Hey everybody,

Ive recently been having issues with my ‘04 z06 going into reduced engine power, I’ve reset the TPS and pulled fuses as well as replacing the TAC and TPS and cannot find the issue any suggestions?

Josh.

 

Use the Drivers info Center to pull codes the next time it happens.
There will be a code in there that likely will give some clues......

 

Josh,
WELCOME to the Forum !!!...as was mentioned post up any DTC's (codes) you have...I can see you already fired the parts canon without much success...is the reduced power message all you are seeing ??...it may also be your APP sensor but without some trouble codes it may be difficult to diagnose...did you check the wiring at the TPS or at the TAC module ??...unfortunately these things don't operate wirelessly !!...if you have 2 or more DTC's set involving more than 1 APP sensor (there are 3) you will only see the REP !!

 

C5 Diag is sending you down the best path. First find all DTC’s (Diagnostic Trouble Codes). That will send you in the direction of where to start your diagnosis. Think of the DTC’s as taking blood pressure, finding it to be high, then the Doc goes through a diagnosis to find the root cause of high BP. No doctor will perform surgery just from BP. Likewise, firing a parts cannon at a DTC seldom fixes the root cause.

In fact, there are problems that result in reduced power that will not throw a code. For example, if the knock sensors sense spark knock, the PCM will command spark retard with no code. There are DTC’s for KS circuit failure, but not activation. The bad news is the a failing motor mount, a failing pilot bearing, can send a signal the KS thinks is spark knock. If the crank sensor is off just a bit (needing re-learn) you will get random misfires that will also affect performances and not throw codes.

Please don’t conclude you need new motor mounts. My point is more trouble-shooting is needed on your car. It may very well be a$10 part will fix it. Replacing the correct $10 part is the secret.

 

These were issues I had previously and could not figure out, I took it to a professional shop and they went through the TPS, found it was the TAC and replaced it then the TB motor was out so I replaced that as well. It worked fantastic for a week and it’s back to going into RED. Power. The codes only usually get thrown when I punch the throttle or go down my bumpy driveway. It’s possible that because I purchased a used TAC and TB they went out? When I get home I’ll go through the codes and post them up here.

Josh.

 

We would all like to help you, so help us a bit.

What codes are thrown?

What message displays on the DIC (Driver Info Center. bottom center of the instrument panel) exactly when the car goes into reduced power mode?

Now regarding replacing the TAC and the TB motor at the same time, This description rather suggests the wiring between the two, and the PCM have an intermittent short or open. Then , going over a bump or pedal to the rug would be enough movement to open or short the wire(s). Not saying this is the case, but two related components usually do not fail at the same time.

 

These are the codes and messages I am getting on the DIC.

 

P0141HC This is the heater circuit for the second O2 sensor on the drivers side (Bank 1 Sensor 2) So something is wrong with the heater circuit for this sensor. Often someone that is fiddling with the O2 sensors will not put the harness back in place and either the wires or the connector are melted. Do you have headers? I don’t think this would cause the problems you are describing, though.

P0530HC Air Cond pressure sensor circuit.

P2101H see this thread, post #4 .

https://www.corvetteforum.com/forums...-p2101-hc.html

I think your APP is not talking to your TAC correctly. This is probably the bogey that is causing your symptoms. You may have a wire in the circuit that is open or shorted. Though usually there are circuit monitors in the PCM that should lead you in the direction of the problem circuit by throwing circuit DTC's. Or, the replacement that was done was the wrong year. Several possibilities here, but to solve this you are going to need to use a multimeter. If you can look at 2 channels at once that will help. One circuit goes up as the other goes down. Also a good place to use a labscope.

Your bumpy driveway and pedal to the rug causes still has me thinking intermittent short/ground of the wires. If so you will have to ring out all wires, and go on a mission of shaking harnesses to repeat the failure. I think the routing of the harness that contains these wires runs behind the engine and there is one retainer that holds the harness to passenger side cylinder head that few mortals can reach. However to be sure if someone has the pages of the FSM with harness routing you will need that info.

The P0530. Since this is your air cond system, you might discount it. BUT, this sensor is not all that far from the other circuits giving you trouble. All the wiring and AC system stuff are on the passenger side of the engine. And they may route in the same conduit. I don’t know exactly where this sensor is, but maybe someone else does. It would be a short bit of work to at least chase this one briefly to see if it leads where the APP/TAC/TB wires go. Mice love wire insulation, so if you see evidence of mice at all or smell them, you are in for electrical problems. You are going to need the wiring diagrams and the knowledge to read and understand them. If you are going to turn this over to the Pro that did the swaps you describe, he rather sounds like a parts changer than a diagnoser. If that is the case you are in for more parts swaps and grief. If you go back to that pro I would certainly ask what he found that led him to conclude you needed the parts he replaced. If he said he changed them because of the DTC (Codes), he may be the wrong guy for your situation.

B0333HC Your outside air sensor is not giving a signal.

Service Traction system. A consequence of P2101

Service Active handling Ditto

 

Yes I do have headers with full exhaust, the place I took it too went through the previous codes and thought that was the cause. It worked great for a week and went back to going into RED. They also said they checked wiring as well but I’m not sure how much I trust them anymore.