I'm new to the Forum and love driving fast cars and the 2004 C5 I purchased. I'm no mechanic but not too dumb about it either. I am having some issues with the Vette I purchased that I'm hoping someone can help me with. This car has been worked on and has a 383 stroker and a ton of extras. Before I purchased it the used car dealer took off the supercharger and where I live we have inspections. they could not get the O2 sensors to communicate to the computer and we found the wires cut. They fixed that, put back in stock fuel injectors, and some exhaust manifold hoses replaced and after performance dyno went and finally got the car to pass inspection. The car dealer is now closed. Now I keep getting reduced Engine Power. I can get the codes and the first time was the Throttle positioning sensor. Replaced that and that code is gone. then I got a new code with Reduced engine power of the MAP sensor. Replaced that and that code has not come back. Now I'm getting a P0120 and P2135 and looks to be the throttle position sensor and the readings from the TPS which has already been replaced. I'm at my wits end. Can someone recommend what steps I should take next. any help would be greatly appreciated.

 

Welcome to the Forum, and congratulations on your C5!
If you have not already, I would recommend posting this in the C5 Tech section, too. https://www.corvetteforum.com/forums...s-1997-2004-2/.
Here is info from an old service bulletin that may help, but there are some great members with more tech skills than I in the C5 section.
Best wishes with an simple fix!

2003-2006 Cadillac Escalade

2003-2006 Chevrolet Avalanche, Corvette, Express, Monte Carlo, Silverado, SSR, Suburban, Tahoe, Trailblazer

2003-2006 GMC Envoy, Savanna, Sierra, Yukon

2003-2006 Hummer H2

2005-2006 Pontiac GTO

Equipped with a 4.8 5.3 6.0 or 7.0 V-8 Engine

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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
A vehicle may be brought into the dealer for a reduced power message, and DTCs P0120, P0220, P1516, P2101, or P2135.

The Throttle Actuator Control (TAC) / throttle body type trouble codes, may be caused by a loose wiring crimp at the throttle body connector, or a broken throttle body circuit.

Recommendation/Instructions:
Complete the current SI diagnostics for any symptoms or trouble codes found. If a intermittent T/P or TAC module type code is occurring complete the inspections below.

Inspect all related throttle body terminals for a loose wiring crimp. The loose crimp may be difficult to find, and the poor connection will be between the terminal and the copper strands of the wire. Wiggle test the individual throttle body circuits to see if the concern can be duplicated.
Inspect the related circuits for broken wires inside the insulation. The outer wire insulation may look fine, but the internal copper strands may be partially broken. Breaks in the wires usually occur within 1 to 4 inches of the throttle body connector. Wiggle testing may also induce a trouble code to set.
On C/K trucks complete SI procedures for voltage drop on grounds G103 and G104. Grounds G103 or G104 may be loose or corroded.
If a terminal crimp or a broken wire has been found, repair or replace only the circuits involved. There is a throttle body pigtail connector available through GMSPO, but installing this pigtail connector may cause other intermittent TAC module/TP codes at a later date. If this pigtail must be used, please follow the SI procedures for Splicing Copper Wire Using Splice Sleeves. (the proper Kent-Moore crimping tool must be used for this repair)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.