Rep Power: 313

What can you guys tell me about them?

Other then it generally happens when you go lean in the combustion chamber.

I think I have burnt all my exhaust valves by running 91 octane gas my car its entire life.

Any thoughts on after market valves?

Any thoughts on replacing the stock ones?

How can I tell if I have a burnt valve without removing the head?

Will a compression test prove anything?

So many questions...

 
Rep Power: 388

How can I tell if I have a burnt valve without removing the head?
^ Hmm, I'd be interested to know if there is a way to do this w/o pulling the head. I've been looking for a head, and some of them looks really dark and burnt up, hmm. BUMP!

 
Rep Power: 313

my mechanic said that a "dry" and "wet" compression test should show a loss in compression because of a burnt valve.

Soooooo you technically should be able to "know" you have a burnt valve without removing the head

Doesn’t make me feel any better though…

any input from "civicforums?"

 
Rep Power: 313

To the top during the busiest time for this site!

 
Rep Power: 313

im starting a new thread with a new set of questions...

 
Rep Power: 257

I'd just go buy or rent a compression tester, then compare it with factory specs for the psi in each cylinder.

 
Rep Power: 423

You need to find whats making it run lean, after you figure out if you do actually have a problem.
No sense trying to replace things just to make it happen again. And stop running 91, use 87 like the car is built and tuned to run on.
Aftermarket valves wont solve anything, they'll just allow you to rev the car higher, they arent any more durable against poor combustion than any other valve.

 
Rep Power: 313

What the best way to clean valves without removing the head then?

I’m not running lean. I have a random cylinder misfire on all cylinders and I think it’s because the gas I use.

I’m just worried the damage or carbon buildup is too far to fix my misfire…

So I was considering running new valves and different gas...

Should I buy new valves because I have run 91 since day one?

Or run a ton of fuel cleaner through the car...

Boiler?

 
Rep Power: 310

Switching gas wouldnt hurt. A compression test is probably the best way to tell. I've seen ppl recommend using this stuff:

http://www.seafoamsales.com/motorTuneUpTechGas.htm

BTW, I'm getting random misfire codes also.. po300, 301, 302 and 303. My car runs fine though. Seems harder to start and a lil rougher idle until its warmed up some.

This week I'm gonna check out my fuel pressure and see if its within spec.

 
Rep Power: 313

Same exact thing.^^^ When is the last time you changed your plugs?

Well if changing the gas won’t solve my misfire...

I may consider other things.

Thanks for the link! And post back on your fuel pressure.

One of my friends suggested that too.

 
Rep Power: 313

"...slowly pour 1/3 to 1/2 pint through carburetor or throttle body throat. (If vehicle is port injected slowly pour SEA FOAM through direct manifold vacuum line that will feed all cylinders, possible sources are P.C.V. valve or brake booster line.) This will pull SEA FOAM down on top of the pistons and to the back of the intake valves to dissolve carbon. Turn ignition off. Restart engine after 5 minutes. If severe carbon build up is apparent, use more Sea Foam as previously directed. Make sure exhaust is well ventilated when using Sea Foam in these various ways as fumes will be extreme for a short time."


Ummm is this stuff ok???

 
Rep Power: 310

I changed them when the problem started about 6 months ago now. Put in new NGK plugs(same ones that came stock in my engine).

I'll post back once I check it out.

 
Rep Power: 310

Okay, just checked my fuel pressure and its 42 PSI which is within the 40-47 PSI specification range. So I'm fairly certain its not fuel related, unless its my injectors. I tried to ohm them out but I think my ohmmeter is bad. They do sound like they click fine. Not sure what I'm going to try next. I find it odd that only cylinders 1,2 and 3 get the DTC and not cylinder 4. I had already swapped coil packs around and installed new plugs. Still no luck..

Someone mentioned that his dealer thinks it might be EGR related, but I'm not sure. Anyway... if I find out any more info I'll post back here.

 
Rep Power: 423

Run good gas like Shell, etc... with detergents in it through the motor. Buy 87. Pull the spark plugs and change em. You can run fuel cleaner through it I guess it couldnt hurt but there's some merits to just flooring it and "flushing carbon". 91 doesnt burn as well as 87 there could be a chance that there's just a lot of **** built up, if thats the case you'll probably want the whole head cleaned out.
When I took apart my spare motor, which had 70K on it, it was pretty spotless in there, I was impressed with how clean it was, so I'd think any grimy stuff in there is an issue, but the first thing is to run the compression, and see whats going on. If its missing, it might be flooding or just not igniting because of the 91 octane gas.... and crud not letting air through. You gotta remember that unless VTEC is engaged, these things only run on 1 intake valve... so its important that air moves through there.

 
Rep Power: 313

Dont know if you have "quick trips" were your at but thats where I buy my gas.


It could be a wile before I get another compression test...