-99 Volvo v70 2.5t No spark on 2 cylinders

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 04:17

i everyone! This is my first post on the forum. Im sorry if i post this in the wrong spot. I recently purschased a 1999 Volvo v70 2.5t with a misfire. I was getting a p0300 misfire code so my first thought was that a few coils or plugs went bad. I replaced all the plugs, replaced one coil aswell as swapped the coils around, but the issue didnt follow. I determined that im getting No spark from cylinder 2 and 3. I also determined that all injectors were working fine. I cant find any tips on how to diagnose this issue other than that it might be some controle modules inside the pcm. Before starting to rip into the computer i would like to check if there is any way to diagnose of maybe the wires running to the coils have shorted out somewhere. Or IF someone else has had this issue and what they did to solve it. Im sorry if my english isnt that great as i am from Sweden but i hope it is understandable.

Post by **abscate** » 07 Dec 2020, 04:23

Good morning eliotlm!

The coils on a 1999...the best year for Volvo’s....get 12Volts constant and are fired by grounding through the ECU.

Make sure the 10 mm head, M6 hex bolts are tight as they are also coil grounds. Try two new spark plugs in 2 and 3.

How does the wiring look for the coil plugs! Check them for green corrosion , too.

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 04:38

abscate wrote: 07 Dec 2020, 04:23 Good morning eliotlm!

The coils on a 1999...the best year for Volvo’s....get 12Volts constant and are fired by grounding through the ECU.

Make sure the 10 mm head, M6 hex bolts are tight as they are also coil grounds. Try two new spark plugs in 2 and 3.

How does the wiring look for the coil plugs! Check them for green corrosion , too.

Thanks for the quick answers! When i checked for spark I hade the coil removed with the plug in it, but do you mean that the mounting bolts for the coils are also grounds, i can check the spark plugs again but all plugs got replaced two days ago

Post by **scot850** » 07 Dec 2020, 11:15

Have you reversed the coil wires on the 2 cylinders?

Neil.

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 11:57

scot850 wrote: 07 Dec 2020, 11:15 Have you reversed the coil wires on the 2 cylinders?

Neil.

What do you mean by "reversed the coil wires"?

Post by **kallekula** » 07 Dec 2020, 12:18

Move coil to another cylinder and check if the code now points there instead.
I believe you have two dedicated 10mm screws for ground, make sure they are snug.

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 12:39

kallekula wrote: 07 Dec 2020, 12:18 Move coil to another cylinder and check if the code now points there instead.
I believe you have two dedicated 10mm screws for ground, make sure they are snug.

Unfortunately i've tried that with No luck, the issue Still persists on those two cylinders and the only code i was getting was a p0300 so no particular cylinder. I Will check the grounds again but i tried My best cleaning and sanding them

Post by **scot850** » 07 Dec 2020, 12:45

I think the guys kind of covered it. Basically had the wires for cylinder #2 somehow got onto #3 cylinder and vice versa was what I was suggesting. We recently had this issue with someone who had checked all the obvious things and eventually found he had reversed the wires on 2 cylinders.

Swapping the coil with the cable still connected to the other cylinder will not fix the issue. You would need to swap the cables over.

Neil.

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 12:56

scot850 wrote: 07 Dec 2020, 12:45 I think the guys kind of covered it. Basically had the wires for cylinder #2 somehow got onto #3 cylinder and vice versa was what I was suggesting. We recently had this issue with someone who had checked all the obvious things and eventually found he had reversed the wires on 2 cylinders.

Swapping the coil with the cable still connected to the other cylinder will not fix the issue. You would need to swap the cables over.

Neil.

I'll try to switch them, i read that thread previously and went to check but i dont think that the wires even be switched as they point in different directions aswell as the coils being quite far away from eachother, but if i am able to switch the plugs, shouldnt it Still spark but just mess Up the firing order?

Eliotlm · Post by **Eliotlm** » 07 Dec 2020, 12:59

scot850 wrote: 07 Dec 2020, 12:45 I think the guys kind of covered it. Basically had the wires for cylinder #2 somehow got onto #3 cylinder and vice versa was what I was suggesting. We recently had this issue with someone who had checked all the obvious things and eventually found he had reversed the wires on 2 cylinders.

Swapping the coil with the cable still connected to the other cylinder will not fix the issue. You would need to swap the cables over.

Neil.

Just to check that i understood correctly, you're saying that i should try switching the plug thats on the cylinder 2 coil to the cylinder 3 coil and vice versa?