Egr Valve?

sreaminbronco · Dec 15, 2004

Went to the mechanic the other day because my check engine light was on. So he hooked the computer up to it and he said it was the EGR solinoid so i went to a for parts place and got one but it didnt do a dam thing so friday im going to replace the EGR valve but i dont know what it does and if its worth replacing.

Seabronc · Dec 15, 2004

If you have to pass emissions tests in your state, you have to fix the problem. The function of the EGR system is to reintroduce small amounts of exhaust gasses into the combustion cycle in order to reduce the generation of Nitrus Oxide.

Things that determine how much exhaust gas is recirculated are engine speed, altitude, engine vacuum, exhaust system backpressure, coolant temp, and throttle angle.

Your system should have a control solenoid, sensor and EGR valve. There may also be a sandwich cooler to reduce the temp of the recycled gasses, if so it will be between the valve and the intake manifold. The cooler helps the gasses flow better, reduces the tendency for detonation (commonly calld ping) and extends the life of the valve.

Another part of the system is vacuum, check the hoses to the valve which probably includes the hose to the vacuum reservoir and perhaps a check valve that needs to be functioning properly.

As you can see a code that says EGR is only the tip of the iceberg

. It takes a bit of investigation to narrow down the cause, or you can shotgun it with parts.

Other than the check light, do you have any other symptoms like rough running, surge, hesitation, poorperformance at part throttle? :unsure:

Good luck,

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sreaminbronco · Dec 16, 2004

the only other problem i have is bad gas mileage and hesitation to accelerate like when i slam on the gas it takes a lil' while before it accelerates

Seabronc · Dec 17, 2004

Both of those symptoms can be caused by the EGR valve. I would pull it off and look at the condition of it. They tend to get carboned up after a while and stick in one position or the other or don't fully close due to deposits.

Poor milage is sort of a fuzzy term when applies to a Bronco. Typical it is 10 - 12 MPG. Some get 12 - 15 but that doesn't seem to be the norm. They wern't designed with fuel economy in mind.

If you mean 8, 9 MPG. Yah, that is poor milage. So in the light of 10 - 12 you are gettig poor milage, that can be caused by restricted or no EGR flow. I would suspect restricted by carbon buildup, or a broken diaphram. You can take it off and use a piece of vacuum hose to test it. If you have a vacuum pump use it or suck on the end of the hose, just be carefull of inhaling some crap out of it, keep your tongue in the way so you don't have a strait shot down your throat. There shouldn't be any crap in the vacuum side but it's good to be careful.

Abnormally low power at wide open throttle can be caused by the valve being stuck open or the control solenoid not venting. Either will cause the EGR valve to be allowing gasses to be introduced into the system at the wrong time.

Looking at the overall symptoms, I'd say it sounds like the EGR valve sticking or not functioning at all.

Good luck,

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