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Discussion Starter · #1 ·
I've looked at the date codes, and my ignition coils are manufactured from early 2013 (code is 13W052, which I understand to mean 2013, 5th week, 2nd day).

It's a 2006 V70R, I'm the 4th owner. I have service record from the PO (3rd owner) that tell me the car was at 157,000km (~97,500 miles) in 2015, and I'm up to 195,000km (~121,000 miles) now. So assuming these coils were installed the same year of manufacture, and average driver is 20,000km a year, at best these coils have seen about 78,000km (~48,500 miles). Should they really need replacement, or am I just throwing away money?


The issue I'm trying to resolve:
I get a power drop out when accelerating, around the 3500rpm mark, I'll get power back around 4500rpm, but I haven't pressed all the way up to max to see what else happens because I don't want to stress it right now.
I've just replaced my ignition coil harnessing, and put in fresh plugs. I used to have isolated misfires on cylinders 2 and 5, but now I have infrequent misfires on all cylinders (like 5 per cylinder over a 20-30min drive). I looked at the coils physically while they were out, I can post pics if that helps, but they all looked just fine, no boot cracks or anything like that. Couple spark wells were wet with oil, and plug 3 had managed to back out so it was totally sooted in there. :eek:
I've also replaced cracking hoses from turbo to intercooler.
I *think* this all started shortly after cleaning my MAF and TB, but I'm not positive. Could be unrelated...

Anyway, primary question here is if I'd be wasting money getting new coils and should be looking to the next items on my list, or if it's a worthwhile next step.

Thanks!
 

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Got a part number for the plugs you put in?

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In my experience, when coils go bad, they misfire like crazy so 5 misfires over a 20-30 min drive is unlikely coils IMO. Easiest way to rule them out is move to different cylinders and see if the misfires follow the coils or not. What did you use for the replacement harness?
 

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I've just replaced my ignition coil harnessing, and put in fresh plugs. I used to have isolated misfires on cylinders 2 and 5, but now I have infrequent misfires on all cylinders (like 5 per cylinder over a 20-30min drive).
If the shorter (wrong) spark plugs were used (fairly common, even from volvo dealers) I would imagine it would misfire like that. Thats why I asked about part numbers for the plugs.



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When you changed the plugs were any rusty like water had gotten into plug cavities? Coils get replaced in case where the real problem is only boots that got wet or cracked, aged etc. Several years back a friend who is a tech at a Ford dealer (ford V8s with COP are widely known worst offenders for coil problems) told me they never change coils, they replace the boots. I thought he was crazy but I have replaced boots many times when the coils were not original and misfires were the problem. Rockauto has them for under $5 each and has a listing for R models. NGK brand. 248K mile old coils get changed.
 

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Discussion Starter · #7 ·
Turns out, I remembered incorrectly on the misfires. This capture was from the drive I took recording, and it was only 15min long. Cylinders 1 and 4 certainly doing worse than others, so I'll do a fresh recording, and then swap em for a good back to back comparison to see where the misfires go.



Got a part number for the plugs you put in?
If the shorter (wrong) spark plugs were used (fairly common, even from volvo dealers) I would imagine it would misfire like that. Thats why I asked about part numbers for the plugs.
I got the plugs from my local parts guys rather than volvo (significantly better price), but I'm sure I got the correct Bosch plug and checked the gaps to spec. I looked around the for the paperwork and couldn't find it, I'll try to pull the plugs this weekend and have another look at things for how they're doing after running for a few thousand km's. I'll get the part number off the plugs, and confirm gaps so I can inform.


In my experience, when coils go bad, they misfire like crazy so 5 misfires over a 20-30 min drive is unlikely coils IMO. Easiest way to rule them out is move to different cylinders and see if the misfires follow the coils or not. What did you use for the replacement harness?
I hand built a new harness with love. I planned to put together a write up, but haven't found the time yet. So here are some photos of the glory.

Here's my old harness on the engine.


Side-by-side of the old and new on the bench before install.


New harness on the engine.


Some shots of the installation.




When you changed the plugs were any rusty like water had gotten into plug cavities? Coils get replaced in case where the real problem is only boots that got wet or cracked, aged etc. Several years back a friend who is a tech at a Ford dealer (ford V8s with COP are widely known worst offenders for coil problems) told me they never change coils, they replace the boots. I thought he was crazy but I have replaced boots many times when the coils were not original and misfires were the problem. Rockauto has them for under $5 each and has a listing for R models. NGK brand. 248K mile old coils get changed.
I didn't really see much of anything to indicate corrosion in there, but here are some photos of the spark wells.
1. Looks ok.
2. Pretty discoloured, had a touch of oil in there.
3. Sooted as mentioned earlier. This plug was loose to the touch when I got in there.
4. Quite oily in this one.
5. Slightly discoloured, and a touch of oil in there.



