vacuum switch

[1987HondaAccord]

i was thinking about the egr vacuum/electrical circuit and i was wondering if you could have a switch, activated by the vacuum for the egr valve hidden in the black box? it would make the ecu think its working and any smog tests would pass cuz they wouldn't see the switch. maybe there's an easier way with just a relay?

i'm not exactly how the egr electrical circuit works, or how/when exactly the vacuum is applied.

any help or suggestions would be great!

[A20A1]

EGR has some uses to it, it acts against detonation, lowers emissions.

The thing is that the EGR valve has a sensor on it... so you may have to fool the sensor on the EGR valve... not simply apply vacuum.

I think those who removed the EGR valve,
1) Removed the EGR valve from the intake manifold.

2) Clean off the gasket material carefuly, you'll need it to trace a new gasket.

3) Make a metal gasket from the EGR gasket template, but do not cut out the rectangular hole in the gasket... you don't cut that hole because you want it to seal the rectangular port on the intake manifold.
The circular port is not sealed cause that is used by the EGR valve and sealing it may interfere with the valve operation which could cause the ECU to say there is somehting wrong with the EGR valve.

4) Bolt the EGR valve Back on the intake manifold.

5) All Vacuum and electrical connections remain on the EGR valve.

.
Since the rectangular port which feed the exhaust gas to the EGR valve is sealed the EGR valve wont intect exhaust gasses into the intake stream but the EGR valve will still be functional as far as the ECU is concerend.

[1987HondaAccord]

The thing is that the EGR valve has a sensor on it... so you may have to fool the sensor on the EGR valve... not simply apply vacuum.

that's right. I wanted to use the vacuum applied to the egr valve to activate a switch that would work in place of the sensor. would that work?

[A20A1]

Yeah I've seen turbo EGR units that have a intercooler like part to cool the gasses before reinjesting them. I dunno where the gasses were injected though, it would seem hard to inject it after the turbo into the charge pipes... but introducing it prior to the turbo would add carbon buildup to the turbo impeller and then the gasses would be reheated when compressed.

[joebeets]

The ECU does not know whether the EGR is working. It sends a vacuum to open once the engine is warm and rpms above some threshold. You only need to remove and plug the vacuum hose to defeat it, but it's not a good idea. It will encourage knocking and add oxygen to the exhaust, reducing your cat's performance.

[A20A1]

I thought EFI EGR had a lift sensor on it.

Carb cars don't.

[Oldblueaccord]

I thought EFI EGR had a lift sensor on it.

Carb cars don't.

you will get a code 12 i think but im not sure what its looking at. EGR would be at at part throttle but when it comes into play im not sure really and that be the trick to mimick that.


wp

[Blkblurr]

The efi's do have a lift sensor on them. I also think there is a pressure change expected when the egr is open and flowing. I know this is in later Accords. It is measured by the MAP sensor. Lack of flow detected by the lift sensor and the MAP sensor causes an error code. This happened on my 97 and 2000 Accords.

[joebeets]

The ECU does not know whether the EGR is working. It sends a vacuum to open once the engine is warm and rpms above some threshold. You only need to remove and plug the vacuum hose to defeat it, but it's not a good idea. It will encourage knocking and add oxygen to the exhaust, reducing your cat's performance.

Oops. My mistake. EFI has EGR feedback. If there's no EGR, the ECU will try to open it, but that's all. No need to substitute a bogus signal if the EGR is disabled.

[1987HondaAccord]

as i understand it, if the computer doesn NOT get a signal showing that the egr valve is open, it will thow a code. I want to avoid having that code constantly pop up.

[A20A1]

Thats why I suggested make a gasket to block the EGR gasses... the vavle will operate it just wont flow anything.

Swap the gasket when emissions comes around.