HAPPY NEW YEAR TO ALL

TUTD 

Dan Hagerty, Vetteworks, Auburn has not given up on trying to make the tap shift work.He's like a bulldog, with an idea. But he's stumped why the tap shift buttons are not being recognized by the transmission control module, TCM. We both know it's something simple, as was the cruise control. Just finding the correct combination of buttons, in this case.

If you are a Corvette owner who likes to occasionally put your car on the track or if your car is 100% race Dan has some great safety products for your car. I would go see him or give him a call. He's very knowledgeable about Corvette and he's a great communicator. 

With all of the reloading of the VIN numbers using the Trailblazer, Yukon and staying away from the Corvette, on the word of Jared at Current Performance, who has caused me two months extra time in getting my cruise control working due to the error in the pinouts, remember. Well, it's happened again. 

In the search for help with the TUTD buttons, I somehow came across a fellow by the name of Mark Romans. I then contacted "Mark Romans Tune" in Sac CA. Mark actually works for GM but has a tune business on the weekends. A great guy to talk with, and very knowledgeable when it come to late model GM stuff, especially the computers. He told me to go ahead and load the Corvette in the TCM. Even though the Corvette has a BCM he said the Corvette TCM signal doesn't go through the BCM. He told me a lot of tuners know there is a BCM in the Corvette and therefore tell everyone to stay away from them, that it won't work. But this is not the case. So, back to Sumner Chev to load a 2013 vin from a Corvette I found on Autotrader.com. Actually, I brought along another vin from an 08 Vette just as a backup, since both were on Auto Trader in the same location.

Here Steve S, at Sumner Chev has just completed loading the TCM with the backup 08 since the 2013 wouldn't load for some reason.  Now it's time to go out and test drive. As I pulled out of their parking lot I first noticed that the car was shifting. This is a good thing that sounds rather simple, but in reality, if the loading is done wrong  the car goes into limp mode, remember back almost a year ago, when it was 2nd gear only.

Well, this time it was shifting into all of the gears so I thought that just for the heck of it, on the way back to the dealership, I'd try D-5 which is one position down from drive. This is the position that the gearshift lever needs to be in for the TUTD shifting. All is good, the car is still going forward. So, the next step would be to actually test the TUTD buttons. Now, after all of the headaches, what are the chances this will work, virtually right out of the box? WOW with a capital "W". It started to shift up and down every time I touched one of the corresponding Tap buttons. LIFE IS GOOD. Actually, there's nothing to it. Just touch one of those buttons and it shifts. Can't figure out what took so long.

The next step was to bring the 33 out to Eric's Automotive, Enumclaw Wa. to have the engine and transmission tuned and to see the output of the engine power. Right now you might be asking yourself, why not have GM do the tuning. With the newer cars the dealerships are very limited in what they can do with their regulations and equipment. Take for example the automatic door locks. A friend just bought a new GM car and wanted the automatic door locks turned off. He was told they can do this on police cars but not for passenger cars. So there are some things that only the dealerships can and can't do. The same applies to the aftermarket guys. I thought I'd asked while at the dealership about tuning my transmission. They can load the factory specs only. Not what I want.

With the HP Tune software found at www.hptuners.com they have opened all of the adjustments to the engine and transmission. I bought the software but without having some experience with what it offers I decided to get some OJT from someone who lives and breaths this software. I do know that if doing the transmission wrong it can try to shift into two different gears at the same time, which will basically turn your transmission into a brick. In the above picture you can see, int the upper left, it's showing D-2 can be loaded with "pattern A or pattern B" under different circumstances. Also note that this page is for the "auto shift speed" section.

There are tables for speed and different tables for firmness or pressure. We left the auto shift tables stock for the time being but the tables for TUTD have been changed. 

Essentially, the new transmissions have electric servo valves that do the shifting for you. The first four gears are actually the same as manual gears as in a manual transmission, only the electronics and servo-valves of the transmission are doing the actual shifting. This is just like what a person does with a manual transmission, only the new automatics can now be set up to shift much faster than a person can move his arm. By reprogram the speeds and pressures. With the TUTD style of transmissions you can have a combination of both. Easy shifting during normal starts and cruise and rapid shifts during hard acceleration and TUTD functions.

Since we have all the functions of the running gear complete, it's time to get this thing up and running the way it's supposed to run. First we need to anchor the car down on the dyno and hook up my laptop to make the adjustments. We also hooked up wiring from the dyno to the exhaust, sparkplug etc.

In this picture you can see the rollers of the dyno under the rear tires and my laptop.

Here's a picture of the dyno screen.

Shortly after we started the car, Eric noticed that he wasn't receiving any signal from the mass air flow (MAF) sensor. We did a cursory wiring continuity check, changed the MAF with a new MAF sensor, still no signal.  He said it's pointless to try and tune for performance until the MAF is functioning properly. I know a lot of hotrods run without a MAF and asked how this is possible. Eric showed me a number of tables similar to the one above. The computers in your car have the ability to run on a programmed set of these tables. These tables are called VE tables.

VE-Volumetric Efficiency

VE is map of predicted engine performance based on speed and MAP.

VE is how much cylinder

filling occurs based on engine displacement. This value can be over 100%

These are set for average, including the ambient temp, engine temp, humidity, altitude, pressure, speed, timing, airflow through the air intake. So essentially your car will run in a limp mode to get you home or to the repair shop. And, that's what I've been running on. Of interest, something I recently found is that a number of people have commented on huge drops in their fuel economy when their car had been getting good economy. In a lot of cases their MAF's have gone bad for one reason or another. The use of K&N air filters is high on the list. These air filters can be cleaned by washing, then are to be sprayed with a light oil to aid in the air filtering. If too much oil is used, the oil will mist out of the filter media and some collects down stream in the MAF which destroys the MAF. Ergo, the computer goes to limp mode and your fuel economy goes in the tank.

Now, to run at peak performance all of the above mentioned factors need to be measured thousands of times per minute. This is the job of the mass air flow sensor, in addition to a few other sensors, like the O2, throttle position, cam, and  knock sensors. 


After looking into the wiring of the cruise control, the five wires to the MAF shouldn't be all that difficult to figure out. I remember changing the connector to the MAF about two years ago. There are two different styles of MAF's one called a credit card style and the other not a credit card style, or simply a round style. Both are five wires, but take a slightly different connector. The credit card style is used for the Corvettes and the round one is for the Trailblazers.  While initially contacting Current Performance for my harness I told them I was going to be using the credit card style since it requires less room to install. But since I was using the Trailblazer program for the ECU they installed the connector for the round or Trailblazer MAF. Not what I asked for. I contacted them, and they sent me the credit card style connector and didn't mention that the wiring was different for the two, even though both have five wires and look basically the same. I changed the connectors and used the same wire configuration. Wrong. So after searching the internet I found the configuration for the credit card style, changed the wires, hooked up my laptop and found the section on the MAF now working.

I need to take some of the blame for the MAF problem but the total lack of concern and lack of response from Current Performance,"after the sale " really stands out when dealing with great communicators and businessmen like Dan and Eric.

Anyway, back to Enumclaw to see Eric and his dyno machine.

The first run was to see how things are set, right out of the gate. We stopped the run at about 4700 rpm. No need to go further as, the black line, Air/fuel mixture is way off.

After Eric finished tweaking the air/fuel and a few other things this is the results. 428 hp and 417 lb.ft. This is at the rear wheels, therefore the engine hp is about 522 and the torque is about 656 lb.ft.

The run was terminated at 6600 rpm as the rev limiter was just starting to kick in. What is really important is the torque curve, peaking at about 4800 rpm. Not too sure what this means but I'll keep it in mind ha.

The final step was to use HP Tune to adjust the line pressures within the transmission. Eric set these so that the shift is much firmer when going to the TUTD buttons. There is more that can be done with this but at this time it's a good starting point.


A little time off to watch the Superbowl........have a great day

that's it for now...............................