Finally got to fire my lq9 swap for the first time today. Fired on the first crank but I have a problem with the throttle body. I am using the pedal tac and Ecm from the 2002 escalade I pulled the engine from. Upon starting it started revving immediately so I shut it down. Looking at the throttle body it is locked open. Turning the key makes it blip a little further momentarily but it then stays almost wide open. It feels like it is manually locked in place but I can't see anything that would be holding it because it cannot be pushed shut by hand. Any thoughts will be greatly appreciated.

 

If it is anything like my 09' L92 you should be able move the butterfly manually. Sounds like your TB is messed up or perhaps installed wrong? You can disassemble them to inspect the drive gears inside.

 

Just pulled it apart and somehow it was jammed up in the gears. That solved, the car now idles. Now to find out why I have no throttle pedal. That will have to wait for tomorrow.

 

After much grief with mine I discovered that, although the pedal and tac came from the same vehicle the TUNE was '05 and required a different pedal/tac.

 

Good call. I had texas speed do a base tune to get me running so maybe a call to them is in order

 

Does your throttle body have a long external motor sticking off to the passenger side? Is your TAC module all plastic? If so you have the early DBW that is not used much. It uses a blue and red style PCM connecters and not the newer blue and green PCM. It needs the right OS which I have. I just did a write up on converting it for a 06 90mm gto throttle body.
https://ls1tech.com/forums/conversio...2-dbw-how.html

 

Yes, that's the throttle body that I have. I was made aware of the fact that it was a one or two year only thing when I bought my harness from PSI. It has 2 plugs, with the large motor on the passenger side and the TPS on the drivers side. I'll have to do some reading on your link.

 

Sounds like you may just have a bad throttle body.

 

I know the throttle body "works" because keying the ignition to the run position causes it to cycle itself open/closed, which it does fine. I just have no input from pedal to TB.

 

If you have everything out of the same truck you should be good to go. Who flashed the PCM? There's a chance it got a different year OS flashed into it.

When you bought your harness, did you also buy the jumper harness from the TAC to the pedal from the same place?

 

I purchased my harness from PSI Conversions, and I did get the TAC harness from them also. I did have to cut/weld the pedal to fit my application and didn't take it apart to do so, I guess there is a very slight possibility that in the welding process the electronics connected got hot? It's highly doubtful, but a possibility.

My tune was done as a mail order from Texas Speed, I'll be in touch with them today to see if they have any way to recall what they used. If they can't tell me I'll just send it back off to them for another shot at it. They have 1 year of free retunes included.

 

Ive cut and welded pedals many tomes, and its possible to melt the plastic parts, but im sure if you paid any kind of attention to it while welding, you would stop before itwent that far.

Texas Speed should be able to look up yourtune and give you the year of the OS in it. Hopefully its just a 2003-up tune and a reflash with a 2002 will fix it.

 

I've also got the 02 escalade DBW.
If you damage the APPS, the motor will start and idle, but that's all.
You might try a new pedal sensor. I think it required a safety torx bit to remove.

 

He fixed the issue by swapping the tac motor wires.

 

Thanks to the helpful members of this forum I was able to resolve the issue very quickly. Turns out the 2 throttle body control wires were backwards on the harness I purchased. Pulled the pins and swapped them and all is well again.

 

I dont have anything to add to this thread, But I will take a few minutes of my time and thank the original poster with what they found wrong. It bothers the hell out of me to find an old thread with the same problem I have and not be resolved or updated LOL.