Camshaft wear

When you look at the lobes are the edges rounded or square? Can you take a picture of the lobes in question and upload them? I can tell from that.

Hi and thanks for using 2CarPros.com.

If there is that much wear on the lobe, it sounds bad. The standard manufacturing tolerance is + - .005".

Let me know if this helps.

Take care,
Joe

I was hoping to find out how much wear the intake lobes can take and a re-builder would use it or replace it. I replaced the catalytic converters three years ago and that stopped the random misfire for one year. Recently at freeway speed it started a miss that would go away on restart until you try to drive over 50 MPH. Since the intake valves are not caked with carbon, what might be wrong?

It sounds more like a regular misfire to me. I would do a full tune up including servicing the throttle bore. Here are two guides to help you:

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and

https://www.2carpros.com/articles/throttle-actuator-service

Lets run the codes as well.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down these guides and report back.

Cheers, Ken

Does the lack of supporting codes indicate the last tuneup I did is still good? Only codes are random misfire on all cylinder. When I try and go over 50 MPH the check engine light starts flashing and then the the dead miss starts, until I shut off the engine. When I recrank the dead miss is gone and the check engine light goes back to steady. Is there a limp mode? While it is in miss(still running) codes are random misfire. Will a new air filter fix it? Is my camshaft wore out?

Hi and welcome back.

A dead miss is when one or more of the cylinders begin to misfire all the time and not at random times. Is the only code you get the random misfire (P0300)? As far as the cam, I honestly do not think it would cause a dead miss. Even though it is beyond what is considered tolerance, I feel it would miss all the time if the cam was the issue.

Next, have you confirmed that fuel pressure is within the manufacturer's specs? Weak pressure can cause a random misfire.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

As far as the camshaft, a re-builder would replace it because it exceeds the maximum that is considered acceptable. Also, unless the air filter it plugged, it should not be the cause unless it is really bad.

Focus on the things that both Ken and I suggested. Let us know what you find. One last thought. With 275,000 miles on the vehicle, you have to keep in mind that engine compression it self could be an issue.

Let us know what you find.

Joe