imdrax

iTrader: (1)

im currently trying to resolve an idle issue as well as a flooding issue. anyway i got to the point where i started to test my tps. i had the car warmed up but then it sat for about ten minutes afterwards before i started doing my resistance checks. i got 5K at idle and OL at full throttle(on a 20k scale). im sure because my car was not "fresh out of the oven" my readings are off. i will mess with that later. my REAL question is, is the TPS "rod" supposed to be fully extended at WOT or sometime before? at closed throttle position my TPS "rod" is approximately halfway extended outwards and near 1/4-1/3 throttle the "rod" has fully extended outward. is this normal? so if the rod fully extends by the time im at 1/4 throttle theoretically the ecu will adjust fuel trims as though im at WOT right? or am i completely missing something. i fiddled for a good hour trying to figure out why the rod is fully extended by the time im at 1/4 throttle. i took the nut off of the throttle linkage shaft and dismounted the "lever" that contacts the TPS "rod" and i could not figure out a way to make it so that the rod is fully extended at WOT instead of 1/4 throttle, and as far as i can tell it does not look as though ther IS a way to make it so. So how does my ECU differentiate WOT from 1/4 throttle is the rod is fully extended at both throttle positions?
PICTURES(sorry they suck)
http://pg.photos.yahoo.com/ph/imdrax...66.jpg&.src=ph
http://pg.photos.yahoo.com/ph/imdrax...8e.jpg&.src=ph
http://pg.photos.yahoo.com/ph/imdrax...68.jpg&.src=ph

Wanked_FC

iTrader: (1)

im gonna assume this is an s4. the ecu only uses the tps for on/off thorttle transitions once you are above 1/4 throttle. its a narrow range tps (ie above 1/4 throttle its not used at all). the only way to adjust it is with that screw.

imdrax

iTrader: (1)

ok that would make sense. now im wondering why my resistance values are so incredibly high? would that indicate a failed TPS? my FSM states that at idle position resistance should read at 1k ohms and at full open throttle resistance should be at 5k ohms +- 1k ohms. but at idle im getting a resistance reading of around 5k ohms and if i slowly open the throttle the value keeps increasing 7k, 9k, 12k, 15k, until it maxes out on the 20k ohms setting. this would definately indicate a failed tps am i correct?
*and yes this is an 87 TII*

slpin

iTrader: (9)

check your wires on your ohm meter
i think it is your ohm meter

imdrax

iTrader: (1)

i get perfectly fine voltage readings and i have just previously tested the BAC valve and it was within spec so i dont think i should have a problem there but i will check. on another note i saw a picture of the 2 tps' that the S5 uses so what does the ecu on an S4 use for throttle position for anything over 1/4 throttle?

slpin

iTrader: (9)

s5 uses a tps that only works up to 1/3 too

the big fullrange tps is for the eomp.


you do not want eomp

imdrax

iTrader: (1)

so what is the computer using to differentiate between 1/4 throttle and WOT? Im going to take the tps off the car tommorow and use one of my friend's DVOM and see if i am getting the same resistance values. and if i do im going to toss it.

Mint87RX7

dont even worry about the resistance, the computer just sees voltage. its sending 5v to the tps and seeing what comes back. what you need to worry about is if there are any dead spots on the internal resistor or the tps, you at least need an anolog voltmeter and ohm meter to see the clean sweep.

NZConvertible

Nothing. The S4 ECU isn't that sophisticated. It doesn't need to know what's happening beyond 1/4-throttle because it's not programmed to do anything with that info. This is perfectly normal for older EFI systems. Some only had a throttle-closed switch.

Are you unplugging the TPS from the loom before you measure the resistance? If you don't it'll screw up the readings.

If the resistance is okay, check the signal voltage. Leave it on the car and plugged in, and with the igntion on and the engine hot, measure the voltage between the green/red and black wires. As you open the throttle it should sweep smoothly from 1V (closed) to ~5V (TPS at full extension). If it doesn't start at 1V adjust the screw until it does.

imdrax

iTrader: (1)

yes the tps is disconnected. and like i said resistance is very high. i am going to try it with a different DVOM tommorow and see what i get. and mint resistance is obviously VERY important because if the ecu is sending a 5v reference the signal it recieves back from the tps is completely dependent on said 5v as well as internal resistance because it would directly affect the signal being sent back to the ecu therefore giving the ecu false presumptions if the resistance was way out of spec.

eoph

so does that mean that if one wants to be lazy they can just use 1/4 throttle instead of full throttle when trying to drive fast?

