Tuning 8L90E with blue cat

[Jims72nova]

I have a GM connect and cruise LT4 with the 8L90E package in my '72 Nova. The default tune for the trans is horrible, in fact it's so bad I can't even drive it. I have had an online tuner attempt to tune it with no luck. Now, I want to try and fix this myself. I have found that others have used the blue cat application and I would like to use it as well but there is not an option to export for the 8L90E and not a lot of info that I've found on using blue cat with this trans. So, has anyone here used blue cat and if so, can you give me some guidance on how to make this work? There is not an option in blue cat to select the 2017 Corvette (this is the vehicle the vin from the ecm shows) for the shift slope.

vehicles.png

I have also attached the latest tune.

Thanks
Jim

[MakesBadDecisions]

Have you verified the ECM/TCM are outputting the correct speed? Does your car really have a 2.41 rear gear and 26.05 tall tire?

Bluecat works great as a starting point. I have found that they still take lots of hand blending of the shift schedule and driver demand table

[Jims72nova]

I have 3.50 gears and a 27? tire. I know nothing about HP tuners or tuning but purchased it when I got the engine and trans installed.

[MakesBadDecisions]

You will need to make changes to the tune file to correct the speed within the ECM/TCM. Using the gear/tire wizard in the software will be your starting point. Once your scanner speed is within a 1mph of GPS actual you can then work on shift schedule and personal preference of that schedule. Be mindful that torque based systems like this can be a delicate balancing act of driver demand tables and shift schedule and that small changes in each one will make big changes to how the vehicle feels.

[Jims72nova]

Actually I posted the wrong tune file. In the newest tune file (attached) the tire size and gear ratio is correct. Also, the ECM/TCM speed is within 1 mph as I used my GPS and also tested it with my wife driving behind me. My biggest concern about this whole process is which vehicle do I select in the blue cat on the dropdown as each one has different settings. And, in hp tuners, I open trans, then shift scheduling and there is normal, pattern A, pattern B etc...I have no idea what to put where...LOL. Going to search youtube and see what I can find.

Jim

[MakesBadDecisions]

The drop down for throttle type sets the shape and spread of the shifts. You can right click on the table and open a 2d graph, open the up shift and down shifts, then change the throttle types and watch the change. I start with the Camaro settings as a base to start from. You can log the channel that says which pattern you are in, when in doubt change them all in tune file to the same until you can differentiate them, doubtful in a swap you will have the ability to switch patterns. You will have to manually copy and paste, right click and copy from blue cat then right click and paste into the tune file as the export window does not work for GEN5, at least the version of blue cat i have.

Big thing to remember here is that cramming 8 gears into a schedule that "feels" good is tough to do and takes lots of hand blending and testing to find the happy medium.

[mbray01]

Using the bluecat tool, this is where I would start and see how it feels

use the 90-105tb as the base
then correct gear and tire ratios
tc gear min to 6
accel to 6
wot to 6
on shift settings use factor 1.05, offset -7, up 8, down 8
this will give an extended shift feel, you can turn them by adjusting those settings, but this will keep it from feeling like its always lugging

[TheMechanic]

I have 3.50 gears and a 27? tire. I know nothing about HP tuners or tuning but purchased it when I got the engine and trans installed.

Yikes. You are kinda jumping into the deep end with this. Sure you don't want to get a seasoned tuner involved?
When you say it is un-driveable, what do you mean?
To soft?
To harsh?
To late?
To early?
As MakesBadDecisions mentioned the starting point is basic inputs like gear and tire. The (3.50) 3.42 gear ratio will make it shift to early.

[Jims72nova]

Yikes. You are kinda jumping into the deep end with this. Sure you don't want to get a seasoned tuner involved?
When you say it is un-driveable, what do you mean?
To soft?
To harsh?
To late?
To early?
As MakesBadDecisions mentioned the starting point is basic inputs like gear and tire. The (3.50) 3.42 gear ratio will make it shift to early.