Here are the ignition coils and spark plugs that came out as well.



Questions:
Any conclusions from these photos?
What does the discolouration mean in the spark wells?
Does the oil in spark wells mean bad valve seals?
Any insight on the old spark plug conditions? 1 and 4 were pretty white... due to misfires?
 

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Discussion Starter · #8 ·
Couple other things I forgot to mention. I did clean the spark wells and coil boots best I could before putting in new plugs.

Cattlecar, thanks for the tip on boots, I think I may do that.

When I take the car out for a spin, while recording I'll get the power drop to happen and see if misfires go wild.

Anyone have other aspects I should monitor with vida?

Thanks!
 

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#3 wasn't tightened all the way...

All the plugs look warn, they should be changed every 25k. Did you replace with Volvo?

Oil in the plug holes is PCV (most likely, though you'd expect oil on the valve cover) or spark plug tube seals (less likely, ignore for now, there's like no oil in there)

Check the grounds on the new harness.
 

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Discussion Starter · #10 ·
@hounddogger, I have replaced the plugs, will get part numbers of what I put in shortly.

Is there a certain resistance the found path should be under? Ideally 0ohm I expect?

I've suspected I need to do pcv service, I get oil on the valve cover over time. Passes glove test though.
 

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Really nice pictures and great job on the harness.

When I was getting oil on the valve cover I did the PCV and it was still happening. Replacing the oil cap gasket resolved my issue...
 

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No clue what the resistance should be. Probably low. Also look at the ground from the engine to the chassis. And the ECM grounds on the fender.

May also be worth getting another coil and moving it around to see if it solves it.
 

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Discussion Starter · #13 ·
Well, it takes forever for me to get time to act on things, and then about as long to find time to post on the results...

Here was the plan I had laid out to follow:
1. Baseline car, drive it while recording on VIDA
a. Cylinder misfires
2. Move ignition coils (swap 1/5, swap 2/4), take vehicle out for a spin while capturing
a. Cylinder misfires
3. Verify ignition coil grounds are good, record ohmage
a. Coil harness to engine head
b. Engine to chassis ground
c. ECM grounds on fender
4. Photos of spark plugs / wells
5. Get plug part numbers and measure gaps

So, here are the result:

1. a. Cylinder misfires baseline


2. a. Cylinder misfires after coil swaps.
-I swapped 1 for 5, and 2 for 4. Left 3 where is was as a control.
-Seems that the largest offenders stayed with the cylinders (1 and 4), and didn't move with the coils.


3. Verify ignition coil grounds are good, record ohmage.
-Everything was 0 ohms. Coil connection to engine head. Engine head to chassis. Chassis grounds along the left and right of the hood look good and clean.

4. Photos of spark plugs / wells
-Spark wells look about as good as they did last time I was in there, no oil build ups, no sooting from a loose spark plug.
-Spark plugs themselves though (maybe 10k km's on these), looks like 1 and 4 are showing some white depositing on one side, this is similar to the original plugs that came out.
-Zoom in on 1 and 4 to examine, and 5 as a reference for one that looks good.


Here's the old spark plugs for reference, notice 1 and 4 also had strongest white depositing.


5. Get plug part numbers and measure gaps
-Part number info is FR7NI33 Germany 755, Bosch R6
-All plugs gaps were checked with feeler gauges, confirmed at 0.028" gaps on all 5 plugs
-Also counted the number of threads between old and new plug photos and they match up



Conclusions:
I don't think it's the coils or the plugs, likely something else at play...

Next steps I'm thinking:
1. Borescope the cylinders through the plugs holes and have a good initial look around in there to see how things are right now.
2. Compression test
3. Leak down test
4. Seafoam the system
5. Re-borescope the cylinders and see how much things have cleaned up
6. Record another drive while monitoring misfires


Any thoughts or advice?
 

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Anyway to check/track the fuel flow to each cylinder? 1 and 4 running lean? I'm a total VIDA noob, but check the fueling. Wonder if injectors need service. 1 and 4 still seem to have the highest misfire counts after swapping.
 

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Discussion Starter · #16 ·
Did you check for missfire in VIDA before changeing the harness?
I don't have a capture of it, but yes I recall the misfire distribution being similar before the ignition coil harness replacement.
 

