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Thread ID: 102503 2009-08-21 07:10:00 Subaru Legacy auto problems Cuchulain (15188) PC World Chat
Post ID Timestamp Content User
803216 2009-08-21 13:01:00 Too much flawing it maybe? R2x1 (4628)
803217 2009-08-21 13:07:00 accelerators go right to the floor for a reason hueybot3000 (3646)
803218 2009-08-21 17:15:00 If anybody has a solution to this problem I would be most grateful . I own a 1991 Subaru Legacy Turbo Auto, which is experiencing intermitent loss of power under load? Sometimes cuts out at low revs, but easily starts again . The problem is not regular enough for my mechanic to easily diagnose the problem . It seems to have started just after I had a oil and filter replacement, which may have no bearing on the matter or not?

Ah! Terminology and semantics can create a lot of grief .

Let me ask some questions first .

1) you said
intermitent (sic) loss of power under load?
. . . what do you consider "load" - and is this throttle-on or maintaining cruise speed or during passing demands?

2) you said
Sometimes cuts out at low revs, but easily starts again
. . . is "cuts out" is this to the point that the engine actually dies or do you just feel it might die and you shut it off and restart it? Do you hear any backfiring in the exhaust when this happens or is the condition silent? It makes a big difference .

3) I need to know if other filters were also changed when the lubrication service was done . Fuel filter?

There's a possibility that an oil-pressure qualifier sensor has been damaged and the ECM sees that the oil pressure is incorrectly reported as unsafe and it shuts the engine off .

Is the CEL on? This should at least be an OBD-1 system, possibly even an OBD-2 system but I don't know what models and systems they sell to Upsidedown Land . Typically you are behind the curve by a few years in technology in your automobiles .

I doubt seriously that chasing the turbo or it's intercooler for a problem could manifest as total loss of power to the point that the engine stops .

Cooling systems and other accessories aren't usually culprits for an engine dying either .

Low voltage or an alternator putting out some AC ripple from the DC output can cause a lot of oddball symptoms . The maximum AC ripple that most ECMs can accept are lower than 0 . 013VAC on the DC line . More just confuses the ECM and the sensors .

Isuzus have a real trouble with almost- or slightly defective/bad alternators - ones that would run well in anything else, but cause fits in themselves . Subarus are in the same boat for needing current purity .

I'll be here intermittently all day today (I'm in Southern California) and will try to answer as soon or nearly as soon as I see your RSVP .
SurferJoe46 (51)
803219 2009-08-21 17:18:00 i cant even imagine how itd get a hole in it, maybe you fed it too much gravel

Holes in brass floats were the bane of their design . It happened all the time and that's why the carb manufacturers went to poly-foam floats with a thin skin of impervious plastic on them .

Carbs, however, don't exist on most anything with wheels any more and certainly NOT on a 1991 Subaru Legacy, which we also have here in the States .
SurferJoe46 (51)
803220 2009-08-21 17:26:00 Yeah you are right phil probably best to do plug it into a diagnostic machine and do a compression check first .

The ALDL (OBD1) and/or the OBD2 port will not perform a compression test . It will report a missing spark plug (P0300 codes) or some sensor problems, but as a mechanical quality-of-engine-test it really isn't designed for that .

Compression tests are still done the old fashioned way - with a compression gauge .

There ARE however tests for cylinder-by-cylinder balance or support tests that will quantitatively assure that a single cylinder is pulling it's own weight . If any cylinder is too far out of line, it should pop the CEL anyway .

Besides - compression cannot be an on-off thing and make an engine stall and at the same time allow it to run normally at other times . Hard starting and loss of across the board power from bad compression is possible, but it's not a light switch .
SurferJoe46 (51)
803221 2009-08-21 21:21:00 Never said do a compression test from diagnostic plug in.
I said: and do a compression test.
I always do a compression test (with gauge) and or a leak down test after a cursory glance of spark plugs, leads, throttle body, loose connector wires.
We are not behind the curve in technology here, the exact opposite in fact we are world leaders in innovation.
prefect (6291)
803222 2009-08-21 21:28:00 Have you had the battery disconnected recently? Another simple thing to check is the earth strap. plod (107)
803223 2009-08-21 22:40:00 We are not behind the curve in technology here, the exact opposite in fact we are world leaders in innovation.

Hmm - that's where all the world's duct tape goes.

I sent a CARE package of KoolAid, now you wanna have me send some duct tape too?
SurferJoe46 (51)
803224 2009-08-21 23:36:00 Another thing that's common on turbo cars is the spark plug gap is too wide. Drop it down to 1mm. This will more often than not fix what feels like a boost cut problem, assuming there's no problems with air leaks in the inlet system. It won't be the cause of the engine completely stopping. Check vacuum hoses for security & splits. Good luck with a compression test on those,, they are great fun to do, but that won't make it cut out under load either. Does it run smoothly at idle? Not running on 3 cyls? Phil B (648)
803225 2009-08-21 23:49:00 If this was a motorcycle I would check the small hole in the petrol cap was not blocked, thus stopping the flow of air to the tank.
If this happens the fault described occurs.
And yes I have met it quite a few times over the last 60 years.
But this is a car.
I don't know if the same fault can happen with cars.
Tom
Thomas01 (317)
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