LS2 not getting full throttle

[kochevy67]

Can anybody tell me what would cause the throttle to only operate at 33 percent when it is running. The throttle shows 88 percent when the key is on and not running. I installed this LS2 with a 4L65E in my Chevelle and it is driving me nuts. I had the stock tune put into it and deleted the vats, rear 02 sensors, and the emissions stuff. Also the TCM is not readable only the ecm when hooked up to a scanner. I took the car back to teh place that installed the tune and they can't figure it out either. Any help would be appreciated.

[derekf]

When you say "33 percent" and "88 percent", is that what the ECM is reading or something else?

Is it cable-operated or drive-by-wire? If cable, does the throttle blade open all the way up when the gas pedal is all the way down? (I guess the same question would apply to DBW as well).

Have you taken a voltmeter to the TPS?

[1badchevelle]

are you sure its a ls2 tb? LS3/7 tb have problems with the ls2 system.

[kochevy67]

The ECM is reading the percentage. And yes it is a LS throttle body. Also it is DBW. I have not takena voltmeter to the TPS yet but that will be a good start. I also forgot to mention that I cannot get a signal from the trans controller. By the way the ECM has no codes in it so that is why I am lost on this one.

[Bow Tie 67]

Is the blade on the throttle body gold? If so you need a silver colored one. That is what goes along with the LS2, the other is for an LS3. The LS3 pcm has the TCM built into the pcm.

[kochevy67]

The LS2 is a complete take out and NOTHING has been changed from the previous car it was in.

[Bow Tie 67]

So is the throttle only going to 33% when running? Can you drive the car? Do you have the BCM in the car also?

[kochevy67]

Yes to the first two ?'s and no The BCM is not in I transplanted this into a 67 Chevelle. I have the ECM and the TCM in the car.

[Bow Tie 67]

Is the gas pedal from the donor car? I'm not 100% sure but the BCM maybe needed also.

[tooblue]

Did you try looking at the ETC instead of the TPS %.. ETC should reflect the correct percentages.. How is the car running ?

[kochevy67]

The gas pedal is from the donor car and the not having the BCM may be the problem. The car runs fine it just does not have full power. I need to find a program that can delete the BCM from the ECM. I was told the BCM is like the main router for the ECM and the TCM. I think that may be my problem. If anybody knows a place that is able to do that could you let me know.

[Bow Tie 67]

In most cases that I know the BCM is a seperate box.

[Mike Norris]

I have a few questions and then some info.

What car and what year is everything out of?

What harness are you using? (Custom, Modified Stock?)

Is there any chance you heard the transplant engine and trans were in a wreck? Possible unseen damage.

You say there are no codes, but perhaps whomever did the program turned off some codes that should be on for diagnostics. Just a thought there.

Now for some info. When setup properly and the VATS is turned off, the engine should run properly with no BCM.

If you are using HP Tuners, max throttle position read is 88% with a DBW. I am guessing you are only getting up to 33% throttle max? Or is that your idle percentage?

It should be able to run without an intake tube or MAF sensor on there to check this. If you go from key on and have 88% and check the TB blade, then start it and check the TB blade, does it move?

If you turn the key on and not running and slowly run the accel pedal from idle to WOT, does the TB blade sweep?

What percentage does she idle at?

With the key on and the reading at 88%, what position is the TB blade in?

All 2005 and up LS2, LS3, LS7, L76 and L99 car TB's are interchangeable. Even the newer 2009 and 2010 units thta have a larger body but look similar can be exchanged.

Initally I want to say that some pins in the TB connector or ECM is in the wrong place if someone either built it from scratch or modified a stock harness to match up different parts.

If it comes to it, I am in Indy and can go through it for you and dyno tune it if need be.

Looking forward to the answers to above and see what we can find out.

Mike Norris

[kochevy67]

I spoke with John at Speartech and he gave me something that I will try first. I will let you guys know how it goes. I have my fingers crossed and appreciate all the help everyone has given me.

[73z-6sp]

njmk,l