Vanman

1991 4Runner 3vze, just turned 165,000 miles.

Before: About 1000 miles ago she started running a little rough (especially at idle). Brought it to the mechanic, and he said the plugs needed to be changed (old ones were about 3.5-4 years old). Nothing else was wrong (as far as this issue). Had oil changed at the same time.

The other day I noticed the oil pressure gauge indicating low, maybe a couple of needle widths below the low normal line (the first of the lines). It also ran VERY rough during this...sometimes the oil pressure even going lower. Oil level is fine. Doesn't seem to matter if the engine is at temp. or cold. It is a bit worse when first starting, whether first thing in the a.m. or just after a quick stop at a store.

Once I step on the gas, oil psi improves. Driving is fine, but obviously something is wrong, or will go wrong. Fuel or oil issue, both?

Any thoughts?

Thanks!

Vanman

No one??

pb4ugotobed

The stock oil pressure gauge isn't exactly scientific. If you want turely accurate oil presure readings, you'll need a mechanical oil pressure gauge. Autometer makes some nice ones.

HAving said that, when it's idling poorly, what is the tach at? I'd be guessing when it does this it is at about 500 RPM (which doesn't mean there's anything wrong with your oil pressure... As the engine spins slower, the oil pump spins slower, thus lowering pressure). And yes at 500rpm it will seem to sputter a bit...

camo31_10.50

do oil pumps just GO OUT....or are they gradual?

because if it's just randomly dropping pressure like that...that'd be where i'd look.

Vanman

That is when it happens, as the engine idles low, at 800 or so.

Funny thing is, it seems to have improved now over the last few days (both issues). So I am guessing it is an idle issue, or something similar.

Thanks for the replies...

T_F_E

What is your oil filter? If you do not have a filter with an anti drain back valve every start will be dry and it will not sound good.

It sounds like your rpm is just dropping to low check vacuum lines and such.

iselloil

Change the filter to a K&n or mobil and amsoil 10w40.
http://www.amsoil.com/storefront/amo.aspx

pb4ugotobed

Screw all that man, that's one expensive oil change. I use Toyota filters, and the quaker state 10w40 for $12 for a 5 qt jug at walmart every 2500 miles. 185k plus and still runs perfect.

But that really doesn't have anything to do with the price of tea in china... You don't have an oil pressure problem. You have an idle problem. When the idle is low, it's going to stumble, and the oil pressure is GOING to drop because the oil pump isn't spinning as fast as it should be...

First step, clean your throttle body out real well. Get all that carbon and crap outta there. Then make sure your plugs and wires, and dist cap are in good shape. If all that checks out ok, then I'd start checking out the Timing, or the EGR system, as those can cause weird low idle issues like that intermittantly.

And pay attention to WHEN it does it. When the engine's warmed up? When it's cold? When the engine's been run hard for a while? When the weather is warm/hot/cold? After a long highway cruise? After city driving? Only after you shut it off, like you run into a store for a few minutes, and restart it when it's still warm/hot? Does it last the whole key cycle (until you shut it off again) or can you run it up the street (revving it up enough for normal driving...3krpm or so) and then it is fine after that?

Without having the truck in front of me it's real difficult to tell you "this is what is wrong... replace _________ (fill in the blank)" but if you can make a rhyme or reason, or establish some sort of pattern as to exactly WHEN it does it, could make it a lot easier to at least give a good starting point for diagnosis.

pb4ugotobed

Besides, I've seen engines completely sieze because of claims like this

Normal and Severe Service - Up to 15,000 miles or one year, whichever comes first, or longer based on oil analysis.


I don't care if it's super oil made by the Toyota God himself, I ain't running NOTHING for 15,000 miles. That's a bunch of crap if oyu ask me

iselloil

Who pissed in your corn flakes this morning?

I never mentioned running for 15,000 miles.The manufacturer says you can.The 3.0 runs low on the gauge,I found a combintion that holds better viscosity and has improved oil pressure in my 4runner.So the combination works for me.
I've got one vehicle with 463,000 miles on it with amsoil,235,000 with mobil 1.It all works,pensoil,mobil,quaker state,buy what ever.

Vanman

Thanks for the replies...

I will keep a log of exactly when it happens. The problem is that is hasn't happened now for a bunch of days (??).

Bill