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Discussion Starter · #1 ·
Ok, so at the recommendation of my "mechanic" friend, I blocked off my EGR valve. I have no emissions testing, no cat, and I was getting intermittent code 51s. Just drove the rig 80 miles with no problems, no real difference in drivability or mpg. Will I be hurting my engine at all leaving the EGR closed off?
 

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The codes will reappear.

Clean the egr, clesn the easily reached paths, and never look at it again.

Instead of your valves lasting 300k miles, they eill ladt 299k miles....realistically.

But it does gain you another half mpg if it works.
 

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Aside from emissions - and it appears that much of the US no longer cares about this - the EGR is supposed to make your valves somewhat cooler, as the cooler exhaust gas is recirculated. Many people disconnect the EGR purposefully. But your car also has the thermoprobe on the EGR valve, which should cause the code 51 to come back again, I imagine.
 

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You won't see much difference if your EGR was faulty. The EGR improves part throttle efficiency so it will work better with it.
 

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Discussion Starter · #5 ·
Without a catalytic converter on my vehicle, my EGR would never function properly anyway right? Cause I've cleaned it a couple times, and all the other ports (each time there wasn't much buildup) and my CEL will come on now and again with code 51.
 

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If the stall tests works on your car, then the passages are fairly clean and should be ok - there is more to the EGR system than just the valve - there is the VSV that controls vacuum, the hoses to it, the EGR modulator that applies the vacuum to the EGR valve, as well as the thermoprobe in your car that relays the temperature (through voltage) to the ECU, the thermoprobe wiring, etc. Any one of these areas can cause that temperature/voltage reading to be off so that the ECU throws the code. If your stall test passes, then the passages are usually clean enough, and you need to start looking elsewhere. Frankly, if your CEL comes on now and again - as in intermittently - I probably would look at wiring connections first.
 

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The EGR Transducer has to see some back pressure from the CAT to function correctly and without a CAT, the EGR valve won't open. As a result, combustion temps will be higher and NOX will go way up. The CEL will remain on until you correct the issue or remove the lamp.
 

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The EGR Transducer has to see some back pressure from the CAT to function correctly and without a CAT, the EGR valve won't open. As a result, combustion temps will be higher and NOX will go way up. The CEL will remain on until you correct the issue or remove the lamp.
The EGR is usually tested on deceleration when there is no back pressure but high intake manifold pressure. Normally there is enough back pressure from the muffler to allow the EGR to work. In many countries these engines don't have an EGR so the higher valve temperatures aren't really an issue.

MPG will be a little worse because the engine will be less efficient at part loads.
 

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The EGR is usually tested on deceleration when there is no back pressure but high intake manifold pressure. Normally there is enough back pressure from the muffler to allow the EGR to work. In many countries these engines don't have an EGR so the higher valve temperatures aren't really an issue.

MPG will be a little worse because the engine will be less efficient at part loads.
This may be correct for countries outside of the US, but on OBDII (96-98) vehicles, the EGR valve is closed on deceleration and only operates when there's ported manifold vacuum available (open throttle plate) and adequate exhaust back pressure. The EGR Transducer has a diaphragm that only allows vacuum to go to the EGR valve diaphragm when exhaust pressure is applied to it. The EGR also doesn't function during full throttle acceleration.
 

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Discussion Starter · #10 ·
So will I ever get my EGR function properly w/o a cat?
 

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So will I ever get my EGR function properly w/o a cat?
I'm not that familiar with the OBDI system to know if your EGR valve will open without a CAT, but I doubt it, because it takes the added back pressure of the CAT. The ECM uses the MAP sensor to determine the pressure differential when the EGR test VSV runs. It only runs for a couple of seconds each run cycle to compare the exhaust back pressure and vacuum available.

Pull the large hose going to the EGR valve and start the engine. There should be exhaust gas coming from the large EGR pipe. If there isn't, the port going through the head is clogged.
 

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This may be correct for countries outside of the US, but on OBDII (96-98) vehicles, the EGR valve is closed on deceleration and only operates when there's ported manifold vacuum available (open throttle plate) and adequate exhaust back pressure. The EGR Transducer has a diaphragm that only allows vacuum to go to the EGR valve diaphragm when exhaust pressure is applied to it. The EGR also doesn't function during full throttle acceleration.
Its correct for the US as well, the EGR is tested on deceleration by opening momentarily and checking for a change in manifold pressure, the test is done during deceleration because the manifold pressure is high and because it doesn't affect the running of the engine.

Heinz what muffler are you using?
 

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So will I ever get my EGR function properly w/o a cat?
Mine does.....there is some question about the amount of backpressure needed, and frankly, it appears to be small enough that you get this from the muffler anyway - not necessarily from the cat. The EGR does not work during idle, wide open throttle, etc. If you have one of those high flow mufflers, it may affect the EGR, causing the code. But I also believe that the code can be thrown for a faulty thermoprobe, vacuum leaks in any of the hoses in this system, faulty EGR solenoid, clogged EGR modulator, etc.
 

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Discussion Starter · #14 ·
EGR UPDATE.....tossed a 4k7 resistor across the thermoprobe connector, cut some aluminum and blocked off the EGR completely, and my rig is running better than ever. Even getting 2-3 more mpgs. I'm done messing with that damn thing! I'll let y'all know if I develop any problems from this "fix". Have a great weekend everyone!
 

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After finally getting all of the crap out of my low mileage (yeah right) motor...my egr functions. That is with headers, 2.25 in piping to a hiflow caf and magnaflow exhaust. Given the design of a magnaflow, a straight shot, it appears very little back pressure is needed....if any.
 

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EGR UPDATE.....tossed a 4k7 resistor across the thermoprobe connector, cut some aluminum and blocked off the EGR completely, and my rig is running better than ever. Even getting 2-3 more mpgs. I'm done messing with that damn thing! I'll let y'all know if I develop any problems from this "fix". Have a great weekend everyone!
Hi mate, did you just wire this in line? And issues afterwards?
 

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CADS, you are late for the game, the last entry was May 17, 2014
 
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Hi mate, did you just wire this in line? And issues afterwards?
Much of this depends on what vehicle you are driving (put your specs into your signature so everyone knows, please). The US Federal Trackicks had a thermoprobe inserted into the EGR valve in 1994-95, which was connected to the ECU, and would give a signal to throw the code 51. The California cars always had this thermoprobe. If you don’t have the thermoprobe sticking out of the EGR valve, then the resistor set up is unnecessary. On 1989-1995 cars, other than those with the thermoprobe, you won’t get a code 51, even if the EGR circuit is dead - it’s not connected to the computer.
 

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Apologies - vehicle is early 2012 GV 1.9L F9Qb, completely standard, Australian delivered model.

It has a cooked egr cooler, seeing communication between exhaust and coolant, so coolant lines have been plumbed to recirculate.

Honestly looking for the cheapest way out.
I've read that a blocking plate with a small ~4mm hole is enough to create some increased impedance on the temp sensor so as to avoid throwing engine codes.

I'd be interested in an in line resistor if its an easy enough job
 

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Well, to start, you’re on the wrong side of this forum - this is only for 89-98 Sidekicks/Vitara. You may get help if you start and thread over here. Your engine is completely different than what we’re dealing with over here. Spec out your car, as well as the market for it. You should get help on that side of the forum:
 
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