Google Answers Logo
View Question
Q: Interference Automobile Engines ( Answered 5 out of 5 stars,   1 Comment )
Subject: Interference Automobile Engines
Category: Miscellaneous
Asked by: charles44-ga
List Price: $2.50
Posted: 06 Aug 2002 20:17 PDT
Expires: 05 Sep 2002 20:17 PDT
Question ID: 51564
What does the"MFI/FI" stand for in the Subaru Engine Type: 2.2L H4
MFI/FI?  My understanding is that a limited number of "Interference"
1997 Legacy Sedan engines were produced for this particular year and
model.  I want to know if our car is one of these.  Thank you.
Subject: Re: Interference Automobile Engines
Answered By: alienintelligence-ga on 06 Aug 2002 23:53 PDT
Rated:5 out of 5 stars
Hi charles44,

MFI/FI stands for
Multiport Fuel Injection/
Fuel Injection [or Induction]
(I saw both noted)

For reference, the difference
between an interference and
a non-interference engine is
the clearance between the valves
and the pistons. In a non-
interference engine, if the 
timing belt were to break,
most likely all that would
have to be replaced is the
timing belt. In an interference
engine, if the belt goes, worst
case scenario are a bunch of
bent valves, or worse, dented
or broken pistons, and various
A picture that illustrates this:
[ ]
The pdf on that page listed no
DOHC or interference 2.2L's.

The 2.2L engine did come in both
versions a non-interference,
and an interference type. This
chart states that the SOHC (single
overhead cam) engine is the non
interference engine, and the
DOHC (dual overhead cam) engine
is the interference engine.
[ ]

Which of course makes sense if
you consider packing more than
2 valves in the small combustion

This page only refers to the SOHC
2.2L version.
[ ]

So does this one.
[ ]

[ ]

Refers in general to 2.2L being non-
[ ]

For the 98, the 2.2 and 2.5 are listed
as H4, but the 2.2 is SOHC and the 2.5
is DOHC.

The H4 is not the key to determining if 
it is interference or not. But I can tell
you for sure that if it's a DOHC 2.2L, then
it is the interference type. If you do
not know how to tell, feel free to reply
for a clarification with the VIN, and I
will be able to tell you.

-search technique-
legacy 2.2 H4 DOHC
[ :// ]
"2.2L H4" Subaru
[ :// ]


Request for Answer Clarification by charles44-ga on 07 Aug 2002 08:31 PDT
This is the first I've heard that a 1997 Subaru dual cam 2.2L engine
is really an "Interference Type", which of course, accounts for my car
having bent valves soon after a "maintenance timing belt replacement".
 For further clarification, I want to send you my VIN number, as you
recommended, but can I do this through a private email?

Clarification of Answer by alienintelligence-ga on 07 Aug 2002 12:31 PDT
Hello again charles44,

I'm on the phone with Subaru
right now regarding VIN decoding.
They don't know.

So I asked, is there a way
to tell any info about the
car in the VIN number. Ok,
remember this is THE SUBARU
of America Customer Service.
They said, no, there is no
way to tell any info about
the car from the VIN.

VIN decoding chart:
[ ]
No way to tell, hmmmmm. But
there is no cam info though.

You unfortunately cannot send
an email to me yet... can't
give out the email address here.
But from the VIN # it seems like
you can post it here, and change
the last 6 #'s to all 111111's maybe.
We won't know who you are then ;-)
I don't know if it would give any
info we don't know already though.

I am looking for a picture of your
engine right now also. 


Request for Answer Clarification by charles44-ga on 07 Aug 2002 14:53 PDT
Hi: I guess it makes no sense sending in the VIN number.  My mechanic
just told me that my 1997 Subaru 2.2L engine comes with 2 cams, but
only 1 cam shaft drives the valves.  Does this mean it's a single cam
or a double cam engine?

Clarification of Answer by alienintelligence-ga on 07 Aug 2002 16:44 PDT
Very interesting charles

Hmmm, well maybe I'm ignorant
on that particular Subaru engine,
but I don't know any car companies
that put on an "extra" camshaft just
for the heck of it. I think the
people at Subaru might have mentioned
it, considering I ended up talking
with 3 different service centers.

I just talked with a few of my
friends and they never heard of a 
dualcamshaft engine that had only
1 working for the valves. I say
since he said it was a DOHC engine
and the DOHC is a 16-valve, then 
the 16-valves makes it an interference
engine. And if it isn't... why are
the valves bent?

If he said it had 2 cams, then it's
DOHC. If both aren't OHC (in the head)
then I want a picture of the engine.

This isn't the Subaru service center
I hope?

charles44-ga rated this answer:5 out of 5 stars
I've been to many sources to help clarify whether my engine is an
"interference type" or an "non-interference type".  This is the only
information I've found that can account for my car's having bent
valves.  Thank you for this research.  I don't know why my mechanic
and dealer keep coming up with the wrong answer.

Subject: Re: Interference Automobile Engines
From: vrg3-ga on 13 Aug 2002 00:08 PDT
Your Legacy's 2.2 liter boxer four has a SOHC design. Your owner's
manual should be able to verify that.

Note, however, that this is a "twin cam" engine as there are two banks
of cylinders. Unlike most Japanese four-cylinder engines, which have
an inline configuration, Subaru's engines use a horizontally opposed
layout which places two cylinders in each bank. Each bank has a single
cam driving the valves.

Subaru's dual overhead cam engines are "quad cam" designs.

a reference:

I am almost certain your engine has a non-interference design, but I
do not have on hand a reliable source for that information. I believe
that in 1997 the EJ25 (the 2.5 liter) was an interference design and
the EJ22 (yours) was not.

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy