LQ4-E39

iTrader: (7)

i am trying to figure out my idle issues before tuning tomorrow.

background: http://www.hptuners.com/forum/showth...6-in-a-BMW-540

TPS reads 4.98V with key on and engine off. surely this is wrong.
i am also getting 89%TPS at Key on engine off with my foot off the gas.
TPS drops to 31% with foot to the floor. throwing codes for MAP sensor which has to be getting bad readings from the high idle (2200 rpm regardless of condition).

i am hoping i just have a few TPS wires backwards. any input is appreciated as i have a tuning appointment for 1pm tomorrow and don't want to bog them down with my wiring issues.

LS1-450

iTrader: (33)

4.98v is correct. It reads from 0-5v. I'll be back in a few minutes. Am gonna look @ a wiring diagram for correct connections.

LS1-450

iTrader: (33)

OK, swap blk/gry wires on TPS. MAP code may just be a result of TPS issue. If MAP code persists leave gry on MAP sensor alone & swap other two.

SSellers

Sounds like you have the ground and power swapped but the sense line is OK. Then it will need a calibration.

SSellers

Whoops, I was typing on an unrefreshed page Frank.

LS1-450

iTrader: (33)

BTW, had assumed that you have already zero'd the TPS & confirmed the throttle cable/pedal/throttle body related positions.

curbcheck

i saw your other thread and thought you had it figured out already. your build thread was one of the better documented ones ive seen since joining.

Project GatTagO

iTrader: (7)

I've never heard of LS TPS sensors having to be calibrates. You probably have the power and ground crossed. Once you flip the leads, the sensor will be calibrated automatically at start up.


Andrew

LQ4-E39

iTrader: (7)

shortly after posting this thread i thought about the logic of my problem and looked at the pinout again. signal, low reference, and 5V reference. i swapped the 5V reference and low reference and the inverse problem was solved. now had 6% to 60% from no throttle to WOT, which was good, but the range was not big enough. even after recalibrating (reset) the TPS and making sure everything was connected correctly, still had 60% at WOT. turns out the Express Van TB has what seems like a thicker cast aluminum stop for WOT, so i machined down that stop little by little until we were getting better readings. final result was about 4% to 95%, and started tuning from there.

made 370whp/374tq

LS1-450

iTrader: (33)

Glad you worked it out & didn't lose your dyno time to trouble shooting.