swapped a 2.5 for a 2.0 jap eng runs good until you connect the mas air flow sensor change it there times not the problem

Anthony Labarbera

Asked by Jan 13, 2015 at 10:21 PM about the 1999 Subaru Forester L

Question type: Maintenance & Repair

1999 forester 2.0 jap eng

5 Answers

Anthony Labarbera

sorry it kills the engine when mas air is plugged in


This is TOTALLY a guess.. but the wiring for the 2.0 may have been different compared to the 2.5, i.e. switched. You would have to compare wiring diagrams as I wouldn't go hacking wires. You could also check to see what the 2.0 used as far as MAF VAF / other. It could be inputting a huge fuel spike (or not enough) cutting off the car. All guesses ;) I'm assuming you have done a ton of research to do this swap. Have you checked with any of the forum(s)? The gurus on there will be of much better service than myself. Maybe Nick will have something for you. I wish you well. Please post here what you find.


While Im not an import expert, did you swap the computer when you did the swap? Seldom will a swap to a different type, ie size not need the appropriate computer. When the mass air is unplugged, it likely substitutes a fixed value from a table, and when you plug it in, the value it sees doesn't match what it expects. Like the other comment, the wiring pinout could be different too.

Anthony Labarbera

changed pullies as instructed and top intake and sensors long block should run the same


Are you supposed to change all the duct work or keep all your intake ducting from the 2.5? It's just like the long block 2.5's being compatible from.. 99-04?ish but that doesn't include intake mani and sensors, etc. It's been a long time since I've looked into those info bits. I would ask around on the forum as to whether you even need to change that over. If all you wanted to swap was the 2.0, that might be it - minus the pullies and whatever specific sensors on the long block. Good luck :)

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