ERG Valve

[Hillbillybuddha]

Is there vacuum pressure where the ERG valve mates the the intake manifold?

[ggzilla]

Is it a valve that lets the sand out of the erg?

 

EGR valve connects directly to the intake manifold. There is no vacuum there at heavy throttle, and full vacuum at idle. So if you remove the EGR valve, the holes must be plugged somehow.

 

The hose that connects to the EGR valve has no vacuum at idle, and strong vacuum when engine is making heavy power.

[illestmatic]

In short. Yeah theres same kind of pressure going threw the erg valve or known as the PVC valve.

You need it for idle stability valve basically regulated air into the manifold from the block.

[Hillbillybuddha]

Cool. Thanks. The studs that were originally in the manifold and ran through the EGR were taken out at some point. I tried running bolts through but I think they were to short and/or the wrong thread. I can't get the idle to run steady or below 1200 RMP. It's been driving me mad. I've run smoke through the vacuum system looking for leaks and have found none. I replaced all the vacuum lines just in case. I saw a little exhaust smoke come from the rear of the engine and noticed that I could move the EGR valve with my hand. So I went to pick and pull and grabbed a couple studs.

 

Couple questions. Is there an easy way to remove the EGR? What size is the compression nut on the pipe that runs from the exhaust to the EGR? It seems that 23mm is to small and 24mm is to big, is it a SAE size?

 

Thanks,

Hillbillybuddha

[ggzilla]

No need to remove that tube, you would need the plug the holes if you remove it.

 

And leave the EGR valve bolted on to plug the manifold.

[Hillbillybuddha]

I want to leave it all together, believe me. But I have to get it off to replace the EGR gasket and to install the new studs. I got it on there a few months back because it came from Oregon with all the smog stuff removed. I'm in the process of making it smog legal in cali. My buddy put it on a smog machine a few weeks back and said it was idling high (which I know cause I can't get it below 1200 RMP) and that it was running rich. I'm hunting down those problems.

[ggzilla]

Its a metric fitting. I use a pipe wrench.

 

If it won't idle, check to make sure the idle-cut solenoid has 12V when key is ON.

[Hillbillybuddha]

The truck is an "out of state" truck that came with a weber carb. I pulled a cab from the yard. It's a California carb with the wires coming off. BUT the truck doesn't have the correct harness to plug into the carb. There are no loose wires at all near the carb, coming from the truck.

 

I was reading through some of your older posts about the idle cut solenoid and you wrote, "When your engine won't idle, always check the idle-cut solenoid first. You don't have to replace it, your engine don't need one to run well. Removing the pintle will fix it." Can you please explain what a "pintle" is and how to remove it.

[ggzilla]

It may be a 720 feedback carb, which needs an ECU to work correctly. I think those have six wires.

 

 

Regarding the anti-cut solenoid, unscrew it from the carb, pull the pintle (needle) out, then screw it back in. It will no longer cut the idle, allowing the engine to idle.

[Hillbillybuddha]

I'll count the wires in the morning and get back to you. Thanks for helping me with this. I've been working on this truck for 6-8 hours a day for weeks Now. I rebuilt my Ford FE390 engine in half the time I've been messing with this carb. I converted the drum brakes to disc brake on my old Ford in less time than I've been working on this idle. I've rebuilt more old makuni and keihin carbs then I care to Remember but this stupid carb has me at my wit's end.

 

So like I said above. Thanks for helping me here.

[datzenmike]

In short. Yeah theres same kind of pressure going threw the erg valve or known as the PVC valve.

You need it for idle stability valve basically regulated air into the manifold from the block.

 

The PCV is something entirely different and NOT in any way connected to the EGR.

 

The EGR allows inert exhaust gasses into the intake manifold to dilute the charge and lower combustion temperatures and only operates under these conditions.... Above idle and below full throttle, only when the motor is up to full operating temperature. The amount of EGR is varied by the exhaust back pressure which is a good indication of load. No intake vacuum at idle and very low intake vacuum at full throttle means the EGR is off at these times. This will allow it to idle and give full power at full throttle.  

[Hillbillybuddha]

The PCV is something entirely different and NOT in any way connected to the EGR.

  

 

I assumed that GGzilla was having a bit of fun with me when he wrote this. I had miss written EGR as ERG so he used another common example of this mix up and called the PCV a PVC. I'm pretty sure he meant it in jest, but thanks for clearing it up, just in case someone else does get confused about the differences. Also that added info on the EGR, on how and when it works helps me better understand the engine so it's not just an internal combustion engine with all these extra mystery parts.

 

Thanks,

Hillbillybuddha

[datzenmike]

It doesn't really affect performance because it shouldn'e be working at WOT wide open throttle. It tempers all part throttle performance but you won't notice because all you would automatically do is add some more to make up for it. The engine is actually running cooler and less apt to ping.

 

The biggest drawback to having EGR is not maintaining it. The valve can become crusted with deposits and leak exhaust into the intake at idle when it shouldn't and it will run poorly. The exhaust pipe to the EGR can rot away and leak allowing oxygen rich air in that will lean out the mixture. Rubber hoses can leak. If it operating correctly you'll never now it's there. 

[xsdg]

Just to toss this in there, yes, the EGR fitting is a 23mm.  Spray that sucker down with lots of penetrating lubricant so you can get it to rotate.

 

I used a 23mm service wrench with a jack handle to break it loose, and then it turned fine as long as I added more PB Blaster when it got stuck.

[Robert]

 

I want to leave it all together, believe me. But I have to get it off to replace the EGR gasket and to install the new studs. I got it on there a few months back because it came from Oregon with all the smog stuff removed. I'm in the process of making it smog legal in cali. My buddy put it on a smog machine a few weeks back and said it was idling high (which I know cause I can't get it below 1200 RMP) and that it was running rich. I'm hunting down those problems.

 

Your going to run into a problem converting it over to the carb you got from the junkyard. The vehicle is a NON cali and the carb is Cali. BUT i am sure with a good understanding of both systems you could get it working.

 

Get the EGR re-connected and get it idleing where it is suppose to. For the EGR, you need several vacuum actuated selenoids for it to work properly. I am assuming you dont have those anymore. Dont quote me but there should be two...one turns on when the engine is warm, one turns on when the throttle is closed. Both need to be active for the EGR to be active. One more valve closes when there is no engine vacuum prevent flow of gases into the manifold even though the other two are active. It sounds complicated but actually very simple.

 

IF you do not have all the valves, the best way to have it simulate true function is to locate a vacuum port on the carburetor that has no vacuum when the throttle is closed and gets vacuum when the throttle is depressed....connect this directly to the EGR valve thats connected to the manifold. At full throttle there will be no vaccum and it will close and not let gas into the manifold...at part throttle it will have vacuum and reciculate the exhaust, at idle it will have no vacuum and close again....Catch is it will operate when the engines is cold....but thats no biggy...they only smog it when its warm.

 

:)

 

 

Good place for vacuum line routing.

 

http://www.nicoclub.com/archives/nissan-720-pickup-truck-vacuum-hose-diagram-repair-guide.html

 

Ahhhh....the good-ole days of the hose monsters.