EGR Cleaning Mega-Thread
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EGR Cleaning Mega-Thread
First question. Has anyone used a good gun or pipe cleaner to clean out the EGR plate on the back of the head? Are there any liquid chemicals you can use to clean it out without scrubbing the thing? Anything you can do on the engine while driving?
Second, is there a way to test the EGR tempoerature sensor? I don't have my FSM handy as I'm at work, but this problem is bothing me. I'm getting a code 71 that keeps coming back after resetting the ECU.
I have removed and cleaned the temp sensor on the throttle body. There is another sensor of some sort on the EGR valve. What does that do, and can it be tested or replaced?
Second, is there a way to test the EGR tempoerature sensor? I don't have my FSM handy as I'm at work, but this problem is bothing me. I'm getting a code 71 that keeps coming back after resetting the ECU.
I have removed and cleaned the temp sensor on the throttle body. There is another sensor of some sort on the EGR valve. What does that do, and can it be tested or replaced?
Last edited by DupermanDave; 02-17-2010 at 11:10 AM.
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Dave, I have been contemplating an EGR system overhaul (you know after 280k it can't be working like new) as well and am interested in what you find out. There's a link to an FSM somewhere...
I have a 88 FSM and it shows a gas temp sensor on the california vehicles only but has no info on checking its operation.
I have a 88 FSM and it shows a gas temp sensor on the california vehicles only but has no info on checking its operation.
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Dave, I have been contemplating an EGR system overhaul (you know after 280k it can't be working like new) as well and am interested in what you find out. There's a link to an FSM somewhere...
I have a 88 FSM and it shows a gas temp sensor on the california vehicles only but has no info on checking its operation.
I have a 88 FSM and it shows a gas temp sensor on the california vehicles only but has no info on checking its operation.
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i used carb cleaner and picks but could not get the valve to break loose to move freely under vacuum. carbon is caked in so bad that it has sealed itself. you might just need a new egr valve if it isn't working properly. mine was stuck open so i have to eventually replace it. it is blocked off for the mean time.
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No do not believe that the valve is rubber. The transducer does have a rubber diaphram, but if it were torn it would not open. I also have the same 71 code on a Corolla, I know not the same but simular. The code you have I understand is part of the EGR system. I have verified that the EGR is working with a vacuum pump, killing the engine, so I am down to the EGR temp sensor as well. It could be as easy as checking its resistance, but dont have the specs. I was also wondering if perhaps adding some SeaFoam to the gas tank would help remove some of the carbon deposits that have accumulated over the years. Maybe someone here has more info or experience with this.
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No do not believe that the valve is rubber. The transducer does have a rubber diaphram, but if it were torn it would not open. I also have the same 71 code on a Corolla, I know not the same but simular. The code you have I understand is part of the EGR system. I have verified that the EGR is working with a vacuum pump, killing the engine, so I am down to the EGR temp sensor as well. It could be as easy as checking its resistance, but dont have the specs. I was also wondering if perhaps adding some SeaFoam to the gas tank would help remove some of the carbon deposits that have accumulated over the years. Maybe someone here has more info or experience with this.
Does the code 71 affect engine performance, or is it just a warning to the driver?
Last edited by DupermanDave; 02-19-2010 at 06:39 PM.
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#8
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I used a pistol cleaning kit on my old EGR valve (non-sensor type). The gun cleaning solvent worked pretty good at dissolving the crud inside. I tipped the EGR up on end so I could fill it w/ solvent, then let sit for a few hours before hitting the insides with the small round brush. Drain and repeat as needed and then used a hand vacuum pump to pull open the valve to let the solvent get in there. Seemed to work better after the cleaning.
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I'm ordering some gun brushes I found on amazon.com so I can clean the EGR better than I have been able to in the past.
Also, why does the engine stall or sputter when the valve is closed? Does it really make that much of a different for the exhaust gases to flow/not flow?
Last edited by DupermanDave; 02-19-2010 at 07:00 PM.
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Well could be a couple of cases. One is the ECU is commanding the EGR to open and it is not or it is plugged an exhaust gas is not flowing enough to heat up the sensor fast enough to tell the ECU the valve is open (if open, the hot exhaust gas heats up the sensor and that is what the ECU uses to confirm the valve is open). But it could be the the sensor is cakes in soot and not picking up the heat of the gas, or the sensor itself may be defective. In either of the last two cases, all is normal, EGR-wise, just that the sensor is not reading the right temperature. Some folks fool the ECU by jumpering the sensor connector with a resistor.
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As for the ECU reacting to the hotter engine temp, there is not really any feedback to the ECU. Many people have EGR block off plates and just increase the radiator size for cooling the engine block to prevent overheating. Just keep an eye on the temp gauge. Also dont know if you have to get a smog check out there, but NOx is a gas that is measured here in CA.
BTW the EGR is only open at cruise speeds between 40 and 60mph.
Last edited by boxer.fan; 02-19-2010 at 07:21 PM.
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I just checked by EGR by sucking on the vacuum line. I could feel and hear the valve opening and closing, but there was some grinding (guessing carbon buildup). Because I could feel the valve open and close, does this mean the EGR is okay?
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I was able to test the EGR by sucking on the vacuum line. I could hear and feel the valve opening and closing, though there was some grinding. I'm guessing because of carbon buildup. Does this mean the EGR is okay?
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I was able to test the EGR by sucking on the vacuum line. I could hear and feel the valve opening and closing, though there was some grinding. I'm guessing because of carbon buildup. Does this mean the EGR is okay?
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One test is to pull a vacuum on the EGR with engine at idle and see if the engine stumbles/dies. If so, that is saying that enough exhaust gas to kill the engine is getting through. But even that may not be enough for smog testing.
My '85 would kill the engine with opening the EGR, but it failed the NOx smog test as not enough gas was getting recirculated. I found in my case it was some internal soot buildup at the head to header and gasket area and I spent a few hours with a Dremel opening up those passages to allow maximum gas flow and them that dropped my NOx readings to about 1/3 of the original readings. I also shot solvent through all the internal passages and blew them out w/ compressed air. Basically made sure there were no restrictions anywhere and that let me pass smog.
#17
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For cleaning the rear cover plate, oven cleaner worked pretty well. Soaked, wrapped in a plastic bag, and left it for a day. Two days would have been better.
I used carburetor cleaner and some brushes for the EGR valve itself, being careful not to get any on the diaphragm up top. Hold the valve open to clean around its seat by either sucking on a vacuum line or using a pump if you're fancy.
I used carburetor cleaner and some brushes for the EGR valve itself, being careful not to get any on the diaphragm up top. Hold the valve open to clean around its seat by either sucking on a vacuum line or using a pump if you're fancy.
Last edited by flyingbrass; 02-23-2010 at 07:14 PM.
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For cleaning the rear cover plate, oven cleaner worked pretty well. Soaked, wrapped in a plastic bag, and left it for a day. Two days would have been better.
I used carburetor cleaner and some brushes for the EGR valve itself, being careful not to get any on the diaphragm up top. Hold the valve open to clean around its seat by either sucking on a vacuum line or using a pump if you're fancy.
I used carburetor cleaner and some brushes for the EGR valve itself, being careful not to get any on the diaphragm up top. Hold the valve open to clean around its seat by either sucking on a vacuum line or using a pump if you're fancy.