New 92 SS, idle and oil woes

[Melchior]

New here, just bought a legacy turbo (92 5 speed ss) to have a change from the DSM's i'm used to owning in the winter.

It was a bargain so It has some "issues". I've been reading as much as I can around here, but I have a "stupid" question.

The car idles low when it's warm (I define low as dipping under 500 rpm) When it does this the oil pressure light comes on which scares the crap out of me. It goes away if I give it even the slightest bit of throttle (going from 400 to 500 rpm will stop it)

Now, I've learned that this thing comes on shockingly low (like 2.5psi!) and I would think with that little pressure the engine would have stopped running a while ago, so I started troubleshooting it as if the pressure is fine but I'm going to get an oil gauge on it asap to verify this.

So, can the simple act of idling that low cause it to trigger normally?
Could it be electrical (Bad ground, not enough alt output?)

I plan on testing for what I can (Alt output, battery, etc...) but I'm 100% new to subarus and in the next few weeks am crazy busy so I figured I would just ask if this is normal or if that light being on means without a doubt that the oil pressure has tanked.

Thanks!

[gijonas]

how many miles on the car? I could see a high mileage car flashing the oil light at low rpm as being expected.Are the HLA's noisy?

[SLODRIVE]

A really low idle can easily trigger the "OIL" light, especially when the oil's hot. I wonder if your IAC valve is all gummed up.

[Apex3]

Have you checked your oil level? Stupid question, but since you didn't mention it...

[Melchior]

Thanks for the replies guys!

Yes, the first time the light flashed I pulled right over and checked it, and it was actually slight overfull by a quart or so (I suspect the seller wanted to make sure it didn't leak dry on my ride home or something, they knew it leaked quite a bit)

It has 252,000 km's on it, so it's not low mileage.

I will be cleaning the IAC tomorrow actually, I tend to do that on all the cars I own (I've owned a lot of early 90's Japanese, and not one of them has a perfect idle control system after 20 years without being cleaned!) Between that and a compression/leakdown I'll see where I stand.


I forgot to mention that the AC idle up works (thankfully) and if I leave it on, no low pressure light, even at 600 rpm or so.

What is normal spec for oil pressure at cold and warm idle on this engine? 10psi or so?

[Legacy777]

It's possible the screws holding the backing plate on the oil pump may be loose, which may be causing low oil pressure.

You can download the service manual from my server, which should have the info you need.

http://www.main.experiencetherave.com/s ... and_Elect/

[Melchior]

Thanks for hosting that, I downloaded a copy earlier.
I'll take a look at the pump when I do the leaks/timing job.
For now, got it through emissions (just needed a new cat/o2 sensor)

Like I said the low pressure light only comes on at really low rpm (less than 400) so I wouldn't be shocked if it's just because of the low idle, but it sounds like you're saying that even then it shouldn't be triggered?

[ericem]

Whats your location? km so im assuming Canada? Maybe you are reading the cluster wrong, the thick knotch right above the main one is 500rpm then the next is 750 THAN 1000. Is there alot of oil on the top of the motor as well? Might just need to replace the oil pressure sensor its like $10 and do a full tuneup make sure there are no vacuum/boost leaks.

[CFK]

Ha, that's funny. I bought this car !!!

When I did the timing and everything I took apart the oil pump and there was only 1 tight screw. Haven't put it on the road yet since im starting the TMIC install today, but after I was finished I took it for a rip and it still idled low.

I replaced the PVC, can't remember what a IAC is but I might just run some seafoam through the vacuum ports and see if that clears it up. Oh the check engine light just came on so I will take a look at that. It was a TPS in my old Legacy.

[DevC]

My idle has dipped down a few times over the last year and a bit I've owned mine and the light has come on in the process, no issues from it, and my car has 460,000kms.

My view on it is it just means your warning light and sensor are working haha.

[CFK]

I started to take off the IAC since I have most things off to do the TMIC. OMG !!! That thing is hard to get at, actually I gave up and am now drinking beer instead.

Seems like it would be easier if the turbo was removed and say like I had a TD04 and could just throw it in after. I think that would be ideal The signs just keep pointing to ripping thay damn VF11 out.

Dumping seafoam down it just seems so much easier , obviously not as thorough though. And I guess it would be a real b!tch if I re-installed everything and then it flashed the dreaded CODE 24

[Legacy777]

Yes, getting at the IAC valve sucks!