need ideas on what to check - flat, high-end acceleration

[UberRoo]

Originally posted by Earthworm
Is there a way to test if the IRIS valve is in fact functional?

Disable it.

[Beav]

Lee,

I doubt that you could damage the cats by dropping them from a normal height. I do have to ask... when the trans was r&r'd is there any chance the engine was rotated backwards while unbolting the convertor, etc? If so the t-belt may have jumped a tooth or so. (never turn t-belted engines backwards, there is slack on the back side of the belt that the tensioner can't compensate for when spun backwards) Food for thought.

[lee]

thanks Beav,

It was only a drop from the height of some tall jackstands, but it was a guess.

I don't think I rotated it backwards, but (along the lines of your current signature) never can tell what some fool (like me) will do & then fail to remember.

[Beav]

If you did you wouldn't be the first. Funny thing about Subarus is that one cam can be off, the other on and result in a difficult to sort out situation.

[SVXRide]

Originally posted by Beav
If you did you wouldn't be the first. Funny thing about Subarus is that one cam can be off, the other on and result in a difficult to sort out situation.

Beav,
How would you sort this out? Sounds like you'd have one bank of cylinders with the right timing and the other bank a degree or two (?) off (advanced?). Would this even show up on a Select Monitor?
-Bill

[Beav]

I sincerely doubt that any scanner or monitor would pick up the problem, at least not as a verbatim code. Hard to say 'never' in any particular situation, but I think it would be safe to assume as there is no code so dedicated.

BTW, it would be more than one or two degrees. Divide 360 (degrees) by the number of teeth on the cam sprocket (and multiply that by two for degrees of crankshaft rotation - remember the crank spins twice the speed of the cam on a four cycle engine.)

It can happen, on any engine with a t-belt. On SOHC engines the cam be be off one tooth and run, usually a bit difficult to start, almost always with high speed power loss. With DOHC one, two, three or all four cams can be off - it depends on the design and number of banks/cams involved. On the 3.3 one cam on each bank is gear driven so either one bank or both can be off. It can be especially tricky to diagnose unless one is up against the wall diagnosing the problem and takes the time to remove the t-belt covers and actually checks the marks. A vacuum test at idle might be helpful by indicating abnormally low vacuum, but if only one bank is off the vacuum loss might not be as apparent as it would be with both banks out of time.

[SVXRide]

Originally posted by Beav
I sincerely doubt that any scanner or monitor would pick up the problem, at least not as a verbatim code. Hard to say 'never' in any particular situation, but I think it would be safe to assume as there is no code so dedicated.

BTW, it would be more than one or two degrees. Divide 360 (degrees) by the number of teeth on the cam sprocket (and multiply that by two for degrees of crankshaft rotation - remember the crank spins twice the speed of the cam on a four cycle engine.)

It can happen, on any engine with a t-belt. On SOHC engines the cam be be off one tooth and run, usually a bit difficult to start, almost always with high speed power loss. With DOHC one, two, three or all four cams can be off - it depends on the design and number of banks/cams involved. On the 3.3 one cam on each bank is gear driven so either one bank or both can be off. It can be especially tricky to diagnose unless one is up against the wall diagnosing the problem and takes the time to remove the t-belt covers and actually checks the marks. A vacuum test at idle might be helpful by indicating abnormally low vacuum, but if only one bank is off the vacuum loss might not be as apparent as it would be with both banks out of time.

Beav,
thanks for the detailed answer! Guess I'm still shifting my "engine sense" out of single cam, american V8 mode
-Bill

[lee]

Beav,

On reflection, I can say I did turn it backward, but only slightly a time or two. The amount turned would be to better line up the bolt holding the flexplate to the torque converter - maybe a half-inch movement at the TC/flexplate bolt location. Is that enough to worry the issue?

A couple of qualifications before I tear off the front end: Would I have heard the tensioner or belt slip? When I did the job it was in my garage, no engines running, no music etc - didn't hear anything. Also, the engine starts fine and seems to run fine (no cutting out) at my normal pace - don't get on it too often these days.

[Beav]

the symptoms could be caused by a multitude of things. I just offered that particular idea because I know you have probably checked the more common causes.

[Sonar]

The IRIS in in fact BOTH electrical AND vacuum controlled, you CAN manually engage/disengage the IRIS if you want.

A constant flat top-end could be caused by many things, and my
"check" order would be this:

-IRIS not operating
-Clogged exhaust (smashed catalytic converter)
-lean fuel condition
-Misaligned cam's
-and probably even more not so obvious things....


/Sonny

[want-a-fast-svx]

I asked this in my ongoing saga, how exactly would one check the iris? Is there way to check whether or not its functioning correctly??Thanks for any and al help.

[SVX-FF]

Originally posted by want-a-fast-svx
I asked this in my ongoing saga, how exactly would one check the iris? Is there way to check whether or not its functioning correctly??Thanks for any and al help.

Start here Checking the IRIS

Steve

[SVX-FF]

I had the t-belt jump a tooth last year. There was a little slop on the right side and when I did a hard acceration it jumped. The whole right side bank shut down. If the belt has jumped you would know. The car ran terrible.

Steve