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rough idle and misfiring

Posted: Sat Feb 04, 2012 9:37 am
by DSkidds
1999 Chevy Astro 156k
Accel Cap/rotor
Ac Delco Irridim plugs
Omni-spark wires
Cherry Bomb Glasspack
Spectre Air Filter


ive replaced the cap/rotor, plugs and wires, catalytic converter, fuel filter, PCV valve and vacuum lines and its still misfiring and rough idle.
i think its the timing but how the hell do you check the timing on these vans? its not throwing any codes.

i think it could be a bad Crankshaft Position sensor and the Ignition Control Module.

Re: rough idle and misfiring

Posted: Sat Feb 04, 2012 11:30 am
by astroturf
Have a lookey at yer EGR Valve.

Re: rough idle and misfiring

Posted: Sat Feb 04, 2012 4:18 pm
by DSkidds
im gonna clean the EGR when i get some money. im also gonna replace the ICM

Re: rough idle and misfiring

Posted: Sat Feb 04, 2012 6:12 pm
by astroturf
Inspection and cleaning of the EGR Valve costs nothing...

Replacing components that haven't failed costs more than even I have to spend.

Good Luck, Jim

Re: rough idle and misfiring

Posted: Sat Feb 04, 2012 6:41 pm
by oldsmoker
wow...i sure hope all of those part replacements were justified.

I had issues with the idle air control valve on mine, does your have one?

Re: rough idle and misfiring

Posted: Mon Feb 06, 2012 3:09 pm
by DSkidds
i don't really know if my 99 astro has an idle control valve. but where is the EGR valve on my van?
the one thing that im gonna replace no matter what is the ignition control valve and once i find the EGR valve its gonna be cleaned.

its started to miss and idle rough once i had my Cherry Bomb glasspack installed.

Re: rough idle and misfiring

Posted: Tue Feb 07, 2012 8:33 am
by LiftedAWDAstro
Chances it is the cap/rotor and wires. These engines are very picky on ignition parts. OEM is what makes them run best. We've seen it here a hundred times where new aftermarket parts fail after a very short time.

Re: rough idle and misfiring

Posted: Wed Feb 08, 2012 3:11 pm
by DSkidds
i have not changed my cap/rotor since August 12k miles ago. it still has the Accel cap/rotor.
i replaced the wires with Omni-Spark from O'reileys for $33, they were replaced last week 100 miles ago.
when i get my taxes im gonna clean the EGR and put a new cap/rotor.



where and what kind of cap/rotor should i install? Duralast Gold?

Re: rough idle and misfiring

Posted: Wed Feb 08, 2012 3:15 pm
by astroturf
Because of the heat found in the engine bay area. It has been said that AC Delco Cap and Rotor are the best.

It is what I use, and what others recommend.

Good Luck and Keep us posted.

Jim

Re: rough idle and misfiring

Posted: Wed Feb 08, 2012 3:15 pm
by MountainManJoe
OEM = GM Brand = AC/Delco

Re: rough idle and misfiring

Posted: Wed Feb 08, 2012 3:20 pm
by DSkidds
Ac Delco it is for me. THANKs

what should i use to clean the EGR valve?

Re: rough idle and misfiring

Posted: Thu Feb 09, 2012 5:04 am
by LiftedAWDAstro
Carb cleaner will work on the EGR.

Re: rough idle and misfiring

Posted: Thu Feb 09, 2012 7:58 am
by astroturf
DSkidds wrote:but where is the EGR valve on my van?
Go here: http://www.gmpartsgiant.com/Page_Produc ... =TM0330401

Click the BLUE Get Info button, Then click GO...

There is your EGR Valve. It will prolly be dirty, like this:
egr valve with carbon trash found inside.jpg
Clean it up real good to look like this:
egr valve nice and clean.jpg
Make sure you go to your local auto parts store and buy an EGR Valve Clean Screen, Like this:
egr clean screen gasket and old gasket.jpg
I would recommend that you do these things before you spend another penny.

Good Luck, Jim

Re: rough idle and misfiring

Posted: Thu Feb 09, 2012 8:55 am
by 1Gary
Just a thought.Take the O2 sensor and temporary remove it.Run the engine with it off to see if it improves the idle.If it does,then the O2 sensor is bad.

Also take the van to a local parts store.Many of them will scan the van for codes for free.

Re: rough idle and misfiring

Posted: Thu Feb 09, 2012 1:32 pm
by DSkidds
as of now i don't have any money so next paycheck im gonna buy stuff for the EGR valve.
when i was driving home the check engine came on. (it was on before) its saying P0300 (random/multiple misfire)

so next week im cleaning the EGR valve. when my taxes come im replacing the cap/rotor with the AC Delco brand. if those don't fix it then im replacing the Ignition Control Module

cap/rotor $55
ICM $85