is this normal

ok after my car reaches operating temp. when i pull up to a stop light my oil pressure falls what seems to be very low, around 20 or the mark right before the red lines. when i go to accelerate or when im moving everything is just fine pressure right at 60. is this normal or do i probably need a new oil pump and pickup. oh yeah and when my pressure drops it seems like my idle is a lil rough nothin drastic but it kinda feels like its sputterin a lil. and i have a 91 305 tbi. my idle might be rough though because i think i might need a new fuel filter and possibly a o2 sensor but any help would be great. and how hard would it be to change the pump by myself???

Quite possibly you could just need the O2 Sensor, but it might also be as simple as replacing the guage, you never know sometimes. The guage on my Buick goes up to 80 upon acceleration, and back down to 40 while cruising, i'm just to lazy to get it replaced. Fix the O2 sensor and i'm sure it will fix your idle problem though.

HA ! Ssssshit same thing happens to my 92. really pisses me off and freaks me out. Thing is..I bought my baby about 10 months ago and I took it in and had a lube flush about 3 months ago. Same day the problem started..I really don't like seeing the orange down in the red.

Like stated above , starts about 60 - 70 , drops to 40 , Hits 195 , goes down to about 10-20 oil psi area.

I'd imagine cleaning out the gunk would free up some flow and there would be less restriction MAYBE causing a small drop in pressure but I don't think it's suppose to be that way. It's quite scary seeing your oil pressure in the red when you're haulin 75mph+ and it should be about 45-50 ish.

I'm going to pull my oil pan off this weekend and tinker around inside probably do a new oil pump , new seals , Obviously new oil.

Ps - My engine only has about 40K on it.

PS-S - Would eliminating the PVC air valve that runs into the TBI Unit cause any sort of oil pressure drop and sticking a plug off or a breather on ? Let me know.

I have a 94 Z28 and my oil gauge does that too. I think its normal, I think the oil increases as your engine needs it, so when you rev, it will go up, and at idle, it may sit low.

It shouldn't be in red unless there is a problem.

you should snap a gauge on it. Stock gauges are known to read wrong because they are eletrical.

As long as you have the correct ammount of pressure when you are in the RPM's you should be fine. Really at idle, you would only need like 10 PSI min at idle. The reason that you need pressure at RPM is to keep the oil from being airrated.

you should snap a gauge on it. Stock gauges are known to read wrong because they are eletrical.



Stock guages are junk except for letting you know when there is a serious problem(except speedo). 90% of the time when people switch all the guages to a company like autometer they think something is wrong cause they get all new readings. The truth is quality guages are giving you an accurate reading unlike the stockers. So like Hypsi said if your really worried about something I'd go get an aftermarket guage for your readings.

I was thinking of getting the 3 pod set up , temp , oil , electric and cutting ecaxt fit holes in the face of my dash just above the console ( Stereo , a/c heater controls. ) You guys think that would fit ?

okay well then who sells a 3 guage pod i can mount somewhere in my car or do u guys have instructions for making one??? because i will probably get one for oil pressure water temp, and fuel pressure since i will be buyin an adjustable fuel pressure regulator

auto zone, checker and napa

HA ! PS-S - Would eliminating the PVC air valve that runs into the TBI Unit cause any sort of oil pressure drop and sticking a plug off or a breather on ? Let me know.

Edgar, the PVC valve is there for the reason of minimizing sludge buildup in your engine. The lifters "push" oil up through the rods (that's why they are hollow) to lubricate the rocker arms and springs. The action of all these moving parts under the valve cover plus the high engine (oil) temperature creates an oily mist or spray that would stick to all of these components. Therefore, in short order, creating sludge buildup. The PCV valve is connected to a vacuum port on the TBI or Carb to "pull" this mist to the intake, mixing it with fresh air and fuel, burning it in the combustion process. So, not only should the PCV valve stay put, it has an important function that does need to be checked and replaced when needed. To check while the engine is running , simply pull the PCV valve from the valve cover (leave the hose on the PCV valve) and place your finger over the bottom of the PCV valve. You SHOULD feel a vacuum. If you do not, replace it immediately. With the engine off, do the same but instead of checking for a vacuum, shake the PCV valve and you should feel and hear it "rattle" inside. A PCV valve is cheap and runs from $3-$7.00 at part stores.
A faulty PCV valve will also cause stalling, bucking and a rough idle as well.

O.o Well , I don't have any of that and I eliminated my PVC valves.

well, while i wont say ignore the oil guage, a good "shade tree mechanic" trick is that if you dont hear the engine makin alot of metalic tapping sounds, your oil pressure is probly fine. :evillol:

It's typical for the oil pressure to drop while you are at idle. Your oil pump is drivin by your cam and the faster you buzz the engine the more pressure you'll build up. As long as it's not in the red while you are cruising down the road you will be fine.

