Car 'choking' and oil in plugs

Yoshi · Postby **Yoshi** » Fri Apr 13, 2007 12:55 pm

Hi all,

I have been having a strange problem with my cars recently, if i give the throttle a sudden tap at low rev's the car feels like it wants to clunk out, it sort of 'chokes', like it cant take it.
I experimented, the harder/faster i hit the throttle at idle the more the car struggles. As soon as it gets past this 'choking', it gets higher up it the rev range, and i can rev it as hard as i want, its fine.
Before i took it to a mechanic, i wanted to poke around a bit. When i pulled out the spark plugs, i noticed they had oil on the top, the oil seemed to be working its way down the thread. :shock:

Cylinder 4 was especially bad. It was covered in oil.
Anyone offer some help to this problem. You think the two are related?

Thanks

SuperMazdaKart · Postby **SuperMazdaKart** » Fri Apr 13, 2007 1:21 pm

when was the last time you replaced the spark plugs or have they ever been replaced since you bought it?

worn piston rings maybe, blowing lots of smoke out the back while driving?

hopefully for your sake it's just a case of worn out sparkplugs not firing anymore, fixed by replacing them with new ones. easy & don't cost much either, might as well replace the ignition leads too while your at it if they're old.

ampz · Postby **ampz** » Fri Apr 13, 2007 1:31 pm

My money would be on a vacuum leak somewhere.
Check all your hoses and also the cam cover valve thingy.

The oil in your spark plug wells would be a leaky cover gasket. Especially if it is working its way fromt he top of the plug down...

Would the mx5s be sensitive enough to hesitate if the cam cover gasket is compromised?
(the lexus is200 will stumble if it is)

Babalouie · Postby **Babalouie** » Fri Apr 13, 2007 2:05 pm

http://www.magnecor.com/magnecor1/techb ... echmaz.htm

It's a common problem on our cars. The valve cover gasket leaks and junk goes down the plug wells and contaminates the plug wires. I think once plug wires are contaminated with oil, they are junk, so you will probably have to get a new set. While you're at the parts counter get a new cam cover gasket too

Yoshi · Postby **Yoshi** » Fri Apr 13, 2007 2:58 pm

Thanks guys

Babalouie wrote:http://www.magnecor.com/magnecor1/techbulletins/techmaz.htm

It's a common problem on our cars. The valve cover gasket leaks and junk goes down the plug wells and contaminates the plug wires. I think once plug wires are contaminated with oil, they are junk, so you will probably have to get a new set. While you're at the parts counter get a new cam cover gasket too

Sounds like a likely scenario, plus from what i have been reading valve cover gasket is the cause for oil at the top of the plugs due to the gasket leaking.

I just changed the plugs to try something quick, and the problem still occurs, guessing the leads are gone due to the oil. I'm going to put back the old plugs for now as i don't want to risk damage to the new ones.

I'm going to try the whole clean out spark plug wells, replace leads, replace plugs and replace cam cover gasket to try and fix the problem.

Replace cam cover gasket, sounds a bit tricky.

Yoshi · Postby **Yoshi** » Fri Apr 13, 2007 3:16 pm

On closer investigation ( not too close, it was poking me right in the eye! ) i can see from the outside of the engine oil leaking out the gasket, worse at cylinder 4, were i had the most oil on the spark plug, surprise, surprise.

The bolts in the top could have used a very slight bit of tightening, nothing too bad they were pretty tight and some didn't even move.

Looks like its new gasket for me, hope once all this is solved, the throttle \"choke\" problem will go too.

Babalouie · Postby **Babalouie** » Fri Apr 13, 2007 3:21 pm

Yoshi wrote:Replace cam cover gasket, sounds a bit tricky.

Nah, not really. Instructions here:
http://www.miata.net/garage/valvecover/index.html

The only thing I would add to those instructions are that the cam cover will be pretty stuck fast, so I tap the breather hose outlet gently upwards with a rubber hammer to dislodge the cover.

Make sure you tighten the cover in that special order though. The bolts don't have to be super-tight, if you don't have a torque wrench, just undo one half a turn and re-tighten it half a turn to gauge how tight it should be by hand.

muzza2 · Postby **muzza2** » Sat Apr 14, 2007 10:03 pm

yeah had the same problem with my engine
my solution was to change the engine :lol:

i'll rebuild mine later...
but i'll confirm what everyone has said, yes it has alot to do with the rocket cover gasket, change that and ur problems will be fine.
also i found with mind when it had oil in the spark plug hole if did the \"choke\" thing aswell.
clean it out with a rag & a screw driver or something like that (dont get the rag in the piston for obvious reasons....)
once its clean it was fine for 2 or so months, then the oil came back...
so its a bandaid solution but it works...