't matter. Taking it easy or spirited driving.
I will check the cam position sensor and the solenoid. But I would think that would throw a code?
Thanks, Keith



Greenday694
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Greenday694

Re: Random misfire.

Post by Greenday694 » Wed Jul 31, 2019 5:32 pm

Everything seems to check out fine. I even tried unplugging the solenoid. That led to a new code p0014. Camshaft position timing over Advanced or system performance Bank 1. Which something along those lines is to be expected, if the solenoid is actually working. The Miss is extremely random. I started it up before I was done work, and seem to be running on 4 cylinders immediately. Let it run for about 3 minutes, no change. Shut it off went back in to finish and clock out. Was back in the car literally 12 minutes later. Started it back up again and ran smooth as silk. Driving down the road about 60 miles per hour, I could feel it start missing, then 3 to 5 seconds later smooth. then it would start missing again. I'm starting to wonder if maybe the fuel pressure is low? And the ECU is trying to compensate?



Greenday694
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Greenday694

Re: Random misfire.

Post by Greenday694 » Sun Aug 11, 2019 6:03 pm

Unfortunately still getting random multiple cylinder misfires. Every cylinder except for number 4. I even tried swapping coil 4 with one of the other ones. Still cylinder 4 never has a misfire. 1 2 3 and 5 will have random misfires Within a half hour drive. The worst part is I don't get any other codes. Warm sunny day or torrential downpour doesn't make any difference. Bumpy road or smooth Road. Idling, steady Cruise, hard and light acceleration. When it's running smooth on all 5, there is nothing I can do to cause a misfire. Any ideas would be greatly appreciated



Cees Klumper
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Cees Klumper

Re: Random misfire.

Post by Cees Klumper » Mon Aug 12, 2019 12:03 am

Maybe it is the fuel injectors after all.
On mine I had a fault code that only went away after I removed, cleaned connectors and re-installed an electronics module in the passenger footwell (forget the proper name now), yours sounds like it could be poor electrical connections also. But how about checking whether the injectors themselves are ok, or whether they are getting signal when the engine is misfiring with one of those node testers.



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RickHaleParker
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Re: Random misfire.

Post by RickHaleParker » Mon Aug 12, 2019 1:19 am

Have you done a compression test?
Lifters getting good oil flow?
Coil Packs bolted down good with a clean connection. The bolt is one of the coil pack grounds.


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
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1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

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