Hey guys, I'm getting a rough idle when I start my truck up in the morning. Check engine light came on the other day indicating a rough idle(obviously) and suggested checking vaccum lines for leaks and cleaning the TB.

I just replaced the plugs about two weeks ago, and did not notice this idle issue before. I have the plugs gapped at .040 Should it be tighter?

I pulled the air intake off last night and checked down in the TB with a flash light and do not see any oil in the bottom from a plenum gasket. How noticeable is the plenum gasket failure? Could I see any oil on my plugs? I plan on pulling them off today to see what they look like.

Also, I get a very light valve tap from the motor. Not really loud at all. Is this something I should worry about?

Thanks in advance for any replies.

 

Was it ideling rough before you changed the plugs? I think .040 should be good. Did you check the sticker in the engine compartment for the gap?? What about the cap & rotor button?

 

Factory spec is 0.035 for gap. The most common cause of this is bad plug wires. I'd change the wires, cap, and rotor if you haven't already. Do a compression test. That valve tick would make me wonder if maybe you've got a valve burning or cracked head, but that's very unlikely. If that doesn't clear it up, start checking for vacuum leaks.

 

Man you guys are fast. lol

I did not change the wires, cap, and button. Its only got 58k on it. I can do so though if you guys think thats the culprit.

Isn't that kind of an extreme case for the valves too?

Just strikes me odd that I didn't notice either of these issues till after I replaced the plugs and all.

Not questioning ya'lls knowledge. You know a heck of alot more than me. Just curious.

 

Any other possibilities on the valve tap? Is this something serious I should be worrying about?

 

Change the wires cap and rotor. They should be changed every 50,000 or sooner. The new plugs might not have a really good connection with the old wires. It's best just to do them all at once. And don't get the cheapest wires either. The store's premium brand usually isn't that much more, and will last a lot longer.

The valves are an extreme case. But I'd do a compression test on it just to make sure. Since you're planning on pulling the plugs again anyway, you might as well.

 

Well if you did not have the problem until you changed the plugs...... Maybe you have a wire switched, gap incorrect or more likely the plug wire boot not pushed down onto the plug all the way. Could the 'valve tap' be the wire arcing to the plug from the boot?? DBL check your work.

Cap and rotor only cost like $15. My motor needed cap, rotor and plugs @ 60K so you may as well do it soon.

 

10-4. Thanks guys. I'll give it a try.

 

on your valve tap... you might have a sticky lifter or some gunk in there preventing the lifters from pumping up all the way. I havent had the need to do this but others have recommended it... get a can of seafoam and put about 1/3 in with your oil. this is supposed to clean the inside of the motor and may clear some of the oil passages if they are getting gunked up at all. I'd put it in, drive about 500 miles then do an oil change.

if your not already on synthetic, consider the change. using it I think prevents any kind of sludge buildup. I've use synthetic (Mobile 1) on all my cars for the last 15 years and have never had any sludge buildup or ugly gunk in any of the motors that I've torn down. they all look really clean for a motor.

 

Thanks for the replys guys. Just wanted to say that I changed the cap, rotor, and wires last night and it seems to have solved the rough idle. I didn't have the time to regap the plugs, but plan on doing it this evening.

Thanks for your help.