EGR circuit
- Thread starter V
- Start date
The_Bronze
Donating Member
Re: EGR circuit
Interesting thought. As a guy who is going to start tuning once I can hang a radiator, I'm watching to see the possibilities.
:comfy chair smiley:
opcorn2:
Interesting thought. As a guy who is going to start tuning once I can hang a radiator, I'm watching to see the possibilities.
:comfy chair smiley:
opcorn2:
sytyguy
Moderated User
Re: EGR circuit
Are you wanting to wire something up with the EGR circuitry and drive/control it with the EGR code? If so, look into the EGR code heavily....make sure it fits your needs for control, as it's not the most accommodating code for controlling things under all conditions (think of how/when EGR operates on a stocker).
Are you wanting to wire something up with the EGR circuitry and drive/control it with the EGR code? If so, look into the EGR code heavily....make sure it fits your needs for control, as it's not the most accommodating code for controlling things under all conditions (think of how/when EGR operates on a stocker).
V
Donating Member
Re: EGR circuit
Right now, I don't have a specific goal. I'm looking for tinkering ideas. The location of the EGR circuit (near firewall, downpipe and turbo) just makes me think that it is a prime candidate for code tweaking. I've had some of the same ideas as Mike, but I wanted to see what else is out there. If others have already modified the EGR code, their experience might give us a better idea of what else can be done.
Right now, I don't have a specific goal. I'm looking for tinkering ideas. The location of the EGR circuit (near firewall, downpipe and turbo) just makes me think that it is a prime candidate for code tweaking. I've had some of the same ideas as Mike, but I wanted to see what else is out there. If others have already modified the EGR code, their experience might give us a better idea of what else can be done.
The_Bronze
Donating Member
Re: EGR circuit
Without the tuning insight...
Typical failure for GM egr is that the Map sensor sees an increase with throttle tip-in. When the MAP increases, the EGR solenoid is opened, and vacuum flows, but without enough backpressure to allow the valve to open. As the EGR spring degrades, often times the EGR opens due to the weak spring and causes "my truck starts fine, but once I touch the throttle, it runs like crap at idle and dies". Pull EGR hose and see if it runs right. If it does, replace the EGR valve. Done it a hundred times. I've scoped it a bunch of times as well and it's clear that the MAP rises and immediately AFTER the EGR solenoid electrically is triggered on and then off with the touch of the pedal. With a bad EGR The EGR stays on because once the EGR is turned on momentarily and the EGR come on early the MAP stays low and the engine keeps EGR on because it thinks it should. A vicious cycle.
With that insight, I was thinking along the lines of factory meth injector control through the PCM. It's load based- you probably can control the duty cycle compared to MAP (load). My question (I have the tuning equipment for my rig, but the rig is getting bodywork done and no radiator to run it) is this: Does/Can the PCM call for increased EGR dutycycle throughout the load range, or is there a programming stop for high loads (EGR is automatically disabled by lack of vacuum, but I never checked to see if the EGR is still controlled on electrically)? Just a thought for incorporating alcohol injection delivery via the factory PCM. If it turns it off at higher loads and cannot be maintained or increased, then its seems useless for that application.
Without the tuning insight...
Typical failure for GM egr is that the Map sensor sees an increase with throttle tip-in. When the MAP increases, the EGR solenoid is opened, and vacuum flows, but without enough backpressure to allow the valve to open. As the EGR spring degrades, often times the EGR opens due to the weak spring and causes "my truck starts fine, but once I touch the throttle, it runs like crap at idle and dies". Pull EGR hose and see if it runs right. If it does, replace the EGR valve. Done it a hundred times. I've scoped it a bunch of times as well and it's clear that the MAP rises and immediately AFTER the EGR solenoid electrically is triggered on and then off with the touch of the pedal. With a bad EGR The EGR stays on because once the EGR is turned on momentarily and the EGR come on early the MAP stays low and the engine keeps EGR on because it thinks it should. A vicious cycle.
With that insight, I was thinking along the lines of factory meth injector control through the PCM. It's load based- you probably can control the duty cycle compared to MAP (load). My question (I have the tuning equipment for my rig, but the rig is getting bodywork done and no radiator to run it) is this: Does/Can the PCM call for increased EGR dutycycle throughout the load range, or is there a programming stop for high loads (EGR is automatically disabled by lack of vacuum, but I never checked to see if the EGR is still controlled on electrically)? Just a thought for incorporating alcohol injection delivery via the factory PCM. If it turns it off at higher loads and cannot be maintained or increased, then its seems useless for that application.
TYTILIDIE
METH HEAD
Re: EGR circuit
Guys like Dig, Jeff and Paul would be able to answer these questions I bet. Here are the tables, not sure what they do though, or how they actually work.
EGR Duty Cyle vs EGR Flow, EGR% is on one side and Duty cycle o0n the other. Second table is EGR Flow Pressure Compensation vs Pressure, KPa on one side and Flow on the other. Last table is Desired % vs Vac and RPM, looks like RPM going vertical on the left and Vac up top going horizontal. Hope that helps.
Guys like Dig, Jeff and Paul would be able to answer these questions I bet. Here are the tables, not sure what they do though, or how they actually work.
EGR Duty Cyle vs EGR Flow, EGR% is on one side and Duty cycle o0n the other. Second table is EGR Flow Pressure Compensation vs Pressure, KPa on one side and Flow on the other. Last table is Desired % vs Vac and RPM, looks like RPM going vertical on the left and Vac up top going horizontal. Hope that helps.
The_Bronze
Donating Member
Re: EGR circuit
There are a 14 constants and scalars for this as well. I put them all on the screen and it filled it up. Lots to play with, but I'm not there yet!
There are a 14 constants and scalars for this as well. I put them all on the screen and it filled it up. Lots to play with, but I'm not there yet!
sytyguy
Moderated User
Re: EGR circuit
One of the issues is EGR circuitry control under boost. EGR is conditionally, utilized for cruise situations, so for ideas that need control under boost, it may not be the best option (not that it can't be rewritten). Similarly, driving something simple (on/off such as a fan or pump) with it all the time would be like building a computer to operate the oven timer.....under utilizing the tools at hand (though for cleanliness/ease of removal sake, this might be optimal).
I'll be glad to help where I can. I have plenty of experience with the EGR control in the chip, though not much on the wiring/physical side of the EGR.
One of the issues is EGR circuitry control under boost. EGR is conditionally, utilized for cruise situations, so for ideas that need control under boost, it may not be the best option (not that it can't be rewritten). Similarly, driving something simple (on/off such as a fan or pump) with it all the time would be like building a computer to operate the oven timer.....under utilizing the tools at hand (though for cleanliness/ease of removal sake, this might be optimal).
I'll be glad to help where I can. I have plenty of experience with the EGR control in the chip, though not much on the wiring/physical side of the EGR.