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Aaaaand we're back to EGR issues

1995 f150 5.8 253k CA emissions

CEL for insufficient flow. The whole EGR system is rather new except for the vacuum lines. I've explored a lot with this system and have ran the troubleshooting steps numerous times. Usually I can just suck the valve open and the engine starts to stall and then the truck is good for a few months. This time the valve is opening and the there is no change to engine idle. I can hear the valve open and close so now I'm thinking I could have a clogged area where the flow goes into intake or an exhaust leak?
 
So I'm thinking to take the valve off the engine but leave it connected to tube, block the intake port and turn truck on and open valve. If good flow is coming out of valve then the issue is it's clogged on the intake side. Does that sound like a reasonable start?
 
So I have narrowed down my issue and have taken everything off down to my exhaust manifold EGR connector. How do you clean/check for exhaust manifold blockage or issue? There's such little space to work in, but I'm trying!
 
It was the damn valve again �� Finally got it to fail shut when I blew enough air through it. I only got 3.5 years out of it!
 

dustybumpers

don't play well w others
Have you ever done a compression check on this truck?
Sounds like a lot of base pressure is causing blow by to end up in the upper plenum

Does it "smoke" when you take the oil fill cap off, out of the valve cover, while it's running ?
 
Cleaning the valve didn't help.

I'll have to do smoke test. I've been thinking I'm low on compression for a while now, but is there any point in knowing? My truck lacks a little power but runs great for its age. I've been replacing and repairing what I can prior to an engine rebuild. Is there anything that can fix compression besides an overhaul that is worth a mediocre mechanic attempting?

Thanks for the help guys!
 

dustybumpers

don't play well w others
Yes, if you can keep the bypass oil from going back into the intake , would be a big help.
do the compression test, find out just how bad it is, maybe it's not that, it's another issue, like fuel
Have you pulled the vacuum line off the fuel pressure regulator to see if fuel pressure changes ( with a gauge on)?
 
I'll run a compression test here soon and post results.

Fuel pressure and regulator are good. I recently replaced a fuel pump so I've already checked all the pressures.
 

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