First of all John, a few basic questions to help all of us:
1) Did this just start all of a sudden or after something was altered or repaired? If you just bought the car was it already doing this?
2) Does the SES(service engine soon) light come on at all? If you are having a rough idle it could come on. With the OBD I(On Board Diagnosis) equipped cars the ECM (Electronic Control Module) could be having to compensate for an incorrect fuel/air mixture. The SES light would be a clue.
3) How is the oil pressure at idle when the engine is cold? And when accelerating while the engine is not yet hot?
4) How old and what viscosity is the oil? If you don't know because you just bought the car or it has been too long then a $20 oil change is cheap investment for a piece of mind.
Everyone that answers your question could be correct but any more details would help narrow it down. However, sometimes previous owners do some dirty deeds to sell a car. The SES light could be disconnected to hide a problem. Go to an Auto Parts store that has a FREE "Tool Loan Program". Tell them your car is outside and ask them to hook an OBD Scanner to the pod under the dash. If there is a code you will then be wiser. If you want to keep such a scanner around, then that's another $20-$40 investment. A shop will charge you more and...what will their diagnosis be?
So, take all of our advise with caution but the best thing to do BEFORE you begin troubleshooting with your wallet, let the Auto Parts store scan just to be safe. That doesn't cost a dime. Good luck and post any more details you can think of.

my 350 bearys the needle into 60 pounds while driving and idles at 30 pounds.

okay no its been doing it really since i got the car almost and i dont think its the pcv valve unless its a vaccum problem because i have already changed that when i bought it...and i just had my oil changed so its not that i use 10w30 quaker state deluxe (i like it because valvoline shit seems all watery to me) and when the engine is cold when i first start it my car idles higher till warm up so my oil pressure is fine...even if my car is just idling at 700 the pressure is fine its just when it warms up and my idle drops to around 500 that its a lil rough and no check engine lights i belive awhile ago i might have gotten an o2 sensor light but not since although i do have the part just havent replaced it yet and my tps sensor also needs replaced according to the ses light although it hasnt been acting up recently

okay no its been doing it really since i got the car almost and i dont think its the pcv valve unless its a vaccum problem because i have already changed that when i bought it...and i just had my oil changed so its not that i use 10w30 quaker state deluxe (i like it because valvoline shit seems all watery to me) and when the engine is cold when i first start it my car idles higher till warm up so my oil pressure is fine...even if my car is just idling at 700 the pressure is fine its just when it warms up and my idle drops to around 500 that its a lil rough and no check engine lights i belive awhile ago i might have gotten an o2 sensor light but not since although i do have the part just havent replaced it yet and my tps sensor also needs replaced according to the ses light although it hasnt been acting up recently

Well John, with what you are saying I guess that your car has quite a few miles on it. 20 psi at idle is still within the specs (I believe 18 psi @ 700rpm)for this car and, like "nvrenough" said, the oil pump is driven by the cam. So when the engine is at operating temp and the rpm's dip below the normal 700 the pump is also being turned slower than normal. Now, the more mileage on the engine, the more wear on all the internal bearings, rods (= more coverage area)and the likelyhood of oil return passages being clogged with sludge. All of these factors affect the oil pressure just as you stated. You might want to try Quaker State High Mileage oil, for engines over 75,000 miles.
Now, to the rough idle. This can actually be tough to pinpoint as well.
Since you already bought the O2 sensor and hopefully the special O2 sensor wrench also (it's worth it's weight in gold), I would install it as soon as possible. The O2 "tells" the ECM how to mix the air/fuel and if it's bugging out it sends the wrong ratios. If the ECM is getting false info from the O2 then the ECM might "think" the Throttle Position Sensor is bad as well. You've spent the money already so go that route first.
Unplug the power cable to the ECM after replacing the O2 sensor for at least 30 seconds. That will clear the memory which says you have or had any problems. If the SES light comes on again, get the code and go from there.
Another cheap (cheap<<<always good) trick to detect possible vacuum/intake/TBI leaks (which, of course, effects idle quality) is to let the engine idle. Carefully spray Carb-Throttle Body cleaner around the intake gaskets, vacuum hoses and the outside of the TBI. One area at a time. A short burst at the rear of the intake, wait for the engine to rev higher. If nothing, move on to the next area, covering all gaskets for the intake and TBI plus all vacuum hoses. If you find a spot that causes the engine to rev higher, mark it and continue until you have all areas covered. Then replace any vac hoses and/or gaskets.
There can always be other components that are causing these problems but before you go the expensive route of replacing ALL of the possible sensors, try the simplest and cheapest meathods first.
Good luck and keep us posted.

