Rough idle? Best place to start!

[Anonymous]

For some, and myself, a rough idle can be a pain in the butt to fix. Most of the time the individual ends up spending money on everything from carburetors to rebuild transmissions and still can't figure it out.

Speaking from experience I have done just about everything to my engine and transmission. Up until yesterday I was just about to junk the motor and start over (thinking V8 again ).

So to make a long story short, and not so boring, the FIRST thing someone should do when tackling an idle problem is to preform a cylinder compression test on ALL 6 cylinders. It's an easy, quick, and simple job. A 15.00 guage is all you need and possibly someone else to help you crank the car while you take the readings.

The guage I have will hold the compressed air in the unit until I push a release button to exhuast the air out of the guage. This way all I had to do was to hook up the guage to the spark plug hole (make sure ALL are out) and crank the car a few seconds.

When you perform this test on ALL the cylinders ALOT can be determined by the results! Example. For the past six months my car has been smoking out of the breather cap and none from the tailpipe. It would not idle correctly no matter what I did in regards to engine tuning. Finally a friend asked if I had preformed a compression test on all the cylinders. I said no and thought - well it couldn't hurt, I've done everything else. So, a quick trip to Autozone and 30 minutes later I knew what my problem was! BAD oil and compression rings on number 2 cylinder.

All cylinders where reading between 140 and 150 PSI EXCEPT number 2 - 30 PSI! Talk about a big difference! So this week I'll be rebuilding the engine. :x

It's amazing how much money I could have saved AND time if I had know this from the beginning. SOOOOO....

If anyone else just can't get their car to idle smoothly. It wouldn't hurt to perform a compression test on your car before you start tearing it apart and spending alot of money on things that are probably working fine.

I can't stress enough how easy and important it is to do this simple task.

Hope this message helps someone


-Chris

 

[CobraSix]

You should probably do it even if you think your engine is running fine. It lets you know how good of condition your engine is in.

Speaking of which, I need to get off of my lazy butt and do a test on my new engine.

Slade

 

[Anonymous]

notice to do a dry and wet test . i did a dry test , al cyl where good almost even , but noticed that cyl 3 was wet and the spark also got oil on it ! , after a wet test al the cyl compressie was higher then cyl 3 !!!!

they told me when a cyl is leaking oil , the compressie after testing is higher , example dry testing i got about 7 bar ! al cyl

wet tesing , stil the nr 3 cyl 7 bar and al the others almost 9,5 bar !!

after problems with the engine that was sounding al the time it was misfiring i checkt the sparks , and cyl 3 was verry wet and the spark also !
timing new setting didnt help , could turn the timing 1 cm up ore down , but stil misfiring ! i got a dura ll with msd6a and a mallory promaster coil .
with new spark wiring 8 m/m new rotor cap new sparks ....... didnt help stil misfirng, tested the spark cable,s and there sparking good , the sparks themself too !! no misfiring in the spark wiring !!

the car is runnig great ,drive it stil every day , little misfiring , but got in a couple weeks al my parts for a 5 lug swap and T5 , so then i wil take the engine out and see what is the real problem !!

btw i markt the spark [ cyl 3 ] before i got it out ! the markt site [ towards the valve cover ] was verry wet.. realy oily , and the other site [ towards the oilpan ] was nice yellow, good burning spark ? ever did seen a spark 1 site oily and 1 site nice yellow !!
is it possible i got a leaking head gasket only ? valve stem leaking ?

 

[addo]

Thanks for posting this, Chris. It's impossible to have too much information about your engine. I hope the problem can be fixed by a hone and new rings on #3.

Adam.