First of all I'm not a mechanic just an avid DIYer. Just had the head off my car for a burnt exhaust valve. Would have done it myself (as I've done it before on another Honda I owned) but did not have the time. Left the car parked in my shop and a local guy I know who is a mechanic pulled the head for me. When the mechanic put it back together it was still missing on #1 and #2 cylinders. When he looked under the car the catalytic converter was glowing red so he tells me the cat is bad and that is probably what caused the burnt valve. I am not one to throw parts at anything so I wanted to do some diagnosing before buying a new cat.

The next off day from work I had I done some troubleshooting. I just so happed to remember that when he pulled the head that he had left the #1 and #2 spark plugs in the head. So I pulled them out and sure enough the gaps was completely closed up on the plugs. He had left them in and when he set the head down it smooshed them. After replacing the plugs the car started right up and runs and idles fine. This also explains the glowing red cat as there was to ignition in #1 and 2 cylinders and the fuel was being burned in the cat.

But he still got me wondering about the cat so I bought and exhaust back pressure gauge and hooked it up today. Only thing is it is not reading anything. You can see the needle just barley jumping even when revved. I'm pretty sure the gauge is working as I can put a small amount of air from my air compressor in it and it will read.

So I said all of that to ask this question: should my car be reading some amount of backpressure when testing??

 

I don't know the answer to your question, but nice find!

 

Don't know much about back pressure valves. I wouldn't trust that mechanic near my car again LOL. He left the plugs in??? I couldn't believe it when I read it.