name this egr related part, what does it do???

[GMCLegacy]

i'm attempting to get a 92 tbi 350 to run without hesitation. after searching around here i decided to throw a new egr in. this didnt solve a thing. long story short, the truck runs good if i bypass "unknown part".

it is inline with the vacuum line that feeds the egr valve. it has a 2 prong connector on it. is it needed, if so, what does it do? the truck seems to run good with straight vacuum on the egr.

 

[dyeager535]

It's the EGR solenoid. It opens to allow engine vacuum to pull the EGR valve open.

It wouldn't be there if it wasn't needed.

 

[GMCLegacy]

thanks for the help,

does it limit the amount of vacuum the egr receives? does the solenoid recieve a 12 volt signal?

i found it on advances site, at least they are cheaper than the egr valve...16 bucks
http://www.partsamerica.com/Product...S&mfrpartnumber=7799622&parttype=1420&ptset=A

 

[dyeager535]

It's open or closed. Receives a signal from the ECM and it opens.

There are typically three "connections" on the solenoid, one barbed that is a VENT line. The other two from my experience use a formed rubber plug so you can't hook them up wrong, but not sure what the '92 truck piece looks like.

With it disconnected you are "bypassing" EGR as a whole, so that doesn't mean the solenoid is the cause. Did you clean out the EGR passages when you replaced the valve?

 

[GMCLegacy]

i did not clean the egr passage, mainly because i could not see any build up. i think i replaced a working egr valve. i am thinking it is a solenoid problem because if i run a vacuum line from the tbi to the egr it runs good.

i put the solenoid back inline and could not get vacuum at the egr. at what point(s) does the ecm tell the solenoid to give the egr vacuum?

 

[dyeager535]

ECM is programmed for what conditions to operate in, generally it will be with steady cruise. (time at speed threshold probably, with high engine vacuum)

There are two general types of EGR valves, I'm not quite sure how they work if vacuum isn't used to pull the valve open, or if it's just another way of doing the same thing.

If you can put vacuum to the EGR at idle and it runs ok, something is either wrong, or the valve operates differently than the ones we commonly deal with on the trucks. You've made sure that whatever line you are hooking up to the EGR is also clear of blockages and doesn't leak?