Hi all, I have a 2002 Z track car that went into limp mode on track after driving it track style....hard. Anyhow, I got several DTC codes pictured below.
My question is for the experts, which I am not, I hooked up my Tech2 and got some TPP and APP sensor voltage readings with key ON, Eng OFF (2) and eng ON(2).
You think these voltage readings would cause a limp mode? THX Brian.

key ON eng OFF

key ON eng OFF

 

 

Hi all, I have a 2002 manual trans corvette with 2002 PCM, LS3 stock engine and LS2 throttle body. I got a few codes P1220 Throttle Position Sensor 1 circuit and so on. At track after about 5 laps car would go into limp mode.

Put the Tech2 on it and got these readings. These are my readings with IGN ON only.
It appears my 0% throttle on TPS sensor 1 is too HI at 1.35volts, but within parameters at WOT at 4.45v.
LS2 TB TPS sensor 1 limits are 0% throttle 0.13v to 0.67v.

My TPS sensor 2 reads 3.67v at 0% throttle, which is too LOW. And WOT reads 0.57v which is within limits.
LS2 TB TPS sensor 2 limits are 0% throttle 4.30v to 4.80v.

Now with ENG running the TPS 1 readings go down to 0.86v at 0% throttle but still too HI by about 0.20v.

Could this cause a Limp mode or other problems? And if so any recommendations on how to fix this?
I have no current DTCs using Tech2, I only got the DTCs when on track romping on it hard.
Battery volts read 13.6 v. THX ALL Brian!


Ignition ON:

IGN ON

Running


ENG RUNNING

TB Voltages

 

Not sure about a C5 but my '87 IROC-Z was in the five to seven volt range if IIRC.

 

This is a good question for a tuner guy. Around 1.09 is idle and 4.32 for WOT is what they claim is good. You're not too far off. I wonder about the condition of the tps, could have an internal fluctuation or dead spot, or maybe lose wiring connection. Or it could be something simple. I'm not sure what the maximum or minimum limits are to throw those codes. someone on the forums should know there are a lot of tuners out there.

 

A TAC module could be the problem if the TPS sensor checks out ok. Sensor 1 below 1 volt closed throttle to above 3.5 volts at WOT. TP Sensor 2 is pulled down to the low reference from around 3.8 volts to closed throttle to below 1 volt. Not knowing what the min and max range is, it could be the TAC module.

 

Yeah I swapped TAC and TB got exact same readings. At 0% throttle the voltages are too low for both throttle position sensor 1 and 2.
It is a gen4 90mm LS2 TB on a Gen3 PCM. Thoroughly confused here.
Is this a tuning issue? THX!

 

Is there a way to measure the reference voltage? I suspect it would be around 5 volts.

 

I would replace the tp sensor and see if that helps.

 

I will check 5v reference voltages.....

I think to replace the TP sensor it means another throttle body. I have tried another exact same TB and came up with same voltage readings....makes me think TB is okay