asylvester

Most posts list the problem and potential solutions but rarely do I see the confirmed fix! So, after pulling my hair out trying to figure out the P0505 I wanted to share how I finally fixed it. Symptoms other than the CEL were high/surging idle and bucking when on/off gas. I had sprayed carb spray on cold running motor to check for vacuum leaks-none. I foolishly bought an IAC valve (luckily only paid $50) The culprit was the f&%#,n PCV valve. Only use a Honda one, it made all the difference and the CEL finally went away.

ezone

Oh that's good, thanks

mac25

Rep added for good info =D.

Wankenstein

OP.. How did you isolate the issue to the PCV valve? Testing or random part changing. Was it blocked (ball not rattling) or torn PCV hose or other?

I've used aftermarket PCV's without issue a few times. I'd prefer an OEM but they are more expensive and can be a longer wait if ordering from dealer or online.

ezone

I would think that symptoms would start as soon as the aftermarket part was installed.

A PCV valve not only has a job to do, it is also a calibrated vacuum leak. If the new part does not flow the same amount as the original, it effectively becomes an extra vacuum leak and it can throw off things like idle speed...and/or....fuel trims.

I guarantee you can pull all of your hair out trying to figure it out..you can't hear it....and it's sure not the first thing anyone usually thinks of as a cause.

Back in the days I was at a Mazda dealer, I used to run into issues with carbureted cars having lean idle conditions caused by PCV that flowed too much.
I have seen some Ford products set lean codes that were caused by a faulty PCV valve.

Wankenstein

Thanks Ezone ..good info. I will try an OEM pcv valve next time I do an oil change. My car's engine does have a slightly low idle that's improved when I turn on the headlights or a/c so, might be related to PCV air flow.

What's a carburetor?..lol

ezone

Have you compared to other identical cars? The idle-up due to electrical load sounds sort of expected IMO, but I don't have any cars that old to compare to.


A very primitive air-fuel mixing device mainly found in museums.....

Back when I was in school, fuel injection was for Diesels, racing, and exotic cars.
For regular everyday cars fuel injection was just a passing fad. It would never catch on.

If I see something that old roll into the shop nowadays, I run and hide. I feel sick. I hear my mom calling.

mac25

[QUOTE=What's a carburetor?..lol[/QUOTE]

...not sure if serious, or joking? lol.

Wankenstein

This is my second 6th Gen EX. The first (manual transmission) EX would idle up during electrical load and I do expect that with this one too. However, my current EX (automatic transmission) needs an electrical load to reach a smoother idle around 750 +/-. Without an electrical load it idles around 550 +/- rpm. According to this read: http://my.prostreetonline.com/2015/0...ic-idle-speed/ my car's engine idle is in range but, it feels rougher than how my prior EX (MT) felt.

Wankenstein

Yes..I was joking. Some of the young folks here may not have seen an automotive engine with a carburator before.

Carbuff2

You haven't LIVED until you have attempted to balance six carbs on an exotic car.

PS: A Manometer is NOT how you measure male capability!

ezone

My life was going along just fine until I had to learn how. Now I wear jackets with extra long sleeves that tie in the back.

I can make a water manometer if I have to, and I still have an old Uni-Syn in my toolbox: