Boost Relief Valve Questions

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Jan 14, 2005 | 11:46 AM

blackx psd

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From: Nebraska

Boost Relief Valve Questions

I have some questions about this. My setup is a 2000 Excursion which has 220,000 miles. I have the Napa 6637, Magna flow 4" stainless exhaust and the Superchip gold set at 100 hp mode. I am seeing the SES light.

I have read that when the computer shows this it defuels. OK understand that but if a person was to put the valve in-line with the map to disable the light. The computer is only going to read 23 lbs of boost but if the engine is actually running 28, won't the engine lean out too much?

I guess I am more confused than anything. I just don't want to lean the motor out. Any help on this subject will be appreciated. Thanks

Jan 14, 2005 | 12:23 PM

wlihntr

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From: colorado

Quote:

Originally Posted by blackx psd

at anything over about 22 psi the PCM will run the fuel system in "open loop" meaning it is sending all the fuel it can to the motor, so as your boost goes past that it 24psi the PCM will start to limit that fuel to back down the engine. when you put a a relief valve in the fuel flow stays at max up to what ever boost the engine will make. your chip will increase the fuel well over stock to help with those higher boost levels

Jan 14, 2005 | 12:47 PM

blackx psd

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From: Nebraska

If the engine is dumping the max allotment of fuel at 22, either the truck is running rich at that point or I will be running lean farther up the boost scale. Correct?

The boost relief valve is the same thing as a boost controller, right?

Jan 14, 2005 | 01:07 PM

wlihntr

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From: colorado

Quote:

Originally Posted by blackx psd

If the engine is dumping the max allotment of fuel at 22, either the truck is running rich at that point or I will be running lean farther up the boost scale. Correct?

you will be runing with less fuel and more boost father up the boost scale, instead of less boost and less fuel. one thing to remember is really cant use the terms "lean" and "rich" as it applies to gas engines in a diesel application. a diesel has no throttle like a gas engine, a diesel makes power by adding fuel and the engine, its allowed to draw in as much air as it needs.

Quote:

Originally Posted by blackx psd

The boost relief valve is the same thing as a boost controller, right?

no, it is a device to fool the map(manifold air pressure) sensor so it does not think the engine is making too much boost. a boost controller would go into the wastegate line so you could adjust when it opens and "control the boost". again, it may be nessary to put a boost controller in a gas engine so you can get the most boost you can without pre ingnition (detonation) but it does not really apply to a diesel, you want as much boost as you can get