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[Omegafantasy]

Hi all

Just a quick question: What is the reported max voltage from your TPS at wide open throttle? Either by direct measurement or tech2/"My Naff Code Reader".
I would think 5 volts should be max, but mine can't reach more than 4.4V (83%). I would just like a reference 

Oh, forgot to mention that this is for Motronic M2.8.1 (X25XE/X30XE).

[Andy H]

Yea! maybe you are actually on to something.

IIRC the throttle cable is adjustable by means of a spring clip and a series of grooves on the outside of the throttle cable where it attaches to the throttle body.

Does pushing the pedal to the floor fully open the throttles?

I have just checked what my car reports and found that pedal to the floor gives 100% . (It is a 2.6 DBW and I used VAG-com so may not be directly comparable).

[Omegafantasy]

Thanks Andy

The throttles open 100% (checked visually), but the TPS won't ever report more than 83%. Also measured directly on the TPS with ignition on. +5V is fed into it, ground is proper, but output never above 4.4V. Tried to unscrew it yesterday, but the bottom screw got a bad head so I have to remove the butterfly assembly and use some other tools. Think I have a spare (or two) sensors I can throw in.

Hopefully it's that easy. It would at least shape up the fuel mixture and hopefully give me more "oomph" I do, however, think I have a partially blocked exhaust with a small leak in front..

[TheBoy]

I'm not sure it goes to 100%.  The ECU will likely learn the range, based on MAF/Lamdas/TPS/RPM/Speed

[Omegafantasy]

Yes, it could be  :-/
I will just have a little faith that this is the problem, change the sensor and see the results..

[Kevin Wood]

The throttle pot will always have a little more travel than the throttle itself, so you will find about half a volt "missing" from either end of the range. Your voltage readings sound normal to me.

The ECU will learn the range of the sensor output and calibrate this as 0-100%. I'm a bit surprised that yours doesn't read 0-100% in the live data but I can't recall is that's normal for this ECU.

Kevin

[Omegafantasy]

I don't know what's normal here. I will at least try to change it and see what happens. If I only could dig up some reference data somewhere.. I don't know anyone with a V6 miggy

There might be ways for the ECU to adapt, but then again, it would never know when I open the throttles 100%. The only "commanding" variable the ECU sees is the TPS. IAT, O2, CTS and MAF will only affect the fuel and ignition and as far as I know, they wouldn't know if I open the throttle all the way or not.. Or did I miss something?

Second thought: If the deviation is a preset (90 degrees?) and it starts off at 0%, then 83% would be max. If it starts at 10%, 93% would be max?

I have no idea, just thinking as I write. Would love to see some reference data

[TheBoy]

If I get time, I'll check my 3.2 and 3.0 later this afternoon

[Omegafantasy]

Splendid! 

[Omegafantasy]

Did a little test tonight to see what I could do to the TPS. After a lot of cursing I managed to get the small bolts out. With "My Naff Code Reader" connected I could turn the TPS from 0% to 95% at max.
But it back together with new bolts and adjusted it a bit up (there's some slack for adjustment, a tiny tiny bit). At idle it sat at 8% and would move up to 93%. The car ran fine, probably a bit better, but it had serious idle issues. When releasing the throttle after revving it, it would stay up at 4k or so for a while, but settle at 800.

Obviously not the way to go, it has to idle at 0%, but then it won't reach more than 83% at WOT.

My other TPS was of the newer sort (different plug) so it won't fit. I do have some spare connectors that fit though..

[Broomies Mate]

Did a little test tonight to see what I could do to the TPS. After a lot of cursing I managed to get the small bolts out. With "My Naff Code Reader" connected I could turn the TPS from 0% to 95% at max.
But it back together with new bolts and adjusted it a bit up (there's some slack for adjustment, a tiny tiny bit). At idle it sat at 8% and would move up to 93%. The car ran fine, probably a bit better, but it had serious idle issues. When releasing the throttle after revving it, it would stay up at 4k or so for a while, but settle at 800.

Obviously not the way to go, it has to idle at 0%, but then it won't reach more than 83% at WOT.

My other TPS was of the newer sort (different plug) so it won't fit. I do have some spare connectors that fit though..

I could be very wrong, but is this not something the ECU would learn after a small amount of time and adjust to suit accordingly?

[Omegafantasy]

This is something the ECU will learn, yes, but I had it idling for some time, took a few shorter drives, let it idle again and so on. All this after commanding a relearn of idle control via "My Naff Code Reader". Didn't change anything really, always took some time getting it down.

[Kevin Wood]

You should find a setting called "simulated idle switch" or something in the live data. It's set on when the ECU thinks the throttle is at the idle position. My guess is that, after your adjustment, the ECU is not setting this flag, which means the normal idle control strategy is not invoked and you get a poor idle.

I guess you could try positioning the pot so that this is just "on" with the throttle on the stop. I'd expect the ECU to "learn" where this position is but how long it takes and over what range it will adjust I don't know.

Kevin