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

[N0DIH]

So if the valve was disabled, but the operation remained as intended, what would the result be? That is the question. Would it give you a leaner cruise operation during that time only?

[truethinker]

If we are correct in our assumption that the amount of fuel being injected is decreased during EGR opperation, then yes; it would cause a lean condition. But it would use the same exact amount of fuel that way as it would during normal EGR opperation. There are two possible problems though: 1. I have hear reports of removing the EGR causing pinging due to the fact the the mixture gets so lean with the inert atmosphere taking up space. 2. im not sure how you would get it to work because the is an EGR pintle position sensor that runs in parallel to the activator circuit. It checks to make sure that the EGR is indeed where the computer comanded it to be. It will know that the item isnt there and isnt moving.

[joecar]

truethinker, welcome to the forum. :cheers:

[truethinker]

yea i guess i forewent the whole introductions part but im knew to this forum as im sure is obvious. Im gonna be buying efilive within the next month and wanted to get a feel for what info was availible to me.

here's an intro

I Have a '96 chevy k1500 5.7L that will soon a cam, new ported and polished heads, roller 1.6 rockers, a 12200411 computer, headers, dual exhaust, full tranny overhaul and full rear end rebuild. along with a braked dyno tune and eventually a street four link.

all work done by yours truely

any input over the next two months would be greatly appreciated

peace
Jesse

[N0DIH]

I have a 99 K2500 454 Burb that I am looking at doing a 0411 swap so I can ditch the old school PCM.

[ScarabEpic22]

OK, I feel really stupid, but what is so great about the 0411 PCM? Is it an LSx based one so you can run a COS on it?

[truethinker]

OK, I feel really stupid, but what is so great about the 0411 PCM? Is it an LSx based one so you can run a COS on it?



I have not yet experienced the difference personally yet but I have read many accounts of improved opperation. I have a '96 truck so for me the 411 is will be 5 years newer technology for one thing. It has faster processing and is much more compatible with tuning. There were many glitches in the '96/'97 computers which has alot to do with my wanting to switch. also the 411 is compatible with EFIive. The loophole that allows use of this LSx computer with an L31 engine(the 96-99 V8) is that the 411 was used in the exrpess vans with an L31. that makes it the newest computer that is useable.

There are reports of better fuel mileage, smoother shifting, better idle, more power and all around improved drivability


I'll give you my personal opinion based on experience in a month or so

[ScarabEpic22]

OK, thanks for the quick rundown man. Makes a ton of sense to me, I might have to do a 07+ LL8 swap for my 02 PCM as for 07 the P12 PCM gets another mb of RAM, think 2MB. Im thinking that may be much more accommodating for a COS for the LL8.

[hquick]

The 0411 allows the use of COS, which makes for tuning to suit FI alot better.
I'm in the tuning process at present. EASY, easy swap!
I had to run 4 wires to the trany and that's all.
The 96-98 PCM's are also limited to I think 5600rpm.

[N0DIH]

My 96 after Jesse tuned it would go to 5900 (I did it once), but I honestly didn't push it, didn't want to lunch the 235K mile engine! Unless the tach was off, that is how high it ran to. I honestly don't remember if the rev limiter kicked in or not, we lost the truck to an accident with a hit and run with a semi on the interstate in May 06. I sold it to someone in Aurora, IL, so it is still around, but Jesse has the PCM now.

What four wires did you need to run to the trans? I have a 4L80E with a L29 454.

[truethinker]

My 96 after Jesse tuned it would go to 5900 (I did it once), but I honestly didn't push it, didn't want to lunch the 235K mile engine!


Thats great. And people say domestic engines dont last. pft

My 96 k1500 has 229,000 on it right now and is still driven every day. And it's about to get a major wake up call lol

[N0DIH]

And mine didn't leak a drop, didn't burn a drop and ran like a champ. I had it from 178K to 235K and did nothing to the engine short a starter at 230K, an idler pulley/belt and a battery/alternator when we got it.

I can't knock the 350 Chevy for reliability for nothing.

Just ask any limo company how long the LT1 Fleetwood limo's last. I have a LT1 Fleetwood (not limo) and at 218K is runs fantastic, and will still smoke a stock Hemi Ram pickup from 40-100 mph.....

[truethinker]

Yea. same here. I got it at 212k and know for a fact that nothing was ever done to it aside from regular oil changes.

And it is actualy handleing some bolt ons without any issues.(aside from the fact that the computer doesnt appreciate them.) [411 SOON!]

I just ported and polished a set of heads and installed them and full roller 1.6 rocker arms and headers, MSD 6A and coil.



One note to you high mileage L31 guys - - - when I had my Dist. out I noticed the the gear was worn badly. This is expected but the problem is that it is uneven. The teeth start out at around an 1/8" thickness and some were still at that measurement but two were so sharp that I actualy cut myself(literaly) and they were worn to verying degrees in between. I was going to just replace the dist. gear but was told by a tech to not do this under any circumstances because it would cause the gears to lock up on each other.


The point is. If your L31 ever just shut off and wont start - first thing - see if that rotor is spinning. As with mine it's just getting a new cam and gear

just a heads up
peace
Jesse

[N0DIH]

I can see that from the cam walking around, my Olds 350 did it to me and left me stranded... But Olds V8's don't have cam retention plate and once the cam is worn down (flat tappet) the cam is all over the place.

[drdarthinvader]

egr (exhaust gas recirculation) valve removes excessive crankcase blow bye pressure using engine vacuum ,if you remove its effectiveness you will notice a lot more oil leaks lol

[TAQuickness]

Welcome to the forum drdarthinvader!

EGR actually injects exhaust gas back into the intake stream for emmisions purposes. Later years 01+ acomplish this by a change in cam design, hence the lack of EGR equipment.

I think what you're thinking of is the PCV system, Positive Crankcase Ventilation, which releaves positive pressure in the crankcase.

[drdarthinvader]

my bad,got too trigger happy

[hquick]

my bad,got too trigger happy

Lol! That happens. :hihi:

[TAQuickness]

happens to all of us! :cheers:

[jpliss]

I just was checking around and saw this thread i subscribed to.

98 chevy cavlier 2.4, 224,000 miles only replaced the water pump and alt.

96 chevy cavlier 2.4 168,000 miles so far so good

1995 buick roadmaster LT1 178,000 runs like a champ even after sitting for 9 months, replaced the water pump

1999 Buick regal GS blower 3800, 188,000 miles with the boost turned up will run 14.2. I replaced brakes, belts hoses and valve cover gaskets.

1985 chevy suburban 3/4 ton 454, 400 trans 4.10 gears 142,000 miles. tranny needs a rebuild old tow vehicle

2002 Ford F350 dually crew cab diesel 101,000 miles just getting broken in. New tow vehicle

1986 Buick Grand National. 108,000 miles stock unopened engine, boltons 11.68 - 11.72 in the heat of the day.

Some how they just seem to keep going.

The only cars in my inventory with under 100,000 is our mustang gt and my Grand National.


And they keep telling me american cars do not last as long. HUMPH! I turn my nose up on those nay sayers.

I will keep buying the blower cars for 500 - 1500 dollars for daily driver, nobody wants them but they seem to keep going. I let the foreign owners be happy in their over priced used cars with overpriced parts and repair bills.

Just my O2.

[N0DIH]

Yup! I hear ya there, tell that to the suckers who buy the overpriced imports... many are stuck in their own world....


....And they keep telling me american cars do not last as long. HUMPH! I turn my nose up on those nay sayers.

I will keep buying the blower cars for 500 - 1500 dollars for daily driver, nobody wants them but they seem to keep going. I let the foreign owners be happy in their over priced used cars with overpriced parts and repair bills.

Just my O2.