6 ignition coils in 9 months- 2000 ob 2.5 mt!!! Please help

[SubieDrew]

I have a 2000 SUBARU OUTBACK 2.5 5MT with 157,778 MILES on it. I’ve owned it since it was new. In the last year I’ve had issues with misfiring (P0301, P0302… and P0420) and 6 repeated ignition coil failures (the original, 3 new coils and 2 used coils).

My mechanic (Subaru and Honda guy) has been good in sticking with the problems and repairing it without additional charges. Without going deep into repair costs, he has run out of solutions. I’m hoping that this may be something that is “easy” but just overlooked.

I’ve checked out AA1Car Auto Diagnosis Repair Help and all over this and other forums… looking for some more expert help. I’ve found great info, but no specific match to this repeated problem.

I have a used coil from a scrap yard that may or may not be good (I’ve checked resistance… but inconclusive). I’ve checked the Subaru plug wires (new May 2010, grey 7mm silicone). All have the same resistance about 8ohms (if I'm reading my analog multi meter correctly.)

New plugs were put in December. I assume NGK with correct gaps and they are still in good shape since my mechanic put them in after a several other coil failures. The car was running very well after they went in.

There is no oil leaking into the spark plug chambers. All seem to be dry, as are the wire boots.

Before I put this used coil on and possibly fry it I want to try to troubleshoot any other issues.

I suspect it may be something with Cyl#1 or an electrical short somewhere. It seems to be related to colder temperatures but not sure.

What would cause so much resistance or too much voltage to the coil for so many failures?

For a fairly complete wrap-up of the past year and what’s been happening when, please read the attachment for what has been done.

Thanks for your help.

[subiesailor]

Coil failure with subarus tend to be pretty rare. With that sort of thing you would probably save money by simply having the dealer take it and do a full check given it sounds more like an issue up stream which is causing the coil to fail. Your non subaru dealer is simply going to keep replacing the failed part or start replacing other parts till the issue stops. That tends to be more expensive and time consuming than just having the dealer find the issue and fix it.

[CNY_Dave]

Bad ground?
Is there a current limiting resistor somewhere in the circuit?
Is it just one of the 2 integrated coils or both?
Does the same one of the 2 always fail?

Dave

[SubieDrew]

Hi Subiesailor,
Thanks for the reply. Not sure if you had a chance to read the attachment with more detail.

I agree that is is something "upstream". The last coil that went in, a brand new subaru coil that was waranteed, died immediately after install.

I thought a dealer would give me more specific Subie help. Once towed to the dealer, it started smoking when they were diagnosing it. The dealer I took it to, said they would need to put a new coil in for $369, then they could diagnose it. I was hoping they could have a used or test coil to throw in there to give me a better idea of what's going on.

The dealer said the ECU was fine, but I'm not sure how they figured that out if it was misfiring so poorly and the coils was smoking.

Rather than pay them $200 to put in a $170 part that takes all of 5 mins. I had it towed away from the dealer to figure out my next steps. Because of where it broke down, it's sitting in my in-laws' garage right now so it's out of the weather, but not in my own garage or near my mechanic

The good thing with my guy is that he hasn't charged me any more to keep fixing it since he got the part warranted and also put a couple of used coils in. But as you have said it's just throwing parts at it with no permanent fix.

Any thoughts as to things I could check before putting a used coil on to get it running again? If I can get it running I might take it to another dealer.

Or next step a 2011 OB

[subiesailor]

DEALER - they fix it and have all the proper systems and electronic tools to diagnose it. Plus if they screw up its their dime not yours. It cost me $300 to have my VW faulty Coils replaced. Given its not the coil it could easily cost you WAY more screwing around with it vs having the dealer find the issue.

[SubieDrew]

Hi CNY_Dave,
Not sure about the resistor. I know on other cars there's a fuse usually which would prevent over voltage to the coil. But I don't believe there is one on the OB.

It's always the front coil for Cyl1 +2. I think it may be something to do with cyl 1.. but that's only because the first coil the orig.. showed carbon tracking on the tower when the wire was taken off and the wire was bad.

[bstone]

Sounds like a bad ground, ignitor or ECU.

[SubieDrew]

Hey bstone -Yeah, that's what I'm thinking.

When I checked the 4 wire plug that goes into the coil, there seems to be conductivity to ground on those female plugs when I meter to the block. Does anyone know if that is correct?

I did see someone post about a problem they had with that 4 pin connector and it was a "simple" fix of the wires being re-set going into the connector.

I believe the ignitor is in the coil pack. So I would think that would rule that out.

Anyway to test the ECU? Or as subiesailor says- go to the dealer. The dealer said the ECU was sending good info to the coil, but I'm not convinced.

[ETC]

I havn't had to delve to deeply in to the coil on these cars, I sounds like you either have a ground issue or, a short in the harness/plug to the coilpack.

Other than that, I'm not sure what else could cause the part to keep shorting out ... I'm fairly sure you're right in thinking you havn't happened to get 6 bad packs ;]

Have you or the mechanic tried checking the plug for correct voltage and signal/ground while cranking the motor ?

Not sure what you meant about the resistance test being inconclusive, you should be able to check the primary and secondary resistance on these.

Here's a short thread about the coil [click the link in there for a coil test description] ... there's picture about what pins to test and the resistance lower down.

Coil Pack Testing

Also not sure what could be going wrong specifically on cyl #1, basically it's just the high voltage lead [plug wire] going there. Unless the plug was physically damaged somehow, I'm not sure how it could short out the coil.

Here's a pic of the internal working of the coil in case it gives you some idea of what's going wrong and what may be causing it.

[SubieDrew]

ETC,
Thanks a ton for the reply. BTW my 5 year old son loves your avitar. He saw it last week and still talks about it

One thing i did notice was that there didn't seem to be any dielectric grease on either end of the plug wires. How big of a difference will that make?

What's the test checking the plug for the correct voltage and signal/ground while cranking?

I'm not sure that my mechanic tested for the correct voltage and signal/ground, but the dealer I went to said the ECU was sending the right info to the coil pack. Since their diagnosis was basically everything I told them .... "the coils dead" and a list of unrelated issues I don't have high confidence in them or deep enough wallet. The car is currently about 40 miles from my home and my mechanic so I was hoping to get it running well enough to get to my guy or a dealer closer to home.

I did find that thread earlier. good stuff! I tested based on that thread using my analog multi meter (it goes from infinity, 1K down to 0 ohms.) so I would think it would work, but maybe I need to get a more precise digital meter. Here are my results-
Secondary side:
I get about 12ohms across the towers so that's good right?
Primary Side:
When I said inconclusive it was because when I read across the pins as in the diagram, no1- no2 and no2-no4 the needle doesn't move. So I was getting similar results as CO_97 in that last thread and he said his coils were seemingly working fine.

however if I test the other combinations (just for curiosity)
no1-no3 = ~2.25ohms
no3-no4 = ~60ohms
no2-no3 gives a slight needle movement to about 1K

As you said maybe I should just test it old school. Since most of the time a working coil runs fine when it's put in I might just give it a shot. I can always return the coil to the scrap yard if it's not working when I put it in...

I do have the complete FSM in pdf for this car so I guess I need to start tracking the wires from harness to harness, back to the ECU? But I'm not versed enough in checking much other than the basics of continuity.

Also the ignitor is all part of the coil pack in your diagram, right?
Thanks for all your help.