Jump to content

Engine surging after it warms up...undriveable


Recommended Posts

Good morning,

I'm helping a friend with his car.  The car was sitting for about 7 months due to a broken transmission.

I replaced the transmission and got the car running again. 

The car starts fine, but after it warms up, the engine starts surging up/down and it's undriveable.  Once the car cools down and we try again, the same process happens.

I also noticed that when placing the key to the ON position, the fans will run continuously. 

The car is a Subaru 98 2.5rs with a JDM EJ20 something swap from the older pre-200 STI.

Any help would be greatly appreciated.


Thank you.

Link to comment
Share on other sites

You log shows it has massive trigger errors once it gets warm.  I suspect this probably means the cam timing is out but it maybe something wiring related.  Can you warm the engine up until it starts surging then do a trigger scope (while still idling).  Here is a quick vid showing how to do the triggerscope:     https://1drv.ms/v/s!AiYbYlZQuRHPmieMTkwQDCXEb2LY

Link to comment
Share on other sites

That's what TAC said as well.  Attached is the trigger scope.  Just in case I replace the cam sensor with a known good one, issue is still there.

I would think that if it was a cam/crank sensor or wiring that it would do it right away?  Why is it that it only does it once its warmed up?

I also noticed that the fans are constantly running. Not sure if they have been rigged to do so.


Thank you.


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...