madmatt9471

I put on a 78mm Throttle Body (Stock one Bored to 78mm w/New 78mm Blade)

Between the Blade and Bore there was more air space than the stocker, making it idle high!

So on start up it idled "High" and then calmed down a bit to where stock idle belongs.(computer reset the idle where stock should be)

SO! what I did was take the "FLY BY WIRE" motor off the side of the TB and turned the gear on the motor to see if I could close the blade more than where it was at. Which I was not able to do! (Match the stock blade to bore space)

When I put it back on it sputtered and had "reduced engine power" message and ran like crap! My fault I know! Put the stock one back on runs fine, cleared trouble codes too!

Thus throwing the calibration "OFF"

What I need to know is:

What did I do? Does anyone know? and

HOW CAN I RECALIBRATE THE FLY BY WIRE MOTOR? Does anyone know ? I want to fix it! HELP!

Thanks,Matt

mvvette97

I don't think you can mess up the calibration on the motor. I have had mine of alot of times and spun the motor by hand and never had that happen. I did forget to plug in the TPS one time and I got the same message as you.

vettenuts

If I remember correctly, the motor closes the blade on cold start and then opens it a fixed amount (I believe its 8 degrees) for startup. Since you hogged it out, your startup RPM is going high with this setting. The guys in the tuning section may be of help as well.

madmatt9471

Thanks for the responses fella's.

Anymore will also help!

For some reason after I had it appart, to look at the gears to see if the blade could be closed a little more, then put it back together and reinstalled it it just popped and sputtered and had all the messages.

I checked all the connections and TPS TB motor etc and all were connected, so I put the stocker back on and walla NO MORE PROBLEM!

Where did I actually go wrong I wonder? Any more help much appreciated!

What then can actually be the problem?

Does this actually mean a person can take the motor off and spin the gear and have no implications? (It's what I thought am I wrong?)

Thanks,Matt

Bill Curlee

Sounds like your Throttle Position Sensor (TPS) voltage is wrong and causing the PCM to enter reduced power. Put the new TB back on and when the engine is at idle or ignition ON engine off, check the TPS voltage. Im at work and dont have acess to my manuals but there should be a set idle voltage something like (.045 vdc) Need to look up the C5 LS1 TPS idle setting voltage to make sure Im telling yu the correc value.

Once you get the DTC, it going to remain in reduce power mode until you clear it.

BC

DIXZ

I found this in the service manual for an '03:

The throttle body for the TAC system is similar to a conventional throttle body with some exceptions. One exception is the use of a motor to control the throttle position (TP) instead of a mechanical cable. The other exception is the new design TP sensor. The TP sensor mounts on the side of the throttle body opposite the throttle actuator motor. The TP sensor is actually 2 individual TP sensors within 1 housing. Separate low reference and 5-volt reference circuits are used in order to connect the TP sensors and the TAC module. The TP sensor 1 signal voltage increases at the same time that the throttle opens. The voltage increases, from approximately 1 volt at 0 throttle to above 3.5 volts at 100 percent throttle. TP sensor 2 signal voltage decreases at the same time that the throttle is opened. The voltage increases from approximately 3.8 volts at 0 throttle to below 1 volt at 100 percent throttle.

HTH

madmatt9471

Bill and DIXZ,

I do have the '98 Shop manual and DIXZ I read the same thing so I hearing you on that.

From what I gather so far is that it does not matter that I spin the TB motor actuater when it is off the TB. Makes no difference at all.(Really hope I'm right on that)!

So here's what I think, and believe it or not it's 4:06am and I think I found out what I might of done to make it do that.

It is a Stock TB that was bored to 78mm(Really made a diff WOW!) the set screw on the bottom(Stock screw is covered w/a plug) I tried to adjust to bring the throttle blade to a more closed position and it did nothing at all.

Now the computer will bring the throttle down on it's own when it is to high on the initial start up after a few seconds,

What I think I did was leave the set screw, on the bottom of the 78mm TB, run in too much "NOT" allowing the computer to have the TB motor close the blade automaticaly, So what it did was hit a stop thus making it get a false reading on the TPS giving me the sputtering and reduced engine power. (DANG!)

I will test this theory in a week, I sent the TB back to be checked thuroughly.

I think we might have solved this. This will be good info for me and others on the forum in the future so I will definetely "UPDATE" this thread!

Thanks fella's!!!!

Thanks,Matt

DIXZ

Matt, thanks for the update. Keep us posted on your findings.

comecorrect

Where did you get the 78mm blade from? Thanks!
MIKE

madmatt9471

Mike I got the TB from XTREMEFI a vendor on EBAY who I used for my '90 Vette when I got a 52mm TB for my L98. It was perfect and I trusted the man as he has a good product.

This one just has too much space all the way around the blade as if it wont close far enough, it just rests in an open position too much. If it were a little closer to the bore or less space the idle would not jump up at initial start up like on the stocker!

Hope this answers your question with a little more info!

Thanks,Matt

screw991le

Fly by wire? What do you have an F/A 18 Hornet in there. Sorry I had to.

INTHERED

It could be the set screw but most likely the people who ported the TB got a little carried away and there is just too much clearance between the blade and the bore. I have sent several back for this same problem but they were from a different vendor.

INTHERED

madmatt9471

Dude you are so right. as a matter of fact the individual I bought it from got offended saying it was not that he overported it.

It is to big or the blade is open to far. So I sent it back. We'll see.

I'll keep everyone posted as to what comes of it. I told him if he has a good product that there are many other Vette owners I know on the forum that are looking for a quality piece and before I can talk it up the TB needs to meet the right criteria before I can speak well of him and his work and his company!

See if it's just this TB than I'll let everyone know and more than likely
he'll get some more business if not then here goes the stay away from post

Thanks,Matt

madmatt9471

Here is an update!

So far he says there is nothing wrong with the Throttle Body and it is good! even though my stock one on initial start up is at 1200 RPM's then drops down to 600 RPM's and the one he sent me is at 2200+ RPM's on initial start up then takes longer to drop down to 600 RPM's.

I told him to send it back to me and I will not send in my stock TB for the $89 core charge(I'll eat it!).

What I probably will do if I do not want it, is do a "PAY IT FORWARD" for whoever might want it for free (78mm TB) just pay the shipping.

I'll keep you up-dated! I did ask him not to send the same one just to do an exchange since it is his policy!

Thanks,Matt