Thread: What happens inside the ecu with TPS disconnected?

I was double checking my idle/timing the other day and I noticed it revs up way more stout with it disconnected! It has way more response.

I thought all the ecu did is disable the IACV...... So you can set the base idle speed.

I ask because I have this 90mm TB on my setup.

If I tried to drive it, what would the ecu do/limp mode. It still see's RPM and load from the MAF.
I was just wondering if it might drive better like this with my monster TB.

I don't understand why its better John/Dave. Should I disable alpha n mode in my tune?

From what I can remember before my new intake manifold and TB with the TPS disconnected and setting idle/timing, it revs up kinda crappy. Once TPS is connected it was back to normal.

With TPS unplugged, if the trans is in neutral and the ECT is at least 140ºF, the ECU enters "SET IDLE/TIMING" mode. If the trans is in gear and the vehicle speed is above 2.5mph, the TPS DTC (code 43) is set. Also, load and RPM are used to determine whether the throttle is open or closed.

In "SET IDLE/TIMING" mode with the throttle closed, idle PWM is fixed at "IDLE DUTY" and the ignition timing is fixed at "BASE IDLE IGNITION" . (See SETUP, EXTRAS, DIAGNOSTICS screen.) If the throttle is open, the timing map is used and all other ignition trims are applied.

Also, since the TPS sensor isn't responding, accel fuel trims are not applied.

Well all that is good to know! Thanks Dave!

Now, you say if the throttle is opened (unplugged) it still uses the timing map and all other timing trims BUT how does it know if the throttle is open? (there is no tps plugged in) because of the maf load increase or rpm increase. I wanted to make sure I got this right lol.

So driving with it unplugged will only cause a loss off tps related accel trims only? Makes sense because lots of people forget plugging it back in after setting timing

Would it also not use alpha-n without the tps signal?

Just wondering if there is more to what I noticed because its more responsive rev'ing in "set timing mode".... Maybe ill play with the tps accel fuel enrichment stuff and see what happens (note. enrichment seems fine while driving)

Check bold sentence.