NZConvertible

I don't know where you got that idea from but you couldn't be more wrong...

HAILERS

The resistance sounds out of whack, but.....It would be interesting to connect it to the harness, and with a fully warmed up car, backprobe the Green/Red wire at the connector (harness side) and see what the voltage is at idle (approx 1vdc and what it reads when you hold the throtte wide open ( somewhere around 3.6vdc from memory).

imdrax

iTrader: (1)

i will give that a try tommorow after i put it back together. so i am going to want to warm the car up to op temp then quickly shut the car off and remove the TMIC, backprobe the top wire(grn/red) and put the - lead to a good ground? or the B terminal(black/red)? WITH the harness connected correct?

imdrax

iTrader: (1)

obviously not becaseue although the tps range is 1/4 throttle the airflow meter whatever kind it is(not sure) is still calculating the amount of airflow being sucked in which is a direct result of how far the butterflies have opened, and that in turn will deterrmine how much fuel is needed to match the airflow.

HAILERS

With the meters positive lead up the backside of the green/red wire with the connector connected. The negative lead either on the battery negative terminal or some other ground like the BODY of the alternator or one of the rotor housings.

The car needs to be fully warmed up as in HOT. The reason is the trottle linkage is connected to the fast idle cam/thermowax and will move as the engine cools. When the linkage moves.....it changes the tps reading. That is why the manual tells you to fully warm up the engine before setting the tps.

Or if you had access to the ECU you could put the meters negative lead on one of the ECU mounting bolts and put the meters positive lead up the back side of the pin 2G of the middle plug on the ECU. It is a green/red wire. It's the other end of the one on the tps. With the engine idling you can read the tps output there. It should be approx 1vdc at idle. If you do it this way you don't have to remove the intercooler.

I'm not saying your tps isn't corrupt from what you said earlier. Just check the output to the ECU or the output from the tps at the tps plug.

imdrax

iTrader: (1)

alright i might try that. ive read about doing it at the ecu in order to get an accurate reading of what the ecu actually sees. WHere is the ecu located? will i have to remove dash panels to get to it? i just used a 3RD ohmmeter on the tps and with it sitting fully extended on the bench it will vary from 13k ohms to 22k ohms. and if i depress the rod slowly it will hit OL at certain spots throughout the range on each multimeter. i can although get it to stick steady at 1k ohms when the rod is near closed. but the fully extended readings as well as the linear readings are what really worries me. how would these extremely high resistance readings affect driveability? could this cause my flooding on startup and bad idle?

HAILERS

ECU is under the carpet where the passenger puts his feet. There is a metal plate covering the ECU under that carpet. It's a bit of bother to pull the carpet up then the plate etc.

Maybe you could rig something up. Like install a seperate wire in the back of the green/red wire at the tps plug. Make it a foot or two long and run it to the left side of the engine where you can get at it with the intercooler on. You'd have to make sure that its end does not touch ground/engine/chassis, though.

Then you could warm the engine up and have the meter on that wires end and see the voltage. As for adjustment of the tps, I use a common screwdriver about three feet long. Gotta be careful to not touch the alternator *B* terminal though. I've done that. Pops the 80amp fuse in a hurry.

From your description of the tps readings....it sounds like its shot.

imdrax

iTrader: (1)

yeah that sounds like a good idea. what i did before was left my + lead in the back of the connector and installed my intercooler. i got somewhere around 1V but i cant remember exactly and i didnt go full throttle to watch the changes. but lets say tommorow that i test it out and i get ~1V at idle and ~5v at WOT then what would explain my very odd resistance values?

HAILERS

Move the throttle pedal slowly and see if the voltage drops when it should be going up and vive versa. I can't explain your resistance readings except for a bad tps.