A new twist to enable a 'psuedo lean cruise'?

[N0DIH]

Ok, if my understanding of EGR still holds (and I haven't studied for many years, so modern EGR may be operating differently), when EGR is enabled, timing is increased and AFR is decreased (leaner).

So, if I change what rpm EGR comes in at (say concentrate only on cruise rpm range I desire, say 1800 rpm to 2300 rpm), physically disable the EGR valve, and instead of INCREASING timing, decrease it slightly if needed, or just leave it zero degrees change, should force the AFR leaner (or does the nature of EGR flow make it leaner? I thought EGR was introducing inert gas) and potentially cruising slightly leaner.

Now, this is likely not emissions legal (unless your car doesn't come with EGR factory), but might be worth the evaluation...

Maybe like GM uses the Virtual Fuel Sensor, we can have Virtual Lean Cruise?

Ideas?

[dfe1]

Don't you have some LT1 work to do?

[GMPX]

Virtual lean cruise could be done using Custom Operating system version 3 because you can command any AFR at any MAP / RPM.

Cheers,
Ross

[N0DIH]

The beauty is you don't need a custom OS to do it. So ancient technology drivers like me have to "suffer" with the LT1 PCM and what I can do with it.

Hey, I am happy as a clam I got a new update to my LT1 Definition file today. Ask and you shall receive! John over at TunerCat is still updating things when requested. If the LT1 is still getting updated at all these years imagine what will be found and discovered in the L92 in 13 years....

[jpliss]

not to high jack but can you tell me a little about the TunerCat system? I have been looking at purchasing this for my LT1 apps. I would like to ask just what would I need to get? And how well does it work and how hard or easy is it to flash the ECM? You can either PM me or email.

Thank You

[GMPX]

John over at TunerCat is still updating things when requested. If the LT1 is still getting updated at all these years imagine what will be found and discovered in the L92 in 13 years....

Not trying to be rude, but didn't TunerCat get bought out by JET?

Cheers,
Ross

[N0DIH]

John sold the sales end to Jet for TunerCat OBD2, he is still the programmer. TC OBD2 was nice, unlimited vehicles for $300, $80 for each vehicle family (Definition file), if you have it he still supports it directly. But Jet had him VIN Lock it and they sell it now for $380 if you can find it, or $475 directly to Jet and some retailers like Summit and Jegs. Now only 4 vehicles and you have to blow away a VIN just to read now.

TunerCat OBD1 is still sold by John directly, as well as a bunch of his other programs for OBD1. He supports those programs quite well, and still is the #1 tuner for LT1's. No one else holds a candle to what he has still and is willing to update as needed. Even BLM locked and unlocking is there if you tune for that (I do, but it is something I won't do for others....)

[truethinker]

Ok, if my understanding of EGR still holds (and I haven't studied for many years, so modern EGR may be operating differently), when EGR is enabled, timing is increased and AFR is decreased (leaner).

So, if I change what rpm EGR comes in at (say concentrate only on cruise rpm range I desire, say 1800 rpm to 2300 rpm), physically disable the EGR valve, and instead of INCREASING timing, decrease it slightly if needed, or just leave it zero degrees change, should force the AFR leaner (or does the nature of EGR flow make it leaner? I thought EGR was introducing inert gas) and potentially cruising slightly leaner.

Now, this is likely not emissions legal (unless your car doesn't come with EGR factory), but might be worth the evaluation...

Maybe like GM uses the Virtual Fuel Sensor, we can have Virtual Lean Cruise?

Ideas?

The Main function of the EGR valve is to control the creation of Oxides of Nitrogen.(NOX)
The higher the combustion temperatures, the more NOX that is created.
The leaner a vehicle runs the hotter those temperatures.
Hence a rich condition is desired for the goal of limiting NOX.

The EGR achieves this by induceing inert gasses(as you said) and maintaining the same amount of fuel being induced. The inert gas simply displaces some of the oxygen(approx 10-20%). This causes the desired rich/cool condition limiting NOX.

Just wanted to try and help out
truthinker

[N0DIH]

But has inserting EGR into the mix to dillute it you lose performance, that is a given. So we boost timing to recover some of the lost performance. I have also read in GM FSM's that it leans out the fuel mixture some also. There is so much EGR that we can also lean the mixure some to also help some economy. Some people claim better mpg with EGR than without. I do not subscribe to that theory and have 30K miles with it to prove it compared to before without it.

My thoughts are to sabotage the EGR system to actually disable the EGR valve operation, where the PCM thinks it is open, then to allow it to work normally, disabling the errors, and tune the timing to not change during the intended EGR operation (with the LT1 I have a whole timing map for EGR vs rpm vs vacuum) with no EGR flow, instead of boosting the timing, which is typically when pinging would occur.

If anyone has a WBO2 in the car can you please verify that during expected EGR valve operation that the mixture actually DOES lean out?

[truethinker]

You are completely right that the amount of fuel being injected is decreased but as to the exhaust mixture showing a lean condition; it should not. The exhaust mixture should show rich. If you think about it as if you are introducing a 30%dcrease in the amount of oxygen and a 15% decrease in the amount of fuel. Thats still more fuel than air. Though I cannot make this a statement of fact as I ahve never watched the O2 sensor during opperation. I do believe that the exhaust should read rich even with the reduced fuel inlet