Just got my car running again after being at the mech. Drove it home, all was well, even running better than usual, but now, at idle, engine warm, the oil pressure is only at about 20 psi, whereas before the mech, it was never below 30 psi ever. I know there was gas in the oil at one point during it's stay at the mech. There may be some gas in the oil now, but not too much since I changed 4 quarts of it (left the filter on).

The car was at the mech for a rough-running poor driveability problem. I had to drive the car about 2 miles with about a pint of gas in the oil, before I changed it.

BTW, the idle is now at 700 warm, whereas before the mech, the idle was at 500 warm. I would think the higher idle would make the oil pressure higher, if anything. The car got a new ecm and a new prom, and new spark plugs, which I think would have absolutely no effect on the o p.

Why do you think my oil pressure is lower now ?? What could have happenned ?

Thanks


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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

hey, in ur sig. its says Charcoal Grey, is that the color of ur car?

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88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

 

Sure enuf, charcoal grey is the color.

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

The oil pressure is a problem all its own, but the idle can be pretty easy to solve. Drive the car for about twenty minutes after it has warmed completely and entered closed loop mode. As this happens, the ECM will enable integrator function to rewrite the BLM tables specific to your engine/car. Until that happens, the engine will operate on the "Lookup Tables" for all engine control parameters. The operation should normalize after a day of driving under various speeds and load conditions.

The oil pressure, as stated, is a different issue. A mechanical gauge would verify what the dash instrument is telling you. Once you know the true pressure, you can determine what, if anything, should be done.

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Later,
Vader
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"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

did the mechanic change the oil? if so he might have put in a lighter weight oil your car then it had in previously. in my car an 88' IROC it had 5w30 oil in it and the oil pressure was low at idle about 20PSI at operating temperture. i replaced that oil with 20w50 oil and my pressure is now at 40PSI at idle and at operating temperture. that's what i tried and my results. as always stock gauges are prone to be inaccurate. As Vader stated use a mechanical gauge to verify actual pressure if in doubt. hope this helps a little.

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88' IROC-Z, 350 TPI, 700-R4

 

The mech added 1 quart only.
Wow, I am surprised that just changing your oil weight affected the oil pressure so much.
I know the sending unit might be faulty, but why would it decide to sudenly go bad now, just because I took the car to the mech for something unrelated to oil pressure?

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

You left the original filter on??? CHANGE IT! And change your oil again. This is definitely a situation where you DON'T want to save a buck or two.

Gas is a SOLVENT! In fact, that was it's primary use in the early 1800s before the use of the internal combustion chamber. And it is raking havoc with your oil and all of it's protection properties.

If this had happened to my car, I think I would have gotten a couple of jugs of the cheapest oil to use and basically FLUSH my entire engine by changing, short run time, drain and change again.

 

OK, I changed ALL the oil, including the filter. I thought it was staying above 30 all the time, until I got the temp up to 220 at a few stoplights, when it went dowwwwwnn to about 20 psi, at idle. I just don't remember if it used to go lower than 30 last summer. At 200 or so, the pressure is at 30 psi. I use 10w-30. Is it normal to go down to 20 psi at idle when the temp is 220 ?




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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

20psi at idle at 220 is no problem. Get a 'real' guage(mechanical) and verify the pressure if you are absolutely worried.

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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, current red metallic paint. Lots of other stuff...
82camaro