egr delete, or keep?

[Brian]

I’m in hypothetical mode here, so be patient with me please. I have a 97 Camry 4 cylinder auto. I’ve cleaned the egr and I know its fine, but I’m still getting a code for it. I’m about to replace the downstream 02 sensor too. I’m sick of all that trashy exhaust carbon building up and I’m curious about just deleting the egr. I imagine the engine will run without it, but will it hurt my mpg? Will it forever throw a code if I do? I’m leaning backward thinking of domestic autos from the 70’s & 80’s when they had air pumps. Those things were supposed to increase mileage, but hurt it instead. Every time I deleted one of those, the car or truck ran way better. Your thoughts?

Topic

[Bryan]

Couple issues here…

1) If you delete the EGR, you’ll fail inspections if you have them.
2) You’ll almost definitely toss a CEL, so that’ll be permanently lit.
3) You’ll absolutely fail a sniffer test.

Basically, emissions is there for a reason… and removing it is illegal. You also generally don’t get a lot out of deleting it, so I’d just leave it be. Sure, you’re throwing a code now (or might be), but that can be resolved with a bit more effort and troubleshooting.

Just my .02.
-Hinoki

[Bluesnut]

I think there is some placebo at work here. A correctly operational EGR or air pump system will not cause a poor running engine unless there’s a problem with the system. To delete an EGR or remove the belt from an old air pump can be a problem although I’m fully aware it was done a lot.

Other than agreeing with the comments about the likely problems there is one that is far more serious. The EGR prevents pinging and with no EGR it’s possible for the engine to be destroyed if the pinging is serious enough and lasts long enough.

That’s an expensive gamble and my suggestion would be follow a proper EGR diagnostic chart, track down the problem. and repair it.

[Lorrin Barth]

Having run a turbocharged car with EGR delete I am doubtful of the danger of detonation. The biggest problem would be the CEL permanently lit.

My guess for the reason the EGR is throwing a code now is plugged passages in the head. What the valve has is a sensor checking for heat. No flow, no heat.

[Bluesnut]

I don’t think that a blanket statement that an inoperative EGR will not cause engine damage can be applied in every situation. I’ve torn into wiped engines that died from pinging due to any number of reasons. I’ve even bought a few cars on the cheap that had damaged pistons and cylinder heads due to pinging when the customer had no desire to wade into it for 4 figures and chose to dump the car.
One of them was an immaculate showroom clean Subaru with 70k miles on it and I picked that baby up for 700 bucks with one trashed piston and 2 partially trashed ones. To the customer a big expense; to me not so big and I got 13 years of use out of that car after fixing it.

My youngest son until recently had a Toyota Camry with a clogged EGR system and it was an accident waiting to happen. The slightest touch of the pedal at highway speeds and especially on upgrades gave me the creeps just to listen to it. There is no way on Earth that kind of clattering is good on any engine. Once I Roto Rootered the EGR passages out all was well.

[Lorrin Barth]

I don’t remember reading that exhaust gas recirculation was ever intended as a means of combating knock. Its invented purpose, as I understand it, is to reduce the amount of NOX at the tailpipe. Introducing exhaust gases into the combustion chamber lowers the combustion temperature and since more NOX is produced as temperature is increased this crazy scheme is said to work. That it will also cause rough running in certain engine regimes requires use of a valve, either vacuum actuated or now under the control of the engine computer.

Now, I don’t like the idea of defeating emission equipment. Where I live the air is clean and I wish it to stay that way. But I did block off the EGR on a car I owned but actually it was already pretty much blocked by the accumulation of carbon. I wasn’t about to clean it until I had other reasons for tearing down the engine. That never occurred. The engine had a knock sensor and I never heard a single ping. But that is just one engine. However I do know that this is a popular modification to high performance engines by the car modification people but it is hard to tell if this causes ill effects because many of them blow engines regardless.

So, anyway, what you say about the Camry surprises me but then I am always learning. Did this vehicle have a knock sensor?

[Bang Klas]

Thank you for being so detailed.

[Author]

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