Installed the VAFC this weekend with no problems. Soldered the wiring for good connections and even REsoldered some of them just to rule it out as a problem.

Here is my issue:
We started up the VAFC, configured it for the R and no problems. EVerything works just as it should.

Started the engine and the throttle position % readout is all screwy and reads 0.0% if I ease into the throttle. We did chack all connection and the Throttle readout works normally with the car off and screwy with the car running.

2 questions. 1st is there a fix for this or does anyone know what is wrong?
and 2nd if this isn't fixable does anyone know if the jumpy throttle percentage readout will affect A/F ratio tuning on the dyno?

I keep it in my glove box so I don't care what the throttle % readout is unless it affects the ability to tune the car properly.

Thanks

 

why would you think it would affect your a/f readout on the dyno? that should be completely different from what the vafc reads out. so i'd be inclined to say no.

as far as thottle readout i would suggest rechecking your connection if you are getting a constant 0%.

 

I am not inclined to think it would affect it neccesarily but am concerned that throttle percentage MIGHT play a part in A?F calculations the VAFC makes. THis is basically me showing my lack of info on hwo the VAFC works. But before I go doing anything with it I woudl rather have the knowledge.

I have soldered aqnd resoldered the throttle wire 3 times and checked the connection at the VAFC a few times. THe reading is PREFCT when the car is not running and jumps around when the engine is running. The percentage reads out but not steadily when running. ANd when I say jumpy I mean 0.0% to 12.4% to 8.3% to 0.5% to 40.5% all within a second or 2.

 

still looking for some input

Update:

Plugged a completely different VAFC into my harness and it behaves the exact same way. SPoke with Apex-i and yes this is an issue that has to be fixed before I can tune the car with it. Here are my thoughts

TPS is messed up. Gotta get a Voltmeter and test how steady the voltage readout is.

Ground is somehow bad and I am recieving "noise" from the engine and that is why it works normally while the engine is not running.

Possible fixes. Going to redo the ground wires although I don't get why just the Throttle reading is messed up.

Anyone see these problems before or have thoughts from an electronics background?

 

Yet Another Update:

Tried a different VAFC unit on my wiring and the problem persisted. = Not the VAFC unit.

Swapped TPS (Throttle Bodies) with a 2000 I happen to have sitting in may garage and problem persisted. = not the TPS.

Rewired the grounds farther apart and verified connection and problem persisted. = doesn't seem to be the unit grounds.

ANY one have suggestions or thoughts?

 

More Updates:

Talked to Apex and they said we are doing the right things and suggested tracing the throttle cicuit.

I did recheck all wiring today and everything is correct.

Someone please susggest so possibilities as to why when th engine is off the VAFC works fine and when it is running the THrottle output reading is jumpy and never constant.

 

It sounds like it was not initialized properly... There is a step in the initialization where you calibrate the Throttle position by holding the throttle wide open for a few seconds. Have you tried re-initializing it?

Andrew

 

Reset your ECU and try again. Mine was like that in the beginning, but after I resetted the ECU, everything was perfect.

 

When you install the VAFC, you have to do the initial programming before starting it. You have to set the sensors to 6 in and 6 out. You also have to program it to read 4 cyl and the throttle position by moving the highlighted part to the Up arrow on the settings menu. You leave the throttle closed for 10 seconds, the full throttle for 10 seconds while the car is in the ON position, not started. This tells the VAFC where the full and closed throttle positions are. Hope this helps