EFI updates.....

[mrvette]

I wonder if any particular improvements to a batch fire L98 system with LT1 induction on my 355 roller engine would lead to any fuel economy improvements...

the cam is a basic L98 and idle is great, runs like really good from a 600 rpm idle, chip seems happy in the speed density program....

so the question is....'does any change in the computer, like to sequential and maybe a second O2 sensor make any worthwhile changes to the overall operation?? and what would those proposed changes make to fuel economy??

:skeptic:

 

[Fuelie74]

It would be an improvement, but as to how much its hard to say. The bigger question is are you really prepared to go to an aftermarket PCM or a GM 411 running a custom OS?

 

[mrvette]

It would be an improvement, but as to how much its hard to say. The bigger question is are you really prepared to go to an aftermarket PCM or a GM 411 running a custom OS?

Keep it cheep....but I suspect somehow that 30 mpg on the new vettes is mostly in the computer than the rest of the car....

 

[Fuelie74]

A good part of the mileage is coming from the head design and low end power of the LS engines and the gearing. Some of it is the efi system though. Cheapest route would be MS, followed by using GM hardware and a tuning software like EFI Live or HP Tuners, then would be the aftermarket plug and play stuff. Bottom line if you really want to update that badly get a grand out.

 

[mrvette]

A good part of the mileage is coming from the head design and low end power of the LS engines and the gearing. Some of it is the efi system though. Cheapest route would be MS, followed by using GM hardware and a tuning software like EFI Live or HP Tuners, then would be the aftermarket plug and play stuff. Bottom line if you really want to update that badly get a grand out.

My engine is a 355 roller engine with now an L98 cam and LT1 induction and 113 aluminum heads, headers, duals with H pipe....nothing to write home about....

so rewiring for a junkyard GM computer from a LS engine don't bother me, just if the sending units are slightly compatible.....then to the programming, via a WHAT??

 

[Fuelie74]

My engine is a 355 roller engine with now an L98 cam and LT1 induction and 113 aluminum heads, headers, duals with H pipe....nothing to write home about....

so rewiring for a junkyard GM computer from a LS engine don't bother me, just if the sending units are slightly compatible.....then to the programming, via a WHAT??

What you want is a 411 PCM GM used that computer in like everything between like 2000 and 2002 so they are all over for cheap. You shouldn't have to pay more than $40 for that PCM from a junkyard.

The thing with that PCM is it was used to control the LS based engines in C/K trucks, vans and in Camaros, but it was also used to in some G vans that had a Vortec 5.7.

Once you have the 411 PCM it will need to be flashed to the VIN of a G van with a 5.7. It doesn't matter what the PCM it came out of as long as it has the right part number. The best way to find a VIN to to search ebay or craigslist for that vehicle and filter the search for sale by dealer, because dealers will normally post the VIN. Now to get it flashed you need to have access to a GM terminal with a tech to and the adapter to program off vehicle, so not every shop can do this for you. I do happen to know a member of this forum that has access to that at work and would be happy to flash it for you as long as you pay shipping both ways.

Now that you have the PCM programed. You will need to pull up a wire diagram and connector end views for the vehicle that you borrowed the VIN from and pin your new engine harness to match.

Once that is done you will need to install a vortec timing chain cover and crank sensor, MAF, and distributor (not sure if the one you have would work).

Now that all of that is done you will need a tuning software like HP tuners or EFI live to disable that VATS out to the PCM. There are some places that do mail order tunes and VATS removal, but I am not sure if they will be able to get it close enough for your needs.

Hope this all makes sense. All together your really only talking a couple hundred dollars in hardware if you shop it right, but HP tuners to make it all work is $650.

Then once you get it running if you really want to get funky you can make that set up run speed density or even COP, but I would guess that is farther than you want to go.

 

[Fuelie74]

Also I know you are a 200r4 guy, but this would allow control of a 4L60E or a 4L80E trans that would make many guys happy.

 

[mrvette]

Thanks Fulie, but it's more T&E than it's worth....especially doing all that computer tuning....can't see a ROI on it....oh well....

but what is COP?? I know speed density that's what I'm on now, and MAF is obvious....never heard of the other....

:thumbs:

 

[Fuelie74]

COP = Coil on plug

 

[Fuelie74]

Thanks Fulie, but it's more T&E than it's worth....especially doing all that computer tuning....can't see a ROI on it....oh well....
:thumbs:

I really don't understand what you want. You say you want to upgrade and use junkyard ready parts. This is about as cheap and easy as you can get for that. Also you are never going to get the maximum fuel mileage without doing some tuning yourself or taking the complete car to a tuner shop.

You say its no trouble building the hardest and that is the hardest part of the whole project.

The tuning part isn't going to be that be either. As long as the PCM has the correct operating software to start with and that is what programing to a van VIN would provide. At that point you could have the VATS removed mail order for $100 and it would run a Vortec 350 perfectly. Now being a MAF setup you may be ok with your setup that way. If not you could always let someone else tune it for you if you don't want to mess with it.

1. Buy PCM = $40
2. Have PCM programed to van VIN = cost of shipping
3. Build wire harness = junkyard
4. Change timing chain cover to one off Vortec = junkyard
5. Change distributor??? = junkyard
6. Install MAF = junkyard
7. Have VATS removed from PCM = $100

 

[mrvette]

Fuelie, honestly, I dunno what I want from the mythical change, better fuel economy, yes, but other than that, I dunno what to expect, IF I do this switch the present system will probably wind up in the motor home....with a stock TPI instead of the LT1 setup on the vette now....

changing to the Vortec timing chain cover, and cam/crank sensors means I have to get the sensors with the cover...fine, I hope....trick is to find a y2k van in the JYard that still has the shit on it....junk pickers here in Jax are pretty through and so I suspect not so easy....

I going to keep this thread in mind, and need put off any decisions till maybe spring/summer, spend winter doing other shit problem solving....like taxes, etc.....

:crutches::rain:

I DO say thanks for your help here, I have some concept as to what is going on with all this now, I did try a aftermarket computer some time ago, and even though it was supposed to be ok, I had nothing but issues with the programming, and am gun shy on that shit ever since.....

:sweat: