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Damn you Lotus!


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:beer:

As some of you may remember my thread about testing the system for boost leaks. Well everything was good up to 4psi with my hand pump. Well after my last dyno numbers being a little lower than I expected, I decided to test the system using a compressor @ 15psi. Well that didn't go well. I noticed I was losing alot of pressure out of the EGR pipe.

So I pull the plenum and checked the EGR valve. The EGR valve is fine but the design is LAME!!!!!!!!!!!!!11111111111111111111.

The piston on the EGR valve is on the pressure side so any positive pressure blows the piston open and lose pressure into the exhaust manifold. So all V8s leak. No wonder the stock turbos are so overworked. I also found my EGR pipe cracked but I guess thats "common" too!!!

:)

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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Hi Dave. I ended up installing a block off plate between the EGR valve and the plenum and another plate at the exhaust manifold. I have no CEL and the car runs great but best of all, no boost leak. Later, I scanned the car to see what the emission readiness monitors were doing. Turns out, Johan's ECU does NOT support EGR. So it was useless in my car anyways.

As for the EGR valve, it begins to leak at a pressure difference of anything over 5psi. A few days ago, I tested a 98 V8 with the High Tq ECU and it leaked also; no surprize there. My 5gal compressor could not pressurize the system more than 5psi (same as mine). The more the compressor would supply, the more it would leak.

Now, we may block it on this car to see if we get any CEL's because the High Tq ECU DOES support EGR unlike my ECU.

Edited by gmendoza

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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Hi Ganzalo,

A most interseting test result! Lets give Lotus credit for good engineering for a moment. That means in Lotus's testing they always saw less that 5 PSI deferential acrossed the EGR valve. Since the spec for any stock ECU is .75 bar or 10.8 PSI relative, that means there would be 10.8 - 5.0 = 5.8 PSI minimum of pressure allowed in the EGR pipe from the exhaust manifold at maximum boost. Seems high, but maybe. With higher boost you would need higher back pressure to keep the EGR closed. Lets see with a 2 bar absolute map semsor, a hole in the EGR pipe and a one channel Innovate recorder, we would know. A spacer plate between.... ah never mind. Anybody ever measured or have a sense of this??

Wayne

The Older I get the Faster I was

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I'll give you that Wayne. Lotus designed it to be just enough for the stock application. Although you lost me with your idea for a test. Are you suggesting a video of actual EGR operation and/or measuring back pressure?

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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Use a 2 bar GM map sensor, build a spacer plate (1/4") with a port on it, to go between the EGR pipe and the exhaust manifold. attach a line between the new port and the map sensor, supply the map sensor with regulated 5.0 Volts from the ECU and use a one channel innovate data logger to record the voltage. It would provide a direct read of the pressure in the exhaust manifold. Compare time stamps to the OBD-2 scanner stamps to track rpm & boost and you have it. No sure how long the map sensor would last with hot gases going into it, long enough for 1 or 2 runs, their cheap!

Wayne

The Older I get the Faster I was

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  • 4 weeks later...

This would also lead to an improper afr reading from the o2 sensor.. it would read lean.. which would make the car run even richer than the already ridiculous afr... wow.. Gonna go block egr now :)

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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  • 2 weeks later...
  • 4 weeks later...

Did this actually improve your power?

Leaking into the manifold shouldn't be an issue on a running engine as the pressure in the exhaust manifold should far exceed the boost pressure. I'm going to have a close look at my EGR as I have the engine out for repair and modification.

Edited by 97-Esprit V8
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I haven't scheduled a dyno yet because I was rebuilding the gearbox but the car does feel good.

Although I don't believe there is more pressure in the exhaust than the intake. If there was, then the stock 5psi wastegates would get blow open way before the car achieved 11psi of boost.

Dave, any update on your CEL?

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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When you guys are blocking off the EGR valve are you:

Are you blocking the EGR off and leaving it off the car completely and disconnected from the computer?

Also are you removing the air injection lines and the little vacuum combi valve on the back of the LH cylinder head?

Edited by Rgardner01
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I haven't scheduled a dyno yet because I was rebuilding the gearbox but the car does feel good.

Although I don't believe there is more pressure in the exhaust than the intake. If there was, then the stock 5psi wastegates would get blow open way before the car achieved 11psi of boost.

Dave, any update on your CEL?

The exhaust pressure should be near twice what your intake pressure, this is pretty standard (2:1 ratio), obviously it will vary design to design. Certainly the EGR will have more pressure on the exhaust side so the test you did doesn't replicate running conditions.

This about how the turbo works, kind of hard to have less pressure on the side that drives the compressor.

Edited by 97-Esprit V8
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Rey,

When I blocked mine off all I did was pull the pipe running from the turbo housing to the valve under the plenum and put in blocking plates on those 2 locations. I did not pull the valve or any other wires or lines. I saw no real need to pull the rest and it will make it easier to cobble something together if I ever have an emission issue when testing.

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When you guys are blocking off the EGR valve are you:

Are you blocking the EGR off and leaving it off the car completely and disconnected from the computer?

Also are you removing the air injection lines and the little vacuum combi valve on the back of the LH cylinder head?

All I did was installed a blocking plate at the exhaust manifold and another between the EGR valve and plenum. I left everything else connected.

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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