No, GM advances timing based on %EGR valve is open.
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Is the EGR. Delete good
- Thread starter Shon350Hodges
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So if the PCW realises the EGR valve is disconnected it will cease advancing the timing (assuming the offset is to advance)?
I'm not sure what it does but, I would think it stops trying to advance timing and will throw the code 32.
But people say if the EGR is disconnected (without retuning) it will knock. Which implies that it continues to advance the timing irrespective of EGR valve being disconnected. Which is what I want as there's no danger of knock on octane #100+ of LPG and the absence of EGR will help speed up slow-to-get-going LPG combustion.
(I think I have the EML on - but it doesn't bother me as it goes out when I switch to LPG).
I've not heard that. When I had the EGR connected and it failed, I didn't get any KCs, just the SES light. When you stomp on the skinny pedal the EGR is closed by the ECM/PCM. GM's factory SA tables are very conservative. That's one reason why a "tune" will give you better performance by adjusting SA and VE tables, among other stuff.
someotherguy
Truly Awesome
I'm sure whether or not it will ping when failed depends on the failure mode.
If removed, which can easily be different operating parameters than failed (no EGR action at all vs. EGR action of inappropriate amounts/under incorrect conditions), you no longer have exhaust gas (essentially inert gas) helping to cool the combustion chamber, so you can be more prone to pinging.
Richard
If removed, which can easily be different operating parameters than failed (no EGR action at all vs. EGR action of inappropriate amounts/under incorrect conditions), you no longer have exhaust gas (essentially inert gas) helping to cool the combustion chamber, so you can be more prone to pinging.
Richard
That's a possibility. The reason I'm saying you shouldn't get pinging is I'm running HLC where I'm advancing timing as much or more than the EGR plus I'm leaning out the AFR more, and I'm not getting any KCs when cruising.
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I accept that overall combustion temperature will be lower with EGR than without. But initial (pre-combustion) temp will be higher as the EGR is uncooled (hot exhaust gas). This is known to promote ping in 2T engines (admittedly at high concentrations).
I'm more inclined to believe the reason for spark advance with EGR is to compensate for the slower burn rate that EGR causes. Again, referring to 2T engines, despite the increased tendency to ping when hot residual exhaust products are present, they still require significant spark advance to compensate for the lower burn rate.
All this assumes that the reason GM employ EGR is to cut NOx emissions - which makes switching EGR out at high loads an odd strategy - but is compatible with it being there to reduce part load throttling losses.
Illbedipped
OBS Enthusiast
How do you add HLC? Is that an ECM change or what?
Yep, what Service # ECM/PCM do you have? Some of them have been "hacked" by other "programmers" who then, add an option to add HLC in the "Mask" for that particular generation of ECM/PCM. Some came with it from the factory but, have been disabled due to U.S. regulations. Otherwise, you may have to build you own.
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