Meaning, drive-ability is horrible. It shifts super fast from 1-2, then sometimes hangs from 2-3 and if I get on the throttle, it downshifts to what feels like 1st or 2nd gear and I feel like I am going to blow the motor. So I've never really gotten on the throttle hard on this to see what it will do as I don't want to hurt it. Also, when I come rolling to a stop, it stays in 2nd gear and then at maybe 1 mph shifts to 1st and that makes the car jump hard.

As for finding a tuner who can do this. I've already brought the car to 2 places and even tried an online tuner with no luck. In the back of my mind I am starting to think this will never be right. I've considered bringing the car to the Chevy Dealership as well. Just not sure they can even help.

[MakesBadDecisions]

The dealership will more than likely not touch it, ours wont touch anything that isn't stock and they then send them all to me.

Question and not to sound rude or mean. Have you driven a LT4 car or anything new enough that has an 8spd auto in it for any significant amount of time? These 6, 8 and 10 speed torque based vehicles are a much different driving experience than most are used to, especially in the swap world. The biggest complaints I get are, it shifts too soon, it is always shifting, on the highway it shifts down to far, the trans doesn't shift when i want, it down shifts too soon or not soon enough. Those are the big ones and the problem starts when we try to compare to the 4spd autos or 6spd manuals. We have several swaps running the 8 and 10 speeds, everything from classic muscle cars all the way to full tilt rock crawlers. Each of those builds took a serious amount of time to get the shift schedule, convertor schedule and driver demand tables to act more to what we are accustomed to. I would venture to assume that a light vehicle like yours is going to be very sensitive to engine and trans behavior.

[MakesBadDecisions]

Here is a schedule to try based on the last file you put in the forum.

Get a log of this driving and attached to your reply on how this feels.

[Jims72nova]

Yes, in fact I used to have a 2017 Corvette with this exact engine and trans setup before I bought my wife a new 2021 vette last year. I understand what your saying about the way a car drives and I can tell you that it's no where near normal to drive this car. The strange part about all this is at 70 mph, this thing cruises along nicely, that is until i get on it then it gets all freaked out on me. If you take a look at my last data log (I just attached) my IAT goes red and it doesnt really show me going over like 30pmh which I did. I believe I have the wrong things set in the channels for the data log. For example not logging from the ECU but the sensor (if I am correct). I think what I need to do is reset my data log and start fresh.

And I would never think your being rude as I appreciate your input on this matter.

Jim

[MakesBadDecisions]

Ok good, just want to make sure we are comparing apples to apples. I had a customer once that was comparing an old ass F1 to his Ferrari and wanted me to make the F1 drive like the Ferrari, not possible.

Use this channels list as it contains more info needed to get a good picture of what is going on. That is very strange on the MPH readings as it shows random spikes in data. Lets see if this channels list produces a better result.



Edit - How is your MAF mounted? It seems like it has a lot of reverb at times. On all gen5 swaps I always put a piece of 1/4in dia honeycomb air flow straightener right before the MAF. I have found this help smooth out measured MAF when its mounted in not an ideal location.

https://www.amazon.com/Aluminum-Hone...0WISSLAS&psc=1

[Jims72nova]

Ok good, just want to make sure we are comparing apples to apples. I had a customer once that was comparing an old ass F1 to his Ferrari and wanted me to make the F1 drive like the Ferrari, not possible.

Use this channels list as it contains more info needed to get a good picture of what is going on. That is very strange on the MPH readings as it shows random spikes in data. Lets see if this channels list produces a better result.



Edit - How is your MAF mounted? It seems like it has a lot of reverb at times. On all gen5 swaps I always put a piece of 1/4in dia honeycomb air flow straightener right before the MAF. I have found this help smooth out measured MAF when its mounted in not an ideal location.

https://www.amazon.com/Aluminum-Hone...0WISSLAS&psc=1

I really appreciate you taking the time and doing this for me. I am going to try to get out tomorrow with the new trans tune and data log but my wife and I have an early flight Friday morning for Miami to hop on a cruise so that damn honey do list will be extensive I am sure, lol. If not tomorrow, then the 19th (fathers day) when I get back I will get out there and then post the results here.

