TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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I think i´ve got a problem with my TPS ?! In idle, the voltage is 0,56 V. That´s Ok. The car runs very well. But in WOT, I´ve just got the voltage 4,32 V.
I think, it should be 5 V ?!
Can you help me ? What´s the right voltage in WOT ???
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88´Pontiac Firebird TransAM 305 TBI A/T
New painted and built to Knight 2000 exterieur replica in 2006/2007. Cowl induction hood coming soon...
Ported 081´heads, 46mm bored Edelbrock 3704 intake manifold, ported throttlebody, open filter element, LT1-cam, Edelbrock valvesprings, Edelbrock true timing chain, ACD241 fuelpump @18 PSI, EBL, headers, Flowmaster 80 muffler, high flow cat.
Black interieur with black PMD-leather seats...
The 4,32 volts at WOT isn't too far off. The TPS won't, and shouldn't, go to 5,0 volts at WOT.
First thing to check is that the throttle is actually going against the stop on the TBI. Floor mats are an issue which will prevent true WOT.
If you open the TBI by hand at the TBI unit, you will note that there is a stop. This is true WOT. Now go around to the drivers door and reach in with your foot and press the go-pedal. While doing this watch the TBI and see if it goes to the stop.
If not then need to check the floor mat. Sometimes need to remove padding from under the carpet.
The 4,32 volts at WOT isn't too far off. The TPS won't, and shouldn't, go to 5,0 volts at WOT.
First thing to check is that the throttle is actually going against the stop on the TBI. Floor mats are an issue which will prevent true WOT.
If you open the TBI by hand at the TBI unit, you will note that there is a stop. This is true WOT. Now go around to the drivers door and reach in with your foot and press the go-pedal. While doing this watch the TBI and see if it goes to the stop.
If not then need to check the floor mat. Sometimes need to remove padding from under the carpet.
RBob.
is that something the computer handles and keeps it down?
is that something the computer handles and keeps it down?
Not really, the ECM only reports what the sensor sends to it (as a voltage).
One reason that the TPS voltage is never supposed to be at 0 or at 5 volts is that they are the ends of the possible range. Which are used for diagnostic purposes.
If the ECM reads 0 volts from the TPS, then it knows that something is wrong with the reading. Same for 5 volts. Something is not correct. One will throw a code 21, the other a code 22.
OBD originated from GM ECMs. Which really do help. Nothing worse then having a bad sensor that the ECM doesn't know is bad. Note that the on board diagnostics also pick up items such as disconnected sensors, and open or shorted sensor wiring.
GM also has code that will create default values for some sensors. This can be good enough that it is hard to tell that you have lost one (other then the SES light).
What would be the benefit,if any, with having tps set to 0.70 at idle? Mine is there and at WOT it hits 4.31 V Max.
Doesn't matter. As long as the TPS is between something like 0.2 V and 0.9 V it will work. The ECM auto-zero's the TPS to provide 0% TPS at idle.
One thing that I do like to set up is the TPS% gain. This calibration parameter is used to convert the voltage to a percentage. Set it so that WOT just gives 100% (TPS%).
Note for others that are not TBI, the MAF TPI ECMs are different. They must be set to 0.54 volts to work correctly.
'90-'92 TPI cars and the '90-'91 MPFI cars are in the same auto-zero category as the TBI cars.
