Diagnosing Slight Engine Miss

[1turbo6]

not noticeable while driving, it idles like it's on 5 cylinders ( motor shakes alot)and minor popping out the exhaust if I hold rpm up at 1800 or so. the Car went to a buick guy a few years ago for tuning due to low boost knock and I was told the car was lean (duh!) and he put alcohol kit in it. but the issue was never resolved. I have swapped ecm's, tried unplugging injectors all kinds of things almost seems like this type of thing...

http://www.turbobuick.com/forums/threads/very-odd-ignition-problem.334036/#post-2641561

 

[1turbo6]

Minor pop out the exhaust but engine shakes at idle like it's on 5 cylinders. Any ideas?

 

[GNONYX]

Have you try what I sent to you on thread #17?
If not try it and let us know the outcome

 

[TurboBuRick]

Can you pull the plugs and snap some pics? Number them as well. Maybe they can tell us something.

RL

 

[wahoo50]

Have had this same problem with my GN for the past two years, never drive it now. Have replaced everything on the engine except injectors, so I replaced them this past week, no help. Missing while idling, miss goes away when accelerating, once you start to build boost it will backfire through the exhaust. Will be watching for the solution to your problem.

 

[buickruss]

vacuum gauge on the car?

is it steady at idle and whats the #?

 

[1turbo6]

I just tried the test mentioned in thread 17 and did notice a slight difference in the idle.

 

[Pronto]

Check page 98 of the Buick manual I sent you.

 

[1turbo6]

hooked up boost to powerlogger and it shows 17-18 " vacuum. also took car for a ride and recorded a log. not sure what to look for everything seems ok to me.

 

[Nick Micale]

I could be wrong, but i disagree. Why would pulling one wire kill the other plug on the same coil? I agree that if one of the coils was bad, it would kill two plugs. However if you pull a wire off of one coil tower, it should not kill the other.

You are correct Dan!

I have done this a few hundred times to find a dead hole.