Misfire p0304 kicking my wagons ass Topic is solved

VolvoTiger · Post by **VolvoTiger** » 19 Jan 2024, 18:44

Hello all,
2002 VOLVO V70XC 205,xxx miles
Having issues with misfire on cylinder 4. Rough idle and stumbling and vibrating. Stalled several times on the way to work.
I just replaced all plugs and the coil on the 4th cylinder and still giving same code.
I replaced coil with OEM Volvo one
and 5 plugs with NGK copper ones gap at .028. I have oem Volvos on order should see next week.
Drives bit better and did not stalled but rough idle at lights and loss of power and weak acceleration.
Not sure what to do.
Ideally I hope to fix fast since its my daily and only ride at the moment.
I read other threads here and other forums for Volvos about this. I pray its not brunt valve on 4th cylinder
Any suggestions?

VolvoTiger · Post by **VolvoTiger** » 19 Jan 2024, 19:06

also what's best way to check the coil plug wire with volt meter. not to savy with one but got one

Post by **jonesg** » 19 Jan 2024, 19:30

I think it should be 5v.

Post by **Krons** » 19 Jan 2024, 20:09

In the rare case the replacement coil is bad…I’d swap the #4 coil to another cylinder and see if misfire moves with it.

Post by **volvolugnut** » 20 Jan 2024, 08:19

Do the coil swap to another cylinder as suggested above.
Remove your coil grounds and clean and retighten.
Compare the coil wire voltage of #4 with other cylinders that are working.
Check the resistance between the ground wire at the coil and a good ground elsewhere.
volvolugnut

VolvoTiger · Post by **VolvoTiger** » 20 Jan 2024, 18:58

Ok Thank you all for advices.

The coil plug harness into the ignition coil was back track just slightly that at first glance it looks connected. The connecting tabs are broken. I used a zip tie to secure it in place. Now fires smoothly and idle perfects. Also 5 new plugs and 1 new coil now with a spare that works.

VolvoTiger · Post by **VolvoTiger** » 20 Jan 2024, 19:01

Also ordered from ebay a pack of 5 ignition coil pig tail harness for like $15.00. So I can replace the old half broken one with a fresh new harness connector.

https://www.ebay.com/itm/264302296730?_ ... p_homepage

Post by **MoVolvos** » 20 Jan 2024, 20:36

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Have a 2002 V70 XC with 83K miles with the same exact issue. Hope it will be as simple as that.
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Post by **abscate** » 21 Jan 2024, 03:38

I’ve pinched coil on plug wiring a few times into the ground m6 bolts, which will make a misfire of course. Make sure all that wiring is lest of fasteners

Post by **MoVolvos** » 02 Mar 2024, 20:13

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Replaced all 5 injector with an inexpensive set of generics so I can have 4 good used ones for backup. Code is gone and car running exceptionally well.

Pulled the injector wires and tested the injector and connectors / plugs. All connectors / plugs have voltage and number 4 injector shows open circuit while others settled at 12.2 ohms. As long as they are all close it's fine.

To test the voltage at the connector turn the key to second position and measure. Do not start the vehicle or else you will be measuring pulse rather than steady voltage. You should have about the same voltage on all 5 connectors. Looking down at the connector while attached, the right side should be positive but I don't believe it matters while checking as most DMM are self correcting. Again, as long as the voltages are about the same the circuit should be good.
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5 Pcs Fuel Injectors for Volvo C70 S60 S70 V70 XC70 XC90 L5 2.4L 2.5L
https://a-premium.com/product/volvo-c70 ... SNF2NKPCeO
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