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I haven't been on here in forever but now I'm back. I got a 98 forester a couple weeks ago for $450 with a bad clutch. And upon setting up a tune up list I've noticed a few things with the car.

 

First of the engine is a transplant out of a legacy but this was done 100k miles ago.

 

My questions with the ignition coil set up are thus:

 

1. Why does this car being a 98 2.5 dohc have a coil that's for a 97 impreza 2.2 with plug wires for a 98 legacy 2.5?

 

2. Is there a way to convert over to the new 4 pin style ignition coils that are post '99+?

 

When looking on rock auto for part numbers and such it shows the replacement coil being the smaller diamond style with the 3 wire leads coming out of it with the female plug wire connections.

 

What I have is the 3 pin connector that clips onto the coil body itself and the male plug wire connections that require the 90° boots for the driver side of the coil (I forget cylinder numbers).

 

I know that the diamond style coil won't bolt up due to the size different and the obvious connector difference, so why is that listed as the correct swap?

 

Could the engine harness for the legacy have been used in place of the forester harness?

 

Sorry for the really long winded post but I've been searching all day today and part of last night and haven't found anything pertaining to this except one thread showing the differences in the coils I've mentioned.

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The 2.5 uses a different coil. But they are electrically the same. Dont sweat it much. It works. Coils after 1998 except legacy outback and GT models do not use an ignitor and the coils are electrically different.

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It's just odd that the coil on my car isn't what's listed online or even from subaru so I'm curious as to why ya know? I'm mainly looking to see if the possibility to go from the 3 pin to the 4 pin coil was there because my current coil had some pretty bad corrosion on the firewall side plug wire terminals enough to cause a rough idle, which after looking for plug wires l noticed the differences.

 

Not to mention I like to have everything "factory correct" unless I'm the one to purposely change something around. My 87 pathfinder is a prime example of that lol.

 

I guess the easiest way to find out is to hit up a u pull it yard and take pics and compare. My goal it to wrx swap this forester in a few years so this isn't a huge thing really. Mainly just curiosity taking hold.

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Well, a 2.2 in a forester isn't factory correct and the fact that everything fits means and parts books are often wrong. just don't get detailed. Make it work... You can use whatever coil you want for a 1995-1998 ej20-25 electrically. Possibly even older. You just need to swap connectors. Beyond that coils wont work.. The connector that clips onto the coil started in 1997. I dont know which year your looking at but it all seems plausible.

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4 pin coil is for Phase II engines. (W/O transitor/igniter)

 

Will not work.

 

someone probably swapped whole engine from 96/97 model.

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I'm starting to think they used the whole engine and harness too, it's a 2.5 dohc engine so I think the engine harness from the legacy was used in place of the foresters

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I'm starting to think they used the whole engine and harness too, it's a 2.5 dohc engine so I think the engine harness from the legacy was used in place of the foresters

 

Probably. 96-99 are compatible where the harness plugs into the chassis, but 98/99 use a difference coil pack and wires than 96/97

 

GD

Edited by GeneralDisorder

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Look on top of the block, behind/under the alternator. It'll say EJ2 something in the square.

 

Then look at the exhaust headers. Two ports on each side or a single port on each? That narrows down which year that engine is.

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It's an ej25d dual port engine

 

Look on top of the block, behind/under the alternator. It'll say EJ2 something in the square.

 

Then look at the exhaust headers. Two ports on each side or a single port on each? That narrows down which year that engine is.

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Someone put a 96/97 engine in your 98. This is super common with the 25D - they blow head gaskets and throw rods from being overheated. In stock form they were a problem and considered junk by many. To fix them (assuming the rods haven't been beaten out of them from overheating related detonation and oil breakdown), you swap the pistons for 2000-2004 pistons and use the 2008+ STI head gasket.

 

No - you can't use a 4 plug integrated-ignitor coil pack. That's a phase-II engine coil pack. 

 

GD

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Why swap to the 00 to 04 pistons? I'm guessing better design? And I'm assuming you mean the 08+ STI head gaskets because of design too? Are they better than the stock replacement gaskets (p/n 11044AA610)?

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Why swap to the 00 to 04 pistons? I'm guessing better design? And I'm assuming you mean the 08+ STI head gaskets because of design too? Are they better than the stock replacement gaskets (p/n 11044AA610)?

 

Better skirt design, but not the reason. They have a different compression height, and without them you can't use the head gasket. The newer gasket is 2/3 thinner and allows for greater cylinder wall rigidity to prevent fire ring failure. The 25D gasket is too thick and has the head too far away from the block - allowing cylinder wall movement and fire ring abrasion and eventual failure. You can't use this gasket without a piston change as the original pistons will physically hit the cylinder head at TDC. 

 

GD

Edited by GeneralDisorder

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Oh ok that makes sense. I have a feeling this engine has a head gasket issue because of bubbles in the coolant resovoir :/ right after start up you can squeeze the upper hose and it feels like it's pressurized. Plus when I first started it it was exactly at the full mark when cold after running it yesterday the level was about half an inch higher. Compression is good at 210 +/- 4psi on all 4 cylinders. When it's idling you can feel a dug dug dug to it and around 2000rpm it feels like it's misfiring a bit but that could also be from the old plug wires.

 

I just put a brand new radiator cap on it and it feels like it's holding pressure better than the old on and the upper hose doesn't feel empty anymore.

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Compression test won't show anything on these when the HG's fail. 

 

They pressurize the cooling system when the HG's fail. Bubbles in the overflow, etc. That's how they fail - combustion gassed into coolant. 

 

GD

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Since the new cap it's not bubbling anymore and the level in the resovoir is much more consistent. So hopefully it's fixed the issue but I'll be keeping an eye on everything once I start driving the car

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