Hello all, I hope someone can help me with this.. I recently purchased a 97 F-150 with the 5.4L and its been a great truck up untill about a month ago when I noticed it was stalling and sputtering in the low end of the rpms. If you try to accelerate as slow as possible is stumbles really bad untill a point then seems to run fine in the rest of the rpm range. It also seems to idle very ruff. I could not figure it out so I took it to a local shop to diagnose because it would not throw and codes and still has not. They told me it was a bad injector and I had them replace it (total $380 for diagnostic and parts/labor) When I picked it up it was EXACTLY the same. I drove it right back to them and they had it for another day and then when I went to pick it up they said that all they could say is that it seems to have too much EGR flow and thats what they think it is.. They swear up and down that I had a bad injector as well but I notice no difference at all, the mechanic actually told me "I would just ignore it".. So $380 spent and im back to square one.. I will never return or recommend that shop to anyone ever again.

Typically I work on my own vehicles, this is the first time ive had to take any vehicle to a shop to have them diagnose the problem because its not throwing any codes so I didnt know where to start. I have a code reader and could have saved myself some money if it would have just thrown a code.

It seems that the idle is getting worse, and the stumble at low rpms is still there if not worse. Today I pulled the vacuum hose going to the EGR and put a hose on it and sucked and the engine almost died, so it seems the valve is working properly. I left the vacuum hose disconnected and slowly revved the engine and the stumble is gone! I also noticed that there is a buzzing noise coming from somewhere very close to the EGR when I turn off the engine, which lasts for about 10 seconds and slowly fades away.

Im thinking that there is defiantly something not right either with the valve or the sensor that controls it but im not sure, still no codes and its so bad that it really should be throwing a code. Can anyone point me in the right direction?

 

Sounds like to much EGR flow. That can result in misfire, which is most likely why he went for the injector. That said, the mechanic is very inexperience with these engines. The injectors very rarely go bad and I honestly doubt that was a problem.

The buzzing noise after shutdown is normal and is coming from the EVR (your EGR vacuum supply). It's a solenoid with a white vac supply line and then green out to the EGR. Rest your hand on top of it while it's making the noise and you'll notice it vibrating, - like I said that's normal.

If you disconnected the green line from the valve and the vehicle ran okay, it's the EVR causing the EGR to remain open when it's suppose to be closed. This will cause your problem and by your explanation, IS your engines problem. By removing the Green line and the engine returning to normal operation has determined that. Replace the EVR Solenoid and disconnect the green EGR line until you do.

 

This sort of explains it. The PCM commands the EVR to open the EGR upon command. Vacuum is somehow getting by the EVR, supplying the Green EGR line constantly which is keeping the poppet valve open and causing the condition.

 

Thats the kind of info im looking for! thank you so much for that it makes sense! Wish I could pull the money spent from the mechanics pocket and put it in yours lol..

So I could run with it unplugged untill its replaced and it shouldnt hurt anything? will it throw a code then do you think and I should just ignore it untill the fix is done?

 

It might throw a code, might not. If you get a CEL after pulling it, then that's most likely why. Your mileage/economy may suffer a little bit until it's fixed. Plug the green line with a golf T or whatnot after you pull it. No, it won't hurt anything, it's hurting the way it is lol.

 

Replaced the EVR and problem solved!

 

Good Job

 

This might work for my problem too.
Thanks for the post