Waterman, very good points, and very in depth, i think ive slacked on this, but welcome to the forum, glad to have someone with your knowledge.

i have two suggestions however on what you said. To clear the codes on the ECM, i would suggest disconnecting the positive battery cable instead of the ECM power supply.

And also, while this is purley opinion, i avoid quaker state like the plague. Their additive is wax, and dunno bout the rest of ya, for some reason the idea of wax in my engine isnt something that sits well with me, but again thats just my view. I recomend switching to a lower viscosity oil, such as 10W-30 if you are currently using 5W-30.

When I had my engine flushed , they pulled a bit of gunk out , when I drove off from midas my oil pressure was like Holysh** it was at 80 from start up , idle around 45 and at about 190 F it was around 30+ for Idle.

Now , It's down in the red on idle. I think I will go with one of those Beaver high flo oil pumps . They are suppose to increase oil pressure over stock at idle and higher range. Anything OEM Sucks!!! XD

I ordered one and waiting for it , when I get that I am going to go through my car like a wild fire. Doing both door seals , hatch seal , re align my cowl hood ( Seems to have slipped. ) changing my 700R4 pan to a deep pan and a aftermarket filter / gasket set up. Changing my oil pan to a chrome oil pan with a eurathane seal , the oil pump , new u-joints , new rear end cover. It's going to be a chore...

Anywho back on topic. If the oil pump keeps it above 20 psi for Idle , I will recomend one of those. Just to be on the safer side , don't trust idiot guages. Get some aftermarket ones. Everything stock guage = Off by at least 2 numbers.

For instance : Bought a 2k4 Mazda 6 sedan. Cruising at 40 mph , went by one of those police radar thigs on the side of the road , said I was going 37 mph.

O.o Well , I don't have any of that and I eliminated my PVC valves.

It'sw a PCV valve, not a pvc. pvc is stuff you get at home depot.
Positive Crank case Ventalation.. Sorry thanks.

Did I put pvc ? whoops. I meant ABS!!!! Hahaha
Just kidding , no need to get all volitile over it. It was understood either way. Pvc is white crap and pcv is valve. But when some one says pvc for a car , we automatically assume pcv which is a little pos that sits atop of the valve covers. Either way , chill.

ok ill try those suggestions but no i dont have that tool to change the o2 sensor how much are they and what exactly are they called....and i do use 10w30 oil already i just like how quaker state deluxe is a lil thicker it seems to me valvoline resembles water too much

It's called a O2 sensor socket.almost any auto part store will have them and if they don't , they should! Thicker oil will give you more pressure but it's not exactly the best thing for your engine all the time. You need things to renew seals and keep them healthy instead of trying to run 20-50 through it Or is it 5-50 ? I dunno but one of my friends uses the thickest oil he can in his 6 cylinder and I dunno..seems like a power loss.

I ain't mad, didn't mean to offend you

Waterman, very good points, and very in depth, i think ive slacked on this, but welcome to the forum, glad to have someone with your knowledge.
i have two suggestions however on what you said. To clear the codes on the ECM, i would suggest disconnecting the positive battery cable instead of the ECM power supply.
And also, while this is purley opinion, i avoid quaker state like the plague. Their additive is wax, and dunno bout the rest of ya, for some reason the idea of wax in my engine isnt something that sits well with me, but again thats just my view. I recomend switching to a lower viscosity oil, such as 10W-30 if you are currently using 5W-30.

Thanx for the welcome Erik. I like the forum pretty much. I'll learn a lot here as well.

Now a word from Mr. Chemist a.k.a. Mr. S.M Artass
Is Quaker State grinding candles up and mixing them into the oil?
What you call “wax” is nothing more than Paraffin oil (used to make wax).
Paraffin, like ALL motor oils, is a distillate from crude oil. Household Mineral Oil that people ingest and use as a body lubricant, is paraffin oil. It's odorless and tasteless. Used in wax candles because it burns clean. Used in motor oils because of the same and it’s lubricating qualities.
Class dismissed. Have a nice day.
Oh, wait!
I recommended Quaker State because that was his preference.
I won't debate on taste or preferences. Everyone has their own.
As far as which power source to disconnect, to erase the ECM memory: Your choice of disconnecting the battery cable is by far the easiest, due to location. I always prefer the ECM’s cable because you don’t have to reprogram the stereo’s clock and programmed radio station’s. There might be some risk of arcing at the ECM’s pod and causing a “flash”. Deleting all stored info on the module but I have never heard of that happening. Removing the power at the battery is definitely ok with me.
Thanx again for the positive words, Tony