Hello all,

I realize there are tons of threads about this issue, however I haven't found an exact solution.

I have a 2004 C5 that I recently had a complete build done on, including an LS7 swap. I am having an issue where every time I punch it even with traction control off, it goes into Reduced Engine Power mode. I spoke to the builder who said that it's because we need to put an LS2 throttle body in there. Complete transparency, I just drive it, I definitely don't work on them, so when he gave me his rationale, I didn't fully remember all the details.

He sent me a link to the Texas Speed LS2 throttle body but its another $600.00. Reading through threads, I have yet to come across one saying this is a fix for it. Before dropping another $600 for the throttle body and $300-$500 to retune it, I would like some opinions on whether this is an actual fix?

Any help is much appreciated. Thank you in advance.

 

Whatever throttle body is on your LS7 your OEM TAC Module is looking for certain voltages from your TPS and APP sensors and if it doesn't see them you will most likely get a REP.

 

So if I understand correctly, there is no guarantee that the LS2 TB will be the fix if the TAC is not receiving the OHMs it needs?

 

Can’t guarantee and it’s voltage…ohms is resistance…if you start swapping in non OE parts your going to have problems!!

 

I see, well I thank you for your reply. Nauseating to spend $600 and it not be the fix. May sit on this for awhile before I pull the trigger. Thank you again sir!

 

I’ve seen members here with LS2 TB’s and some work and some don’t…it seems like they have to rewire these TB’s.

 

I talked to Texas Speed tech support earlier and they claim it has to do with the blade color and that I would need a silver blade to work but he couldn't give me the technical details to back that up so I am left in the dark.

 

Just use some silver spray paint if that’s all that it takes to work ??…LOL !!

 

Touche sir haha Touche!

 

FWIW....I think the boards/internal wiring are different on the gold to silver TBs. I know you're joking, Rob!! And it's funny!!!! Anyway, In 2005, I put together a 427 Darton engine. It used a silver bladed LS2 TB, which I'm pretty sure was the only LS2 TB available then. GM changed the TB sometime after, and from everything I've read and heard, the later TBs used a gold blade. Those TBs don't play well with C5 electronics. I could be wrong, but that's how I remember it. Dont know why GM does this crap. IIRC, they did the same thing with the LS7 TBs, earlier style was silver bladed, later ones were gold. I have the silver blade in my LS7 equipped C5, and have been told the gold ones won't work well, if at all. For all I know, the LS2 and LS3 may use the LS7 TB. They're all 90mm..

 

I believe you are correct my friend. I have talked to some of the most mad scientist LS7 folks I know today and they concur with what you are saying. Time to drop some more coin. Hate to do it, but if that is the fix then I am all for it.

Thank you guys again! The Corvette family is always the most helpful folks around!

 

My 2005 was having the reduced Engine Power, and sometimes Service Traction Control warnings. Code reader indicated Throttle position sensor issues. The car is 18 years old, but only has 27,000 miles. I didn't want to believe the sensors (gas pedal or throttle body) were bad given the low mileage. Reading through the posts on thius issue it seemed the culprit would be one or both of the sensors.

Cleaned the throttle body hoping it might be sticking (unfortunately on the 05 the sensor is built in and can't simply be replaced). Didn't help. though it's very clean now. Tried to order a new pedal with sensor as that is the cheaper of the two parts... but couldn't find one anywhere.

I ran across a post that said someone had brought there's into a shop with this same issue and were surprised when the shop was able to solve the problem with a simple fix. The shop cleaned the contacts on the sensor connection.

I read up on electronics contact cleaners for high end audio equipment and such. Ordered some D%S-6 CAIG Deoxit 5% Spray Contract cleaner for under $20. At that price figured it was worth a try. I disconnected the Gas Pedal sensor connection and the Throttle Body sensor connection. Sprayed both, reconnected both, then disconnect both one more time as the product instructed, sprayed them one more time and reconnected them (Lots of fun on the Gas Pedal as I chose not to unbolt the pedal and just work the connection while the pedal was in place).

400+ miles at all kinds of speeds later - no more errors!! Prior to the contact cleaning it was going into Reduced Engine Power errors after only a few miles, so the connections being cleaned seems to have done it. For good measure I did hit the gas pedal spring mechanism with some WD40 as I was under there anyway.

Hope this might work for others. Definitely better than an expensive Throttle Body swap, and for the 05's the hard to find Gas pedal and sensor.

 

Dont do that yet.

The gold blade (ls3/ls7) throttle body opens slightly different than the silver (ls2) throttle body. People have tested and found recently that reducing the max throttle opening slightly in the tune solves the issue. Ive seen 95% or 96% something like that but you could just start at 90 to make sure.

I would try that small change before dumping $600 on a new TB