Faulty TPS

awd-drifter · 02-03-2010

Hey all. I'm wondering if I have a faulty Throttle Positioning Sensor or another issue. It seems that everytime the car is fully warmed up, after I put it into neutral before a stop and the car wants to die. It doesn't even stay on idle.

For example; the car is warmed up, come to a stop sign, throw it into neutral and the car will immediatlely lose rev and die and the only reason it doesn't die is if I give it some gas, than it will keep idle (kinda used to doing this now and not letting the car die by itself). The reason why I'm suspecting the TPS is because I've replaced the ISC already, triple checked my vacuum lines (no cracks), no boost leaks. The CEL also comes up when I'm in 'cruise control' and then when I drive, the CEL disappears when I let go of the gas pedal (car is still in gear and moving at highway speed). So, could this be a faulty/dirty TPS?

**asshanson** · 02-03-2010

I have this problem too if I let the RPMs drop from too high, so now I let it rev down to about 1800 while coasting and it catches at 1500 pretty easily.

But I didn't have this problem until I got a big turbo and intake pipe, and super light flywheel, apparently the DSMlink v3 MAF clamp helps fix the issue.

You should be able to log TPS volts, should be .63 at closed and between 4.5 and 5 WOT if I remember correctly.

awd-drifter · 02-03-2010

i don't have dsmlink

or anything to check the tps volts. does oreily or any other shops have the tools to do this?

96GST16g · 02-03-2010

got a voltameter?

4g63tcrazy · 02-03-2010

Check vfaq.com for info on how to check it.

lucasoil4u · 02-03-2010

yeah its not that hard just use a voltmeter and make sure that it doesnt have a spike or anything crazy. should be a nice smooth ramp up..

**Shane@DBPerformance** · 02-04-2010

Quote:

Originally Posted by awd-drifter

i don't have dsmlink

or anything to check the tps volts. does oreily or any other shops have the tools to do this?

Do you have an AFC? That will show TPS voltage.

awd-drifter · 02-04-2010

I have an s-afc. I will definately check it out.

awd-drifter · 02-05-2010

well, according to the s-afc, it says .510-.505 on idle. I haven't tried to make the car die because I just don't like the fact that it dies while I drive. Also, when I'm parked (after a warm up/short drive) I let the car idle and it drops revs to 500-600 than it finds idle again and than idles perfectly fine afterwards.

4g63tcrazy · 02-05-2010

Your AFC should show throttle in % also. See if it's reading the right %. Just turn the key to the ON position and watch the throttle in percentage and go slow from 0% to 100% and make sure it's nice and smooth.

**Shane@DBPerformance** · 02-05-2010

You TPS voltage with the throttle closed should be .61v-.63v. You can't use the throttle % on the SAFC to tell you if the throttle is set right, it is a learned range. Your volts could be 1.5v at idle and 3.5v at full throttle(which isn't close to right for a DSM) and it would learn that to be 0%-100%, but you could use it to make sure there aren't any dead spots or flaky readings as you slowly move the pedal from closed to full open.

awd-drifter · 02-05-2010

yeah, the throttle % is at 100%(closed) when at idle. Volts still showing .510-.505 for the throttle sensor. Seems like those numbers are lower than usual.

**asshanson** · 02-05-2010

Adjust the TPS position then so it reads .63 at idle.