Hi,

I've noticed that after shutting off the engine on my truck, there is a buzzing/sucking sound coming from the EGR valve that lasts for about 5-10 seconds as the manifold vacuum drains down. I popped the vacuum off to test and it is the EGR valve. Is this normal? Could this be responsible for just off idle engine roughness?

I have a perfectly smooth idle, but just at about 1000RPM -1500RPM the engine misses and shakes violently, especially under part throttle. Is this a known issue? It is not a real bother because you basically never spend any time at this RPM, but I know something is not right and want to fix it before it gets worse.

Thanks,
Rob

97F150 Flareside 4x4 5.4

 

If your eng surges while holding the accelerator steady, you may have an intake manifold vacuum leak or a clogged air filter. The fuel pump or pressure regulator may be defective.

Your EGR valve may be carboned up. If you remove it to clean it(HOT), clean the inlet and outlet ports with a wire brush or scraper. Do not sand blast the valve or clean it with gasoline or solvents as that will destroy the the EGR valve diaphragm.

Dan

 

If your eng surges while holding the accelerator steady, you may have an intake manifold vacuum leak. a leaky vacuum hose, or a clogged air filter. The fuel pump or pressure regulator may be defective.

Your EGR valve may be carboned up. If you remove it to clean it(HOT), clean the inlet and outlet ports with a wire brush or scraper. Do not sand blast the valve or clean it with gasoline or solvents as that will destroy the the EGR valve diaphragm.

Dan

 

I had the same problem. Roughness at ~1250 rpm. Smooth above and below this range. I replaced the EGR vacuum solenoid, a $25 part. Two mounting bolts, an electrical plug-in connection, and a vacuum plug in connection. Took all of 15 minutes start to finish. Problem solved.