Have a few questions.

[clinton2003]

Alright lets start with my car.

 

Its a 1997 Subaru Legacy GT I picked up a couple years ago. I found out it has the wrong engine. From what i can tell it should have a 2.5 dohc engine.

 

From what i can tell is it has a 2.2 sohc. The ej22 is not there its worn off or was taken off.

 

So with that info i can start with my questions. Ha!

 

The engine has developed a knock and has been increasing in intensity gradually. I would like to swap to a 2.5 sohc vs the dual for the simplicity and it not being an interference engine and ease of plug maintenance etc.

 

With that how do i tell if i have my same ecu or if they swapped it.

 

Either way it seems like since going from sohc to sohc it should be relatively easy.

 

I would like to start open source tuning my suby but not exactly sure what is needed to talk to the ecu. Read/write changes. I think i would only need an obd2 to usb cable and software but not certain. I have some experience tuning but would like to refine it more with this car vs tinkering with my other car which is a whole lot more complex. (2012 mustang gt twin turbo, fun car)

 

Thanks in advance for the input.

[johnegg]

The engine has developed a knock and has been increasing in intensity gradually. I would like to swap to a 2.5 sohc vs the dual for the simplicity and it not being an interference engine and ease of plug maintenance etc.

you need to learn some of the basics.

there are NO ej25 sohc engins in the 90s.

and the ones from the 00s will only swap if you swpa the entire wire harness and computer.

not many people do this.

and the few that do usually do it for a turbo swap.

 

so the ej25 sohc is not an option.

the ej22 you have is probably still good.

the ''rod knock'' you hear may in fact be tensioner noise from the t-belt.

pull the driver side cam sprocket timing cover,

and look behind the center cover with a flash light.

 

you are looking for this tensioner:

 

http://i.ebayimg.com/00/s/MTUzWDMwNw==/$(KGrHqN,!isFC73tFvJKBQ5-zVTRDg~~60_35.JPG

 

it is the new style one piece tensioner.

it can get old and start to slap around making a noise like rod knock.

 

or buy a mechanics stethoscope and isolate the ''knock''.

if on the front of the engine, behind the timing cover,

it is not rod knock.

if it is near the center line of the engine it is rod knock.

rod knock will go away if you pull the plug wire for that cylinder.

 

so do some research.

 

rod knock in the ej22 engines is not impossible,

but it is pretty rare.

tensioner noise for both the ej22 and the ej25 is pretty common in 98 plus cars.

 

if you have the old style, 2 piece, tensioner piston with separate idler,

then the noise is not the tensioner.

the tensioner piston is the thin horizontal item above the smooth pulley idler on the water pump in the pic below.

 

http://www.vincentfurniture.com/photos/subaru/engineteardown/IMG_5597.JPG

 

i suggest you locate the cause of the noise.

and identify the year of your ej22.

pull the valve cover and look at the valve clearance adjuster.

if it has an adjustable screw and lock nut, it is a 97 - 98.

these engine are interference engines.

the 98 came with the new style one piece tensioner.

 

if there is no apparent valve adjusters,

then you probably have a 95 - 96 ej22 with HLAs, hydraulic lash adjusters.

these engines are non-interference.

 

ALL ej25 engines are interference.

 

the original ej25 engine was probably removed because it needed head gaskets.

they are known for blowing head gaskets.

the ej22 engine was installed because it is the most reliable engine subaru ever made.

easy to work on,

will take a lot of abuse and keep running,

and will not die until you drive it with out oil.

[clinton2003]

you need to learn some of the basics.

there are NO ej25 sohc engins in the 90s.

and the ones from the 00s will only swap if you swpa the entire wire harness and computer.

 

This is why im wondering about the ECU codes, since my car now has a SOHC and came with a DOHC is the computer just freaking out or did the guy do a computer/harness swap

 

not many people do this.

and the few that do usually do it for a turbo swap.

 

so the ej25 sohc is not an option.

 

Again, since i have the 2.2 SOHC engine, i figured keeping a SOHC engine in the car would be easier since i wouldnt have to swap anything but tune the ECU to a bigger displacement

 

the ej22 you have is probably still good.

the ''rod knock'' you hear may in fact be tensioner noise from the t-belt.

pull the driver side cam sprocket timing cover,

and look behind the center cover with a flash light.