Again, you did not have to do this but it's much appreciated. A big Thank you!!!!

As for the location of the MAF, you can see it here in this pic.
maf.jpg


Jim

[MakesBadDecisions]

You lucky dog, have fun. My wife is itching to leave town and SW Montana is just getting nice enough to get the toys out, she will have to wait just a bit longer. Do what you can when you can and no worries on my end.

The MAF position on the inside of the bend before the throttle body is a little concerning, as that air will increase speed on the inside of the bend before the TB and may be causing the noise i am seeing. I think the addition of the honeycomb in the joint just ahead of the MAF towards the filter will help with smoothing out the MAF. Just a recommendation.

[Jims72nova]

You lucky dog, have fun. My wife is itching to leave town and SW Montana is just getting nice enough to get the toys out, she will have to wait just a bit longer. Do what you can when you can and no worries on my end.

The MAF position on the inside of the bend before the throttle body is a little concerning, as that air will increase speed on the inside of the bend before the TB and may be causing the noise i am seeing. I think the addition of the honeycomb in the joint just ahead of the MAF towards the filter will help with smoothing out the MAF. Just a recommendation.

I will get it ordered tonight. Can I ask how you secure the honeycomb in place? And I assume you can cut this with a pair of metal shears or a Dremel?

[MakesBadDecisions]

If the boys are building the intake I will have them bead roll and lip to the inside just inside the edge, approx the width of the material, then they bead roll to the outside just a little further in from the edge, this is to give the boot something to grab onto. Once the bead rolls are in then they drill several holes around the outside edge halfway between the end of the tube and bead roll, this is to allow the 2 part panel bonder to ooze out giving a little more of a mechanical lock. That is of course the best case scenario and not always possible. Many times we have drilled the holes on the outside without the bead rolled inner and have had no issues. Just use the best 2 part panel bonder you can get, most autobody supply places will have it.
I use a pair of fly tying scissors, very small, sharp and strong. The stuff cuts easily. I use a paint marker and trace around the tube that the piece is going into. Then I cut the spans out on the paint mark and once cut out the I lay it flat on a metal table and push the tube onto the mesh while turning in one direction. I ruined plenty of material till I got the hang of it. I wear TIG gloves when working with the stuff. Once the piece fits you can push it out from the other side, use care and as much surface area as possible to push on. Once I am happy with how it fits I will apply the panel bonder to both pieces on the mating surfaces and slide them together and clean up as much of the stuff as you can before it gets hard, its a real PITA later on.

I dont think you need to put a rush on this right now by any means, it was just something picked up when I was gleaming through that log. Once I see a log using the channels I sent along with that shift schedule change and with your feedback I can make a better decision on what you might be feeling in the vehicle. The 30mph thing has me questioning a couple things, but until we get a log I am just not sure.

[Jims72nova]

I do not have a bead roller but I will see what I can do. I tried to import the xml file you sent as a layout in the editor but it failed. Any easy way to get all these channels without having to manually add them one by one?

[MakesBadDecisions]

Option 1
Save that channels list to your User/Documents/HP Tuners/Channel Configs folder.
Then open the VCM scanner and then load channels list, it will open an folder window. Then select the channels list you saved earlier.
After you get that open, make sure to start vehicle, connect the scanner and the repoll for supported parameters, that is found under the vehicle dropdown tab.

Option 2
Open the log attached, then save the channels list, then connect to vehicle, repoll and watch the data populate.

[MakesBadDecisions]

Also,
Wanted to warn you, that shift schedule does have some fairly aggressive zero pedal downshifts when coming down from highway speeds to lower speeds. The 6-5, 5-4, 4-3 shifts will happen around 1500ish RPM. Just wanted to mention that before you experience it and get nervous.