GK

On the 28th I got a check engine light when entering a freeway (accelerating). I pulled the code via Torque and it was for: P0300 - Powertrain Random/Multiple Cylinder Misfire Detected.

I did some Googling and found it could be anything from a loose plug cable, burned cable, bad plug, etc.

I did a get physical check of all the cables and everything appears to be ok. At least, to my eyes. Cleared the code and have had no issues.

Until today....

While driving the car home from work, a very noticeable knocking sound appeared just as I was approaching my exit. I let the car settle for a few and checked the oil levels, which looked good. Checked all the cables and whatnot that are under the fuel rail covers once again. Didn't see anything that was obviously scorched, burned, unplugged, etc.

Now, I don't recall what the normal Oil Pressure levels are supposed to be, but when I was running the car for this video, I noticed it was hovering around the 20~ area (visible in video). I am not 100% sure, but I feel like I was in the 40~ area beforehand.

Your thoughts?

Is the car even safely drivable? Do I have some serious damage on hand?

ssrallyred

20 psi of pressure is not good and that sound is not normal, sounds like a rod knock from the video and yes around 35 min-40 psi is normal at warm/hot idle. A miss fire code can be set by the crank sensor when it detects an abnormal ignition firing, which will happen with a spun rod bearing. Time to rock a new setup my friend !

GK

Thank you for your response.

When you say new setup, which components are you referring to?

I'm thinking of driving it to the mechanics about 2 miles away to have it checked out.

callie454

Pull the valve covers and check for a broken valve spring.

vpshockwave

When my car was stock, my oil pressure while idle when warmed up hovered around 29-33 psi I think. I never hit 40 PSI unless it was cold or I was driving it. Now that it's cammed/tuned it idles right at 40 psi. But 20 seems way too low.

GK

I took it to Precision Motive earlier today. It's a specialty shop that deals in sporty/muscle cars. Specifically, Corvette's.

The owner, Pat, was a very nice guy. He is booked 1-2 weeks out, so I will need to call them Monday to squeeze in and possibly deal with a rental car.

He said it could be many things, but he focused primarily on the valve(s). I believe he said it could be the valve train.

Or, paraphrasing here: a tube that normally sends oil went bad and is possibly could be sending air(?).

I asked him if it was safe to drive and he suggested I do not. He asked to add an extra court of oil. He described the ticking sound as a nail that is being flattened into a mushroom top every time I hear that tick.

He did recommend one other guy that he trusts that works on these vehicles. Left them a message to see how long their back log is.

I just went over the car (yet again) with a fine tooth comb and all cables seem to be perfectly in tact. Checked the connections all the way to the spark plug and everything feels nice and solid. Made sure all visible adaptors that I could disconnect under the vanity covers were disconnected and checked and cleaned for dirt, etc with compressed air.

My mechanical experience ends here, so your thoughts would be appreciated.

EDIT: Forgot to mention I disconnected the negative battery post in hopes of "resetting" something. Didn't work. Ticking persists.s

tcrote5516

Well pulling the battery often resets valves You sir have a screamingly obvious mechanical issue and not one of the million electrical gremlins that reside in these cars. DO NOT DRIVE IT. That's not a happy noise and the oil pressure is validating you have a real problem.

GK

She's parked and waiting to be serviced. I rented a car online that I will pick up tomorrow.

I'll need to drive the Vette it to the shop (again). Luckily, it's only about 6 miles away from home.

ArtGle

A Tow on a flat bed would be cheaper than the possible harm you'd do driving it.
A six mile tow costs a LOT LESS than an engine.
Just my way of doing things in your situation.

andrec10

3boystoys

HUH, what are you smokin, pulling the battery resets the valves

vpshockwave

It does if you do it right after you re-fill your blinker fluid.

GK

An update guys.

Yesterday, I isolated the ticking sound using a stethoscope. It was coming out loudest roughly between the two coil packs closest to the driver when I probed the valve covers.

The girlfriends brother works on cars, so I told him to take a crack at it. I figured it couldn't hurt to look just under the valve covers. If it required more heavy duty work, I was prepared to hand it over.

Well....

One of the roller rockers(sp?) has an incredible amount of play. Every other one on the drivers side had very little play or none. This particular one moved so much that we were able to emulate the ticking sound it made when the engine was running by rocking it.

We went out to a local auto shop in hopes of finding one roller rocker, but they did not carry them. We did however get a new push rod as that stock unit looked like it had been worked over a bit.

We're going to try another place tomorrow in hopes that they sell just one rocker.

GK

Oh, the P0300 code... See attached.

The other cables seem like they were on their way out too. Swapping them for some MSD 8.5 MM cables (scored a custom set for $20).

The OEM plugs from 10/2003 have white oxidation, so good opportunity to give her a tune up. Besides the slight oxidation, the plugs looked perfect!

With the valve cover removed, the car looked gorgeous. No sludge to be found anywhere - just nice clean oil!

tcrote5516

Are you remotely familiar with sarcasm?

BADBIRDCAGE

I am no expert on LS engines in any way, including oil pressure norms, but everyone I know with a stock LS engine with some miles on it runs between 20 and 30 pounds oil pressure at operating temperature idle. Most between 20 and 25. 40 pounds down the road yes but not at warm/hot idle.

My stock LS 1 with 106 thousand miles on it runs right at 20 warm idle and 38 to 43 at speed.

GK

Another update...

I called a local Chevy dealer and they sell single rockers for $15 a pop. Awesome!

Going to try and swing by there to pick one up. I'll grab MSD cables from Vic Hubbard's (actually cheaper than OEM and 1.5 MM thicker).

GK

Unfortunately, a new rocker was not the issue.

The old rocker definitely had a lot more play than the new one, so I was hoping this was it. My buddy was also pretty confident it was the rocker.

After putting everything back together along with a quick tune up, I fired her up.

The ticking was still there.

I let it run until it was at operating temperature (192* for me) to check the oil pressure. Still a lot lower than what I remember; turned it off.

Looks like I'll be taking it into the shop tomorrow morning.

92GA

Sounds like a busted lifter. If it is, the cam is probably toast too.

GK

Funny you mention cam. He reputedly was saying "I hope the cam isn't f'ed."

Looks like I'll find out soon. The fellow I am taking it to said he wants to try to have it ready for me in 1 day, 2 at the latest.

That seems like it's to good to be true, so we'll see how that goes.