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Heres to hoping. The only time I e ever had an engine redline all on its own was when the TPS went bad and at that I had to move the throttle before it would do it. If I let it idle it was fine, but the slightest touch on the gas pedal was enough to make it redline. Swapped TPS and it was cured, but any electronic component which fails properly (or unproperly) could cause the same reaction.

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  • 2 weeks later...

Well, put the "new" ECU in this morning. And we're still revving. Back to the drawing board. I have the old engine and all it's components, and a full EJ18 setup (same in a number of parts) Anyone have any other ideas on what I can try?

 

I have to think that a Vac leak, even a large one wouldn't just put me at redline right away would it? Even so, there's no good way to check while it's running with a spray can or something because the engine would run dangerously high.

 

Could I have missed something in swapping the injectors over? Also considering swapping the whole intake manifold over to see if that clears it up... I have to think this is a simple fix though.... if only I could figure out what it is.

Edited by AdventureSubaru
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Well, put the "new" ECU in this morning. And we're still revving. Back to the drawing board. I have the old engine and all it's components, and a full EJ18 setup (same in a number of parts) Anyone have any other ideas on what I can try?

 

Uhh....you did check that the throttle cable is not too tight?

 

Otheriwise, I'd say you have a leak at the intake manifold.

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Stumper for sure.

 

What about fuel pressure? I'm not sure if a stuck/ clogged pressure regulator would make it do that but if you have one to swap it only takes a few minutes.

 

Maybe that combined with a massive intake manifold leak? I would think it would have to be the manifold base gaskets or the fuel rail O-rings if that were the case. At this point it wouldn't hurt to pull the manifold and check the gaskets.

 

Still wondering if you ever got the TPS adjusted. The procedure for this style sensor looks much simpler than the later versions.

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Stumper for sure.

 

What about fuel pressure? I'm not sure if a stuck/ clogged pressure regulator would make it do that but if you have one to swap it only takes a few minutes.

 

Maybe that combined with a massive intake manifold leak? I would think it would have to be the manifold base gaskets or the fuel rail O-rings if that were the case. At this point it wouldn't hurt to pull the manifold and check the gaskets.

 

Still wondering if you ever got the TPS adjusted. The procedure for this style sensor looks much simpler than the later versions.

 

Fuel rail O-rings! I pulled one of the rails - no O-rings between the injectors and the engine. Swapping the rings from the old engine now. This should do it!:banana:

 

Also... I feel pretty silly for missing that when I swapped them over.:o

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yep. It's off and running. Feels like it could use a tune up. (sitting 3 years would do that.) So I'm going to give it some better plugs. Otherwise is running as it should.

 

Would the plugs from an EJ18 swap over to an EJ22? I got some good ones in my spare motor.

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If you change plugs, you want to run NGK-BKR5EGP or BKR6E11. Great plugs, decent price. EJ18 plugs might be the same length, but don't quote me on that. As long as they are the same length from the nut, down to the electrode, you are good. Don't want to put a hole in your pistons now that the motor runs good.

 

Amazing how a little o-ring can cause such an issue, eh?

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Fuel rail O-rings! I pulled one of the rails - no O-rings between the injectors and the engine. Swapping the rings from the old engine now. This should do it!:banana:

 

Also... I feel pretty silly for missing that when I swapped them over.:o

 

:lol: It was just a guess, I was still convinced it was the TPS!

Glad you found the source of the problem!

 

For plugs I run the NGK BKR6E11. NGK part# 2756. <-- The parts store will list this number. Too difficult for the average parts jockey to figure out the long part numbers I guess. :confused: But the other number is what's printed on the side of the plug.

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Don't mess with the theottle screw because that will mess up the TPS reading. Put some new plugs in it, run some Seafoam and some strong fuel system cleaner and drive it for a few days. The idle should adjust up on it's own as the ECU learns optimal fuel and spark curves.

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