Engine rough idle - eliminating possibilities

[phamnett]

So it started when I had to replace my egr valve. During the replacement the studs on the egr adapter seized and broke off. I tried to replace the egr adapter only to find the one I purchased didn't have the stovepipe attached. So it's the same adapter with a new egr valve duct taped on to it.

That's the end of the first part. No problems for a few kilometers after that, until the engine starts rough idling. I look under the hood and a spark plug wire has burnt off. I replaced all the spark plugs and wire. Then I drive a few more kilometers and steam starts coming out from under the hood - the upper radiator hose is cracker. I replaced it. The engine then continues to rough idle. I flush the coolant, check the other hoses, and clean the reservoir. The rough idle continued. I change the oil and the filter. But it's still rough idling and just added stop leak to the coolant.

I have a 2001 Pontiac Bonneville SSEI with 200,000km. Does it sound like a cylinder problem or lim gasket that would cause the rough idle?

Scanner only reads PO303 cylinder 3 misfire and PO300.

[nos4blood70]

Check plug and coil for cylinder three.

[mrrcom]

i had a rough idle, first i thought it was the crank position sensor but after a new one didnt help i removed the idle air control valve and cleaned it. it helped but i eventually needed to replace it. it didnt throw a code either.

maybe you could try it? cleaning is free and its easy to get at

[phamnett]

I threw in some JBs Stop Leak powder in the coolant system and the rough idling stopped. Does that mean it was the lim gasket?

[phamnett]

Now it seems to only rough idle sometimes when it starts when the engine is hot.

[nos4blood70]

Were you losing coolant beforehand? Have the LIM gaskets ever been done? Have you ever changed the spark plugs, or the coils and the ignition control module?

[phamnett]

I changed the spark plugs, and wire. There was a bit off coolant coming out, so I flushed the system and put in JBs stop leak powder. The system never overheated. The LIM gasket hasn't ever been done. I switched from orange dex-cool to green stuff. Where are instructions for replacing LIM gasket with supercharger?

[1oldman]

I changed the spark plugs, and wire. There was a bit off coolant coming out, so I flushed the system and put in JBs stop leak powder. The system never overheated. The LIM gasket hasn't ever been done. I switched from orange dex-cool to green stuff. Where are instructions for replacing LIM gasket with supercharger?

Try These:

Valve Cover Gaskets: http://www.pontiacbonnevilleclub.com/fo ... c6879.html
LIM & Plenium & Supercharger: http://www.pontiacbonnevilleclub.com/fo ... er#p420595

- BC