EGR Question

JBRAGAS

MEMBER
FORD E-SERIES VAN

I have a 1986 Ford Econoline 350 with a 460 engine. It is a motorhome with approximately 37,000 miles. It starts good, it runs good most of the time but sometimes when I come to a stop the engine is shaking and rocking real bad, it feels like it wants to shut off. I ignore it and drive on and it seems to go away. Sometimes when I'm actually up to crusing speed of 55 mph I feel a slight surge. Lately it will idle ok and accelerate ok but when I'm driving between 10-20 mph I can now feel the surging has intensified. When I took the vacuum line off of the EGR valve and put another vacuum hose onto the actual hose that I took off of the EGR the engine RPM went up and smoothed out. Understand I was only touching the tips of the rubber hoses together when this happened, the EGR valve was not connected at all. I'm confused I'll take anything you got.
Thanks,
John
P.S. When I put the same live vacum hose to the EGR valve, it shut the engine off.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

It shuts the engine bcuz you have a full manifold vacuum -normally the EGR is provided with a ported vacuum. Meaning above the throttle plate and as you increase the throttle opening the vacuum will gradually increase.

To figure the correct vacuum above throttle plate you need a vacuum gauge-disconnect a vacuum hose above the throttle plate connect the gauge or use your finger and feel for vacuum-you shouldn't have a vacuum, if you got this Tee-in the vacuum hose at the EGR with this nipple and the disconnected hose this will solve your problem.

I hope its a Carb system that's what I gave you.

My type of engine 460 in an F250 75 body w/dual tanks.