I have a 94 LT1 Z28 with 135000 miles on it. The car runs great out on the road and seems to hold good oil pressure out on the road.

It idles at about 900 RPMs in neutral and the oil pressure gage sets right above the red. But when I am drive in traffic with the car in gear and my foot on the brake the idle gets down to about 500 and the oil gage drops into the red. I think it might be an idling sensor or something. What do you guys think?

Mark

 

Hold your breath and your wallet.

Many higher mileage cars do this for a long time. Its probably slack in the bearings and everywhere. How much psi do you have on a cold start? cruising? When you get on it?

Also, the pickup may have fallen off. Do a search for this issue.

 

Yea something isnt right there, my car is at 170k and my oil gauge is right at 20 during warm idle.

 

The car holds a good oil pressure at cold start up. When you get on it the oil pressure comes up good.

Could it be the gauge sending unit? How can I check this?

Mark

 

500 is too low of an idle. Mine idles at 700 warm and in gear. But the stock tachs are known for being inaccurate as well as the oil pressure guage. Keep in mind the specs for an LT1 say 6 psi at idle is ok(near red)..a general rule of thumb is you should see 10 psi per 1000 rpm. First thing you should do is get some aftermarket guages before getting too alarmed and see if they read the same. Also try using a 40 weight oil and see if the pressure gets better...alot of 30 weight oils are borderline too thin for an lt1..like mobile 1.

 

It could be. From what I have been told, with heat and age they can give a false reading. Though I am not sure how to check it.
What oil weight are you using??

 

My stock dash gauge says 40 psi warmed up at idle, and like 60-70 psi on the gas.
My car has 100,000 miles on it.

 

My car is stock except Intake and exhuast and its usually right on the middle but when you beat on it it goes up alittle

 

I had a friends formula that ran just like that. Mine idles at 20 when warm and cruising around 45. Cold itll be close to 60psi.
Like said though, the stock guages are known to be off once in a while. I would hook up a guage myself and watch it. Might be able to catch a problem early if there is one.

 

My 1995 LT1 has 92k miles, noticeable cam bearing wear (cam change), no oil cooler, M1-302 big filter, M1 10-30 oil, and at operating temp with idle in gear at approximately 650 rpm , my oil pressure is 25 psi (per my gage). When I had the stock sized Fram filter, the oil pressure was 5 psi less. If you have the factory oil cooler, you can lose up to 10 psi through it, if it has the expected internal clogging. If you go to 40W oil, make sure it's 10w-40, as straight weight is too thick to give good lubrication at start up.

 

Give us actual numbers Mark.

I am 80 cold, 60+ on accel, 40 full warm idle