 

you are looking for this tensioner:

 

http://i.ebayimg.com/00/s/MTUzWDMwNw==/$(KGrHqN,!isFC73tFvJKBQ5-zVTRDg~~60_35.JPG

 

it is the new style one piece tensioner.

it can get old and start to slap around making a noise like rod knock.

 

or buy a mechanics stethoscope and isolate the ''knock''.

 

I have one and will do that, i didnt think of it.

 

if on the front of the engine, behind the timing cover,

it is not rod knock.

if it is near the center line of the engine it is rod knock.

rod knock will go away if you pull the plug wire for that cylinder.

 

so do some research.

 

I have done quit a bit of searching. This is the first i have heard of the tensioner noise causing a "knocking" sound. I know that some of the subaru's have a knocking sound on cold start because of piston slap, and once warm it goes away. That does not fit my car's description. Although i will have to check out the tensioner

 

rod knock in the ej22 engines is not impossible,

but it is pretty rare.

tensioner noise for both the ej22 and the ej25 is pretty common in 98 plus cars.

 

if you have the old style, 2 piece, tensioner piston with separate idler,

then the noise is not the tensioner.

the tensioner piston is the thin horizontal item above the smooth pulley idler on the water pump in the pic below.

 

http://www.vincentfurniture.com/photos/subaru/engineteardown/IMG_5597.JPG

 

i suggest you locate the cause of the noise.

and identify the year of your ej22.

pull the valve cover and look at the valve clearance adjuster.

if it has an adjustable screw and lock nut, it is a 97 - 98.

these engine are interference engines.

the 98 came with the new style one piece tensioner.

 

if there is no apparent valve adjusters,

then you probably have a 95 - 96 ej22 with HLAs, hydraulic lash adjusters.

these engines are non-interference.

 

ALL ej25 engines are interference.

 

Good to know.

 

the original ej25 engine was probably removed because it needed head gaskets.

they are known for blowing head gaskets.

the ej22 engine was installed because it is the most reliable engine subaru ever made.

easy to work on,

will take a lot of abuse and keep running,

and will not die until you drive it with out oil.

 

This car was beaten to death. I had the header actually explode and i had to bend it back and weld it. then 2 days later the muffler actually fell off (weld from pipe to muffler failed totaly)

 

So before I owned it it's had a rough life.

 

So the reason i believe the engine is on its last leg is a few signs.

 

First the knock has gotten worse, much worse.

I now have hard time starting it sometimes in the morning (not all the time, seems warmer air it does better)

When i first start driving, it seems really low on power, as in non existent.(if punched actually slows down) takes about half mile of driving to get to where it will accelerate normally

 

Thanks for the reply and hope you can respond to mine.

[johnegg]

This is why im wondering about the ECU codes, since my car now has a SOHC and came with a DOHC is the computer just freaking out or did the guy do a computer/harness swap

the number of cams has NOTHING to do with how the computer reads the engine.

4 cylinders is 4 cylinders.

only one cam sprocket send info to the computer, for all suabru engines,.

these are simple engines.

 

Again, since i have the 2.2 SOHC engine, i figured keeping a SOHC engine in the car would be easier since i wouldnt have to swap anything but tune the ECU to a bigger displacement

engine - computer compatibility has nothing to with cams.

 

the ej22 and the ej25 of the 90s are absolutely compatible.

 

or buy a mechanics stethoscope and isolate the ''knock''.

 

I have one and will do that, i didnt think of it.

do this first.

this is primary!!!!!!!!

 

First the knock has gotten worse, much worse.

I now have hard time starting it sometimes in the morning (not all the time, seems warmer air it does better)

When i first start driving, it seems really low on power, as in non existent.(if punched actually slows down) takes about half mile of driving to get to where it will accelerate normally

all of the above could be explained by a weak t-belt tensioner, and the timing being off by a tooth or two.

use the stethoscope to locate the noise.

pull the timing covers for the cam sprockets and see if they match.

 

i can not guarantee that your issue is timing related.

but based on my knowledge of the ej22 engine.

it is MUCH MORE LIKELY to be a timing issue than a bad compression or some other deadly engine problem.

 

locate the noise.

this is very telling.

 

do nor over think it.

find the problem and then we can help fix it.

 

.