Hello Everybody!

First time posting, long time reader LOL.
I have left the c7z world and entered the c6 base world (I know, a little backwards) but here is my long story short:

Recently found a 09 c6 base, manual, with 39k miles at an auction.

From what I can tell is the only mods are long tube headers with no cats and a tune (i'm assuming a tune because the check engine light isn't on for having no cats). It originally sounded like it had a cam, but now that a lot of sensors and maintenance has been completed the idle is much smoother and it doesn't sound like a cam.

When first got the car, it had codes for Clutch position sensor/switch, crankshaft position sensor, rear bank 02 sensor (it doesn't have cats nor do I believe there is even an second 02 sensor plugged in the h-pipe), large evap leak, and "low oil pressure" indicator on the dash as well as bad battery cables that a cert. vette tech thought was the main issue of the hesitation, rough idle, inconsistent rough starts, and runs super rich and back fires when I let off the gas.

He tested the oil pressure from the oil filter and it read 50 psi so he told me we'll be good to do the plugs, wires and oil pressure sensor by the firewall and that the oil pressure sensor was bad so I could drive it. I already did the Crank sensor, Clutch sensor and after he tightened and adjusted the battery cables, the car ran strong as hell. Rough idle improved and the car was very strong (in comparison of what it was from the first day). I was driving it 120 miles one way to work a few times a week and getting on her since it was literally running better each day I was driving it. More power than the day before and less hesitation in the 3-4500 rpm band.

I got it back into him for him to do the oil pressure sensor, plugs, wires, and new battery cables to fix the little hesitation left.

He did everything BUT when he replaced the oil pressure sensor, it wasn't reading more than what it was originally of 10psi. He took it back out and did a pressure test from the sensor location and got 10psi again...

So, 50 psi on the bottom, and 10psi on the top, runs so smooth and starts strong every time. When I start the car now, the oil pressure has been higher at start each day which is around 15 (it was never above 10) and when I get on it the pressure goes up (as it should, right?) but under low stress it goes back down to around 9psi after being warmed up and cruising on the highway and still runs very rich.

No smoke, no puddles in driveway, no oil anywhere leaking that we can see from up top or underneath.

Any thoughts????

Thanks,
Mike

 

Welcome to the forums! Mike . It seems odd you are getting low pressure on top, wonder if the sensor hole has restrictions, Roto Ruter maybe might have gunk in the oil passage maybe.

 

You could run an oil line from the bottom to the top sensor for a better reading,that would be an easy fix. Or splice the wires and move the sensor to the bottom oil galley. Or tear it down looking for an internal leak. lots of options.

 

I feel like that's the best suggestion i've heard just based on how well the car is running. No ticking, no lifter noise, just smooth engine idle and decent power amongst the power band. Would a sea foam flush be a good idea? Then put oil, new filter in. Let idle for 15 minutes and change oil again and check both filters for anything significant?

 

My tech said that he checked the hole and took a pick into it and he said it felt wide open before he put the first sensor in.

 

Do you know if the engine has had internal work? The fact you only have 10psi at the sensor is a scary thought. I`m getting the impression there could be a problem with the oil filter by-pass valve (you have good oil pressure there) Its` a short distance to the oil sensor. You might talk to your mechanic about the by-pass valve or maybe an internal oil leak maybe? 10psi on top end is scary it lubercates the whole engine.

 

I don't believe so. It originally sounded like it had a cam, but after all the improvements, it has a pretty regular idle now. I'm assuming stock. Does addressing the bypass valve a difficult job?

 

The by-pass valve is axcessed from the back of the block, behind the bellhousing, (not easy to get to) Low mileage is good, Using good oil and filter? That leves two things it could be by-pass valve or internal leaks. This is my opinion

 

Thank you! I'm forwarding this to my tech. I appreciate the suggestions. I'm not sure what oil and filter specifically but I did get it from the chevy dealership across the street. Do you have a suggestion of filter and oil?

 

If you use the oil and filter GM suggests you realy can`t go wrong. Everyone has their own opinion on oils and filters. The fact you don`t have 35-40psi at the oil sensor is concerning. I have seen oil diagrams, I will find them.