Technical EGR System - do I need it?

[andrewb]

My 1995 1.6 8V cabriolet has the Exhaust Gas Recirculation system. I know it's there to reduce emissions, but I can't help thinking that feeeding exhaust gas into the inlet manifold is reducing engine power and fuel efficiency. I'm thinking about removing the interconnecting pipe and blanking off the ends to see if there is a noticeable improvement in performance and economy.

If anyone knows more about this than me (wouldn't be very hard) and thinks it's a bad idea, let me know.

Punto Cabrio with holy roof, Multipla with child seat and Baby on Board sticker.

 

[Tziallas]

Hello there

The car manufacturers use Exhaust Gas Recirculation (EGR) to reduce emissions and specially NOx emissions.

The power that you loose with EGR is dependind with the percentage of exhuast gases comming back. With EGR about 5% you loose 2% power but you reduce NOx emissions by 15%-20%. EGR percentage is normally around 1% to 5%, there is not a point have more because the power drop is large compared with the emmision drop.

Now if you care about the enviroment a 2% power drop is nothing compered to what you gain in emissions, if you are a purist and you want every hp then you can remove the system but watch out in the MOT test, you may fail.

Reliability wise you do not gain or loose anything.

In a case like yours (90hp engine) you can gain 1-2 hp and may fail in MOT. For me it does not worth doing it...for you I dont know

 

[Evil-Punto]

There would definately be a change in performance. For a start the car would cut out every now and then when you coast, sometimes it'd run really rough and have no power.
The ECU tells the EGR to open and close, it then measures the lambda sensor readings, if the pipe was blocked or capped the readings wouldn't change and the ECU would show a fault and try to compensate. This usually stalls the car.

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Evil-Punto AKA Evilution.

 

[andrewb]

The lambda sensor measures the oxygen content of the exhaust gas. The major factor affecting this is the Air/fuel ratio, the ECU uses the lambda reading to control the air/fuel ratio. The amount of exhaust gas being recirculated probably doesn't have much effect on the lambda sensor reading. The EGR valve only operates between 1500 and 6000 rpm, so disabling the EGR system won't affect the tickover.

It's more likely that the symptoms described by evil-punto are caused by the EGR valve being stuck open, if they have anything at all to do with the EGR system.

Anyway, I made myself an aluminium blanking plate last night and fitted it under the EGR valve. The car was fine going to work today, and I'm most interested in how this mod affects fuel consumption, so if I remember, I'll keep you posted.

MOT is due soon so I'll find out if I really need it.

Punto Cabrio with holy roof, Multipla with child seat and Baby on Board sticker.

 

[whitey]

good on ya for givin it a try mate

i can see where evil is coming from on this one, as would disconnecting it not mean that the ecu reads it as being blocked/stuck. i mean, as far as the ecu can tell, it's just the same?

wake up and see the light! www.puntoforum.co.uk

 

[andrewb]

The ECU gets feedback from the EGR valve itself, so it knows what position the valve is in. There is a map which says what position the valve should be in for any given engine speed and throttle angle. On my car the valve is still there so the ECU is still happily moving it up and down. All I have done is block off the supply of exhaust gas.

Don't try this at home kids, it may be against the law!

Punto Cabrio with holy roof, Multipla with child seat and Baby on Board sticker.