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Discussion Starter · #17 ·
Anyway to check/track the fuel flow to each cylinder? 1 and 4 running lean? I'm a total VIDA noob, but check the fueling. Wonder if injectors need service. 1 and 4 still seem to have the highest misfire counts after swapping.
1 and 4 always seem to have had the highest misfire count. I will see what I can track in Vida.
 

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Discussion Starter · #18 ·
So this was the plan:
1. Borescope the cylinders through the plugs holes and have a good initial look around in there to see how things are right now.
2. Compression test
3. Leak down test
4. Seafoam the system
5. Re-borescope the cylinders and see how much things have cleaned up
6. Record another drive while monitoring misfires

Today I was able to do the compression test, and the results were... varied.

Here was my process:
1. Engine at operating temperature
2. Remove charge pipe over engine
3. Remove coil covers
4. Remove ignition coils
5. Remove spark plugs
6. Disable fuel pump (take out fuse #9 in engine bay)
7. Relieve fuel pressure off the fuel rail at schrader valve
8. Install compression tester by hand in a spark well
9. Push accelerator all the way down
10. Turn over engine 8-10 times
11. Check dry compression x2
12. Add 1/4 oz of SAE 30 oil to each cylinder via spark hole
13. Check wet compression x2

Here is one dry compression check on cylinder 3:

Dry Test: (2 per cylinder)
1. 140-142psi
2. 140-142psi
3. 122-130psi
4. 130psi
5. 140-142psi

Wet Test: (1/4 oz SAE 30 oil added)
1. 165psi
2. 153-161psi
3. 120-122psi
4. 148-150psi
5. 158-160psi

Double Wet: (a second 1/4 oz of SAE 30 oil)
3. 160psi, then 145psi

Turkey baster did the trick for a quick measure and shot of oil into the cylinder. Pardon the messy work bench.



Conclusions:
Certainly something appears to be amiss in there, though looks more like on cylinders 3 and 4, than on 1 and 4. Cylinder 3 was the one that had a large amount of sooting in the spark well previously because my plug wasn't seated properly so that's likely a factor.

I can't say with certainty what the state of things is in the cylinders until I get in with a scope, though I will say the little I can see through the spark hole looks pretty black and crudded up. I still hope to scope them before seafoaming so that I can get a good before/after. Hopefully that will help to regain some consistency across cylinders as well.

Once I had everything put back together, I fired up the engine and got a large plume of smoke out the back - I expect this was burning off the oil I added to the cylinders, so I wasn't too shocked. What did shock me was the smaller plume of smoke that came out of the engine bay while my hood was open. I turned off the engine, had a look around and couldn't find anything. When I started up the car again, there was no more smoke... does that indicate anything to anyone? Exhaust leak somewhere?

If anyone had feedback on these results so far, I'd certainly appreciate it!


While I was in there...
I also replaced my ignition coil boots and springs per cattlecar's previous suggestion.
Coils get replaced in case where the real problem is only boots that got wet or cracked, aged etc.
The boots essentially just slid off, and the spring would then twist off the coil. The originals looked fairly tarnished, almost bronze in colour, the new ones are nice and clean.


I used a bit of dielectric grease on the coil shaft to help slip the new boot on and seal against any moisture. The new spring just twisted right back onto the coil, you can see one installed here.


Full set of new boots installed.


Nice shiny springs.


Oh, I also put a little grease on the boot seals to the valve cover. Again, to keep moisture out.


I'll do another capture of misfires on the way into work tomorrow morning and see if anything has changed.
 

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I got rid of the stock coils, and went with IGN1A coils, with custom wires from yoshifab. the coils run 50-75 a pop and ignite 300hp+ per cylinder on pure methanol (6:1 AFR stoich value, nearly double the requirement of gasoline for a stoich mixture).

i run e85 on the stock turbo, lots of boost, no problems, no missfires.

that being said, you may have fuel delivery issues. injectors, clogged baskets, ect. a flowtest would help put things on track.
 

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Discussion Starter · #20 ·
Right now I'm not intending to stray from stock tune, so I don't think I'll have a need for an aftermarket oil solution like you described.

Drive in this morning was still the usual misfire distribution, high count on cylinder 1, followed by cylinder 4, and some scattered ones on the remaining cylinders. Tends to be most misfire happen on idle either at cold start before I get moving or while waiting at a light. When I'm at cruising speed they don't seem to occur.

Is that telling to anything?
 
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