So my check engine light has been coming off and on for a couple years now but since all my driving has been in town I just ignore it because it is code 71 (EGR). Well, in August I am going to have to drive 5000 miles round trip. My concern is that with the long distance of cruising, my engine will be running too lean and I will hurt something. I've taken the EGR off and it was not clogged. My head was off approx 30,000 miles ago for a head gasket and it got cleaned. Has anyone ran long ditances with the EGR malfunctioning and/or blocked. I'm wondering whether or not to try and deal with it before I leave or not. I've also read about adjusting the AFM and was thinking maybe adjusting it one click to prevent it from running lean, but during my searches I found a lot of DO NOT TOUCH IT responses. I've also read where people put in a restrictor plate that reduces the amount of gases and was wondering if anyone's had success doing that with a header installed and 2.25" exhaust as I have. Or would I be just as well blocking it off.

does it have CALI emissions? if so id check the egr temp sensor located on the top of the egr pipe at the intake manifold

Your EGR essentially reduces the displacement of your engine by bleeding a little exhaust gas back in to the intake. The effect is that the fresh air coming in to the engine is diluted, causing a lower ratio of oxygen to burn. In response, less fuel is added to prevent a rich mixture. On a long trip, this can cause a significant mileage increase. It also reduces the combustion temperature, the desired effect is to reduce harmful emissions caused by high burn temps, but also prevents burning your valves. So having a working EGR system, especially on a long trip, could save you money (fuel) and prevent serious engine damage.

I don't know which system you have specifically, but here are some basic tests. With the engine idling, attach a vacuum pump to the EGR and apply vacuum. The engine should stumble or die. If it doesn't, either the diaphram is ruptured (won't hold vacuum) or the ports are restricted (very common on the 22R. Unfortunately, to clean them out, you need to remove the head).

If it does stumble or die, you have a control or feedback problem. Your EGR may be working fine, and just isn't registering properly. Ford uses a DPFE sensor that reads the exhaust pressure drop across a fixed orifice during EGR function. Most often, an EGR code on a Ford is a bad sensor, not the EGR. GM monitors EGR flow by reading the MAP sensor. EGR function has a direct effect on engine vacuum.

Any way about it, in the 18 years I've been fixing cars, I've seen a lot of disconnected EGR's. This is most often done by people who don't know any better, and think such things decrease performance. The fact is, there are no negative effects of an EGR, and plenty of advantages. I've changed many head gaskets that were burned hole-to-hole. Just finished one two days ago on an Isuzu. Any coincidence that the burn was between two exhaust valves? Not really. The valves were not burned, and the valve adjustments were correct. The EGR hose was disconnected, capped with a screw. Sadly enough, when connected, the system worked fine.

we all fear what we don't understand. that said, i've got 1 truck with a functional EGR valve, and one where the entire emissions system has been deleted. if the valve is working properly, there should be no difference in power, because it kicks off when you step on the gas for the most part.

What can be done when the test to make it stumble or die works but the check engine light still stays on. I have reset it a dozen times. When I pull that hose off and apply suction my motor stmbles, I have not been able to make it die this way thou. Any suggestions? Does the sensor just need replacing or since I cant kill it is there something clogging it just enough to trigger the sensor? Im tired of looking at that orange light.
Thanks

nice explanation tech. but i am guessing your egr is just stuck open or closed. from my experiences w/ my egr on my carbed rig, if its clogged, you will get pinging upon acceleration. so i dont think its stuck closed but try tapping it w/ a wrench or small hammer to see if it does anything.

Ive experimented around with bypassing my EGR system. Ive tryed plugging the vacume hose, and I once made a plate to block the passage. I recieved check engine lights both times very soon after. I imagined the EGR temp sensor wasnt reading any temp due to the blockage and sent me a code. To the best of my knowledge, the EGR temp sensor is the only thing that can really give you a code 71. So if your getting vacume to your EGR and the diaphram is opening, Id look at the sensor circuit.

By the way, I never noticed any increase in gas or performance with my EGR bypassed. Good explanation Tech.

Then it sounds to me as if the valve itself is OK. So either the control system is not able to supply vacuum to the valve or the feedback system is not sensing the change. I'll try to look it up on Alldata this week and let you know how your works, but I can't promise anything. We're a little understaffed right now, so I'm very busy. I've got a 55 Ford truck in right now with a Thunderbird 312, an Ofenhauser intake and three two barrels that my customer would really like to have back soon... he just picked up the intake and carbs. They look great, but leak badly and don't run worth a s**t.

Thanks for all the replies. No it's not a cali truck. Unfortunately I'm overseas right now and am unable to do any of the checks. I've just had a little down time lately so I've been thinking of things to do before I make my trip in August. I'm getting home in January and will be able to get into it again then. I'm not wanting to eliminate the EGR if I don't have to. I just don't want it running too lean for thousands of miles because it's throwing the code and doing catstrophic damage to the engine if I can prevent it. On the same note, I've read of people changing all the components and still having the issue. And since I don't think any of the parts are under $100, not a big fan of doing that. I plan on doing the checks in the FSM link from the board, which I think are what has been suggested. For now, everything is hooked up. Looks like I'll just have to wait until I get back to troubleshoot further. I'll keep this thread in my favorites and if I'm able to find a fix, I'll post an update with the steps it took. Thanks again for the feedback.