TahitianEG

iTrader: (1)

What could be causing the problem? I have replaced my TPS 3 times in the last year. All with used TPS's but they were functioning fine, as far as I knew, before I installed them. I am running an OBD1 B series motor.

On a side note, and possibly related, I'm running VERY low Idle RPM. Once my motor is up to operating temperature my idle is around 100-150 rpm. It has stalled out a couple times. I'm also running a stock JDM P30 ecu, so the fuel map is a bit more rich than a USDM one.

If memory serves me correctly, on a recent compression test, I was at approximately 14 psi (across all 4 cylinders) at like 200 feet above sea level.

Edit, Probably 140 psi not 14


Modified by TahitianEG at 3:34 PM 8/6/2007

VRD^don

did you adjust the TPS to 4.5volts? have you try a new TB?

TahitianEG

iTrader: (1)

Ive heard people talking about testing the voltage of the TPS, but I never knew why. I always thought it either works or it doesn't. So with that said . . .

Why does the votage matter? What would a change in voltage do?
How do you change the voltage?

Blk00EJ8

Well, having a mis-reading wouldn't hurt the sensor, but the ECU would incorrectly adjust the AFR thinking that throttle is open. That would account for your crappy idle, but there is no way its 150 rpm. Anything less than 400 would be a stall. Don't believe your analog tach since those things are off all the time.

Secondly, 14 PSI across all cylinders would mean your motor is beyond dead. Even a reading of 120 PSI indicates really poor compression. So get that checked again... unless maybe you mean 140..?

Getting back on track, adjusting your TPS to provide 0.5 volts at 0% throttle and 4.5 volts at WOT would allow the ECU to accurately provide fuel to your engine. You basically loosen the two bolts holding the TPS to the TB and rotate it until you get the correct reading at 0% throttle. Slowly open the throttle butterfly and there should be a linear progression to 4.5 volts at WOT. If there are any flat spots or erratic readings, the TPS is dead = get a new one.

Other than that, not adjusting it shouldn't kill it unless you miswired something and the TPS is receiving more than 5 volts. If it's wired to a 12 volt line then that could explain it. Although even then I don't know how your ECU would interpret that if that was the case... I assume there would be some over-voltage protection on the ECUs read pin so any reading above 4.5 would be interpreted as WOT... that could explain why you're stalling out. Waaaaaay too much gas at idle...

TahitianEG

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Blk00EJ8 &raquo;</TD></TR><TR><TD CLASS="quote">Don't believe your analog tach since those things are off all the time. </TD></TR></TABLE>

Yeah it's probably around 400 but it's WAY too low. I give it a little gas to make the idle climb and it coughs/stutters/bogs before climbing up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Blk00EJ8 &raquo;</TD></TR><TR><TD CLASS="quote">adjusting your TPS to provide 0.5 volts at 0% throttle and 4.5 volts at WOT would allow the ECU to accurately provide fuel to your engine. You basically loosen the two bolts holding the TPS to the TB and rotate it until you get the correct reading at 0% throttle.</TD></TR></TABLE>

There is counter/clockwise movement that is possible on the TPS once it's mounted? I'll have to take a look at that. Then I'll adjust is as needed.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Blk00EJ8 &raquo;</TD></TR><TR><TD CLASS="quote"> Slowly open the throttle butterfly and there should be a linear progression to 4.5 volts at WOT. </TD></TR></TABLE>

I'll check the Voltage asap

Thank you for all the insight. I owe you a

Blk00EJ8

No problem. Good luck