V8 Egr delete - LotusTalk - The Lotus Cars Community
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post #1 of 9 (permalink) Old 07-14-2019, 05:42 PM Thread Starter
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V8 Egr delete

hey techno guys - have to take my intake off and after much tado am going ahead with intercoolers and cooling system upgrades - figured it was time to delete the EGR system - what does one do with the ECu issue of trying to trigger the egr system - I am assuming that the ECU will make fuel compensation - also do i remove and blank off the EGR under the manifold ??? thanks any info would be appreciated
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post #2 of 9 (permalink) Old 07-14-2019, 08:11 PM
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Not much to be gained by deleting the EGR and unless you can modify the ECU so you don't generate error codes, it will just degrade performance. Before trying to "improve" the car, my suggestion is to get it running the very best you can. Then "improve" the driver by taking a driving course like Skip Barber. As for the ECU, just make sure it has the HTU firmware. An '03 should.
David Teitelbaum
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post #3 of 9 (permalink) Old 08-14-2019, 02:44 PM Thread Starter
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David - thanks - i am having clearance issues with the EGR tubing to the intercooler piping need 2" clearance- and Yes I agree learn to drive the car to the max before looking for more power and yes i already do - have a few yrs into SCCA road racing and 2 wheel racing as well -
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post #4 of 9 (permalink) Old 08-14-2019, 03:10 PM
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I removed the EGR as part of adding the air/water intercooler setup as well for the exact same clearance reasons you cite (if I knew how to paste a link to the thread in this forum on my efforts I would, but I'm sure you can easily find it).

The EGR recirc pipe is simply removed and the turbo outlet and manifold inlet are blanked. I left the EGR valve connected even though the inlet is blanked in case ECU wants to see current to the EGR circuit when actuated.

I run the HTU ECU and I'm surprised that I don't get a check engine light for the blanked EGR since there is a temperature sensor in the EGR valve that is supposed to confirm that exhaust gasses do indeed flow when triggered (to ensure you didn't do what we're doing). The EGR readiness flag seems to be near impossible to clear and it seems that this readiness flag is rarely set. Last time I went through the emissions check station the readiness flag wasn't set but it also wasn't tripped as a fault, so I passed the check. I have run years this way and it still hasn't tripped (nor cleared). Your state might have different requirements on all readiness flags being set or not.

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post #5 of 9 (permalink) Old 08-14-2019, 10:19 PM
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Originally Posted by ksgrimsr View Post
I removed the EGR as part of adding the air/water intercooler setup as well for the exact same clearance reasons you cite (if I knew how to paste a link to the thread in this forum on my efforts I would, but I'm sure you can easily find it).

The EGR recirc pipe is simply removed and the turbo outlet and manifold inlet are blanked. I left the EGR valve connected even though the inlet is blanked in case ECU wants to see current to the EGR circuit when actuated.

I run the HTU ECU and I'm surprised that I don't get a check engine light for the blanked EGR since there is a temperature sensor in the EGR valve that is supposed to confirm that exhaust gasses do indeed flow when triggered (to ensure you didn't do what we're doing). The EGR readiness flag seems to be near impossible to clear and it seems that this readiness flag is rarely set. Last time I went through the emissions check station the readiness flag wasn't set but it also wasn't tripped as a fault, so I passed the check. I have run years this way and it still hasn't tripped (nor cleared). Your state might have different requirements on all readiness flags being set or not.

Knut
Richard is in Canada (west coast) so there are no annual inspections, though it is odd that removing the EGR does not create flags

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post #6 of 9 (permalink) Old 08-15-2019, 08:58 AM
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I always thought the EGR recirculates exhaust gas back into the intake - this dilutes the intake charge - so the car wont run at peak.

An EGR valve is one of those emissions compromises that OEMs had to make for clean air compliance- Not performance.

I would not bother on my Camry but on an old performance sports car this mod is on the table, if I can do it with out getting cross with the inspections and completely tanking re-sale.

Its just one more sub system, to leak or fail and add weight, and in this case hurts performance a little.

Does an EGR only operate during cold start?

For me its the same concept as:

Air Pump (pumps air into the exh manifold, increases back pressure, reduces performance, emissions compromise, another heavy complex system to fail)

Crank Case breather - (dilutes intake charge, oil mist lowers octane, especially bad on turbo car, emissions compromise)

Removing these systems when possible has many benefits when combined with a tune can increase power and in some cases lower emissions (dont ask me to prove that, I read it on the internet :-))

I am a VERY green tree hugger guy. But I dont believer that a few old sports cars that are hardly driven make it worth maintaining these obsolete emissions systems that never worked that well to begin with. My county Emissions board agrees - they dont check emissions after 25 years.

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Last edited by Erik L; 08-15-2019 at 09:08 AM.
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post #7 of 9 (permalink) Old 08-15-2019, 10:40 AM
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The EGR (Exhaust Gas Recirculation) injects a very small amount of spent exhaust into the intake near the valve. The purpose is to cool (I know it sounds counter intuitive but that's what it does) the combustion so the engine produces lower NO2. There is no pump, it relies on exhaust pressure through specifically sized orifices, so it really doesn't affect performance much. It just effectively consumes a very small amount of space in the cylinder that could otherwise hold gas/air - think of it as the equivalent of a 5cc lower displacement. The EGR operates anytime the engine is running and there is exhaust pressure.

The air pump is to inject air just behind the exhaust valves. The purpose there is to help any unburned gasses to complete their combustion and lower CO. In that case the injected air makes no difference in the combustion power, it's the drag from the air pump itself that robs HP.

Neither was needed on the early HCI cars as the FI was clean enough to meet the regs without them.
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post #8 of 9 (permalink) Old 08-15-2019, 10:55 AM
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I think the air pump injects air into the exhaust and the air takes up "space" that could otherwise be exhaust. Its like having a 2 inch exhaust instead of 2.5 inch. Increases back pressure - less free flowing,

But the system adds air to the exh so un-burned fuel can burn in the Cat converter (as mentioned above).

My understanding is this helps a lot with older poorly maintained cars. A well maintained and tuned car wont have much extra fuel pouring out the exhaust to burn anyway.

I never thought about the drag the pump has. More weight, more heat, more failure points.

Of course, I also never thought that maybe the OEMs (especially on a performance car) size the exhaust for this air injection so there is no negative back pressure consequences. These are some smart folks.
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post #9 of 9 (permalink) Old 08-16-2019, 05:51 AM
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Manufacturers tended to learn over time. Most of us of a certain age remember the early 70's era smog choked cars that dieseled and produced feeble horsepower for what they were (180 hp large block V8 Corvette anyone?). By the time Lotus was building the Turbo Esprit the technology had come a long way in a decade, which is why the difference between Euro and US turbo engine power outputs wasn't that great. Removing all the Esprit smog stuff will give you a small HP boost but probably less than you think.
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