Rough idle

[Sadden]

Started it up one day and it was idling poorly.
Sounded and felt like it was mssing a cylinder completely.
Did the plugs and wires.
No dice.
Cleaned the MAF
No dice.
the only other thing i can think of is cleaning the EGR?

Help me please.

[harofreak00]

No SES?

[azu]

Bad coil(s)?

[Sadden]

Not until we unplugged the MAF while it was running..
Still have no clue what to do..
i should service the EGR anyways.
As it probably has not been done in this cars 255K lifetime.

Yeah coils are on the short list.

[Sadden]

Actually i checked the coils.
No dice they are firing fine.
How hard is it to service the EGR?
I mean its right there it looks like it shouldn't be too hard...

[LeSabre in Buffalo]

Could try a Seafoam or water decarbonization. The water isn't too hard. Disconnect a vacuum hose on the throttle body after the throttle plate, and let the engine very slowly suck in half a gallon of water while you rev the engine by pressing on the throttle. Don't suck a lot in at once, it won't burn off. The goal is to make steam to free the carbon in the cylinders, not kill the engine. When I did this to my car, it steamed a little and ran smoother after I changed the oil. Which, I've never seen oil that black before...

Something to think about.

[Sadden]

I just used some combustion chamber cleaner on the motor.
Applied through the brake booster line.

Thank you.

[Sadden]

New suspiscions.
Looked at a diagram with dad.
We think that the Combustion chamber cleaner gummed up the idle air control valve (terminology?)
Its either that or the EGR.

[myfirstbonnie]

The idle air control (IAC) is on the side of the TB and does nothing more than allow air to bypass the throttle plate to keep the car idle. It is a servo motor that is fed a signal from the PCM and runs a plunger in and out to set the idle to the desired RPM's. By adding it through the brake booster line, the cleaner never touched the IAC. What cleaner did you use?

Actually i checked the coils.
No dice they are firing fine.

How did you check the coils? http://www.pontiacbonnevilleclub.com/fo ... =48&t=1683

[Sadden]

Pull wire off coil
Stick screwdriver in wire
Start car
Touch screwdriver to coil
See sparky
Coil good

And i didn't start it through the Brake Booster line.
i pulled the hose off the air box and started it through the MAF screen.

[myfirstbonnie]

I would clean the MAF or get a new / used one. According to your previous post, you did:

I just used some combustion chamber cleaner on the motor.
Applied through the brake booster line.

Thank you.

Test the coils they way described in the link I posted.

[Sadden]

Cleaned the MAF already.
Dont have the electronics to do so as they are locked up in dads stall at work and my parents are 19 days away.


Checking / Cleaning the IAC
Then Cleaning the EGR
And then replacing the MAF

In that order.
Whichever takes care of it first.
Dad thinks its something blocking the IAC

[myfirstbonnie]

If you ran cleaner through the MAF, I am going to put my bet on that. I got a used one from the yard for $50. What does it do if you unplug the MAF while it is running?

Try disconnecting the MAF and battery for several minutes and then only connect the battery and start it with the MAF disconnected and see how it runs after a few minutes of idling. This will set the tables back to default and will not even try to use a MAF input.

Did you check all 3 coils?

[Sadden]

Yeah we checked all three.
and every terminal of the three

That sounds like a good idea.
I will unplug said item and go for a movie and try when i get home.
How long should it take for the idle to smooth out if it is the MAF

[myfirstbonnie]

Shouldn't take long.

Does it start fine and idle ok when cold and get worse after it has warmed up, or the other way around, or all the time?

[Sadden]

Rough all the time.
But only on idle.
Above... 1200 rpm(guesstimation. No tach in the engine bay )
it smooths right out

[Sadden]

I tried testing as suggested.
The MAF does not seem to be affecting it.
It ran just as rough only this time alot richer than it was before (it was already smelling rich)

I'm trying to take the IAC unit off but some moron used screws to hold it in place.
And i could take the TB off but i don't want to because i have a gen2 SC with a gen3 TB and i have no clue how the previous owner managed to seal it and i don't particularly want find out either.. (not until my gen 3 sc is ready to go on along with brand new gaskets LIM TB SC etc..)

[Sadden]

Finnaly got the IAC off today.
Cleaned it and the hole.
No debris.

It did not fix my issue.
No SES
Extremely rough idle.

I am at a loss.

Dad wants me to pull the plugs again so he can take a look at them
Idk why.
He says he wants to try and see whats going on in the chamber.

I am at a complete loss.
My suspiscions are the MAF and/or EGR.

Any input?

[willwren]

i have a gen2 SC with a gen3 TB

This.

They don't mate properly. Airflow disruptions and mismatches are getting you nothing in terms of performance, as even though the TB has a larger bore, the inlet of the supercharger is a restriction. Please swap back to the proper TB and sensors and try again.

[Sadden]

I know they are not a direct bolt on.

But i do NOT want to open that little rats nest until my Gen3 is rebuilt and ready to go which it will not be for at least another month probably.
The car ran fine for 6 months with me driving on that setup.
It didn't get pissy till

After i ran combustion chamber cleaner through it
After i got gas with cornswill (94 octane with "10%" swill)

And for those reasons i do not think that the SC/TB combo is causing my issues.
Could you explain further as to why you think this is the cause?
I know its wrong. But i don't currently have the means to replace the SC.

My suspiscion is that all the carbon loosened by the combustion chamber cleaner got deposited in the EGR.

Anyways im about to go pull the plugs and go do a cranking compression test..
Ill check back in a little bit.