Chevy & GMC Vans

i did a full tune-up and checked for misfire and there is none all plugs firing here is the problem when the engine is idleing in park i can feel the engine viberting more then it should when cold it is not as pronouced but when warm it is it feels like a misfire at idle when i put the van into gear i really feel it doing it feels like a rough and misfire idle only no other problems it is pretty strong engine just weird and annoying vibes at idle. this a 1992 TBI astro 2 wd.

Start with the EGR, pull it and check for carbon causing the pintle to stick
You also might double check your distributor cap and make sure it is screwed down tight.

I would pull each plug wire off and make sure they all are firing...then spray some soapy water around and check for a vacum leak,or carb cleaner, but make sure the engine is not hot, might get your self in a situation know as a "fire"

i did the plug trick and came up empty here is something weird when i come to a stop or anytime i am stopped it seems and feels like my idle is too low. but i have not ruled out a vac leak but the idle would be higher.

could a EGR valve acting up cause a low idle and make it rough? cause that is what i am leaning towards also the exhaust does smell a little rich could EGR valve cause that?

92astro wrote:could a EGR valve acting up cause a low idle and make it rough? cause that is what i am leaning towards also the exhaust does smell a little rich could EGR valve cause that?

Yep stuck open EGR can cause all those symptoms. If its wide open it will sound like you have a crazy cam... lopey low idle and run VERY rich. Might even want to stall when you come to a stop or try to get going again.

Check the MAP too...

if the egr is sticking open at idle is it cause of carbon or low vac?

also how should i test the egr valve?

Just take the vacume from it and see if it runs better or put a finger underneath it and push up, the engine will stall or die.

s10-den wrote:Just take the vacume from it and see if it runs better or put a finger underneath it and push up, the engine will stall or die.

Bryon,
Look,just take off the ERG and clean out the carbon.Then install a screen gasket.This is a common problem with these vans.

Or do like GEJ says...

s10-den wrote:I would pull each plug wire off and make sure they all are firing...then spray some soapy water around and check for a vacum leak,or carb cleaner, but make sure the engine is not hot, might get your self in a situation know as a "fire"

a vacuum leak sucks, both figuratively and literally, use carb cleaner, you don't want soapy water sucked into your engine.
soapy water works great on natural gas line leaks though...

also, the screened egr gasket is definitely the way to go as Gary suggested. Tomco has them online, but make sure the gasket pattern matches your egr. They sold me a wrong gasket. They don't have the gasket pattern for my '89.

The only way to push the egr in with your finger is if you've removed it, at which point you have a massive vacuum leak

If your egr was stuck closed, you'd experience engine knock when accelerating, which if you knew what you were listening for you'd hear, if not you'd notice the lack of power on acceleration. If it was stuck open, it'd idle like crud. If you haven't already, pull it and clean it anyway. Also clean the holes, ports, in the engine block as best you can.
If you are smelling gas, it's running rich or misfiring. If you don't have a service engine light on, it's probably not the map sensor. you may have a fuel injector that is sticking open and peeing gas into the throttle body rather than spraying it.
sticking injectors on the model 220 throttle body injection do not throw codes. this I know from personal experience. My engine almost hydro-locked due to both injectors stuck wide open. remove the air cleaner housing, remove the vacuum hose from the backside of the throttle body intake, the hose that routes from the top middle down to the driver's side rocker cover. the TBI intake shroud can then be removed by hand so you can see the injectors. get a flashlight and just turn the key to the on position, the fuel pump will cycle for about 2 seconds, you should see a fine cone shaped mist from the injectors, if you see liquid dripping gas from either of the injectors, it's toast. If so, by oem injectors to replace, do not buy rebuilt injectors. The oem injectors are expensive as hell, but they will work the first time and last a long long time.

One last thought, these vans are really picky about distributor caps and the terminals in the caps, some model years run great with caps with aluminum terminals and some run great with brass terminals, my '89 is the latter. It did just fine with aluminum terminals for a short while, then almost left me stranded. I replaced the cap I had recently bought with a bosch brass terminal cap and have had no problems since.

Soapy water will be fine.Been there done that thousands of times wont hurt a thing.If you have that bad of a leak, your in big trouble anyways.I have seen a egr and a map go out and not trigger a checkengine light.Prolly as this guys problem.If the check engine light is on,just see what the codes are.
On the EGR,I havent looked at an astro unit, but ons10's all you have to do is push it up by your finger......I'll have to look at mine and see what it looks like now....

s10-den wrote:Soapy water will be fine.Been there done that thousands of times wont hurt a thing.If you have that bad of a leak, your in big trouble anyways.I have seen a egr and a map go out and not trigger a checkengine light.Prolly as this guys problem.If the check engine light is on,just see what the codes are.
On the EGR,I havent looked at an astro unit, but ons10's all you have to do is push it up by your finger......I'll have to look at mine and see what it looks like now....

Den-just a thought.Wouldn't soapy water bubble on a hot manifold either way??.