Basically I've noticed that a small amount of adjustment to A/F can be made using the TPS (common sense, right? confuse the computer into thinking the throttle is open less and it will provide less fuel). But what I'm wondering is whether this method of ghetto a/f adjustment can cause damage to a stock N/A engine? I can't think of a reason why it would. Sure, it'll idle like ****, but that's not really a big deal anyway. Solid idles are for boingers.

 

If you must experiment, at least either have a decent A/F gauge, or continually read the (hopefully good) O2 sensor via a meter.

If you start backfiring ,you'll know the tweaking went too far...

I happen to thoroughly enjoy my rock-solid idle, it definetly adds to the driveability of the car in all conditions...

 

ok...sorry to hijack this thread....but the s4 tps has the on/off setting....is there anyway i can fit the s5 full range tps onto the s4?....i tried searching and found 10+ pages worth of threads but not what i was looking for


sorry....i didnt want to add another thread to that growing 10 pages

 

The tps isn't used for fuel delivery (if you don't count the cutting off of fuel during deceleration). Fuel delivery is a function of the afm.

 

The only thing a biased TPS setting may do is tell the ECU the throttle is closed slightly before it actually is, so you get deceleration fuel cut sooner.

 

Plus a couple of auzillary thing not related to fuel, like telling the Relief and Switching solenoid when to open/shut. It might be Port Air Solenid related also but that's a 20,000 mile and before component and I've forgotten. NZ probably knows about that feature.

 

I'm not so sure about that- just because it's not specific about everything the TPS does in the books, doesn't mean it doesn't work WITH the AFM to schedule fuel...Consider:

1) when the TPS plunger is manually depressed during idle, the idle speed changes. In other words, fuel flow is changed (the AFM hasn't moved during this process)...
2) the TPS voltage signal is of the same parameters as the AFM's signal, which means they're probably used together (along with several other 5v sensors) on the scheduling map...
3) the TPS signal is linear (if the signal was only used for fuel cut and WOT, it would be simpler to just use a microswitch assy)
4) when the TPS is lost, the ECU reverts to a stored setting of 100% throttle (18 degrees, I believe). If the AFM were totally responsible for scheduling, why would the ECU need a specific throttle setting signal?

 

Ok. I'm game. I've a wideband on the car and know a tps from a variable resistor, so give me instructions on which direction you want me to turn the tps and what to look for on the wideband. Fully hot engine, of course.

 

********4) when the TPS is lost, the ECU reverts to a stored setting of 100% throttle (18 degrees, I believe). If the AFM were totally responsible for scheduling, why would the ECU need a specific throttle setting signal?**********************

To know when to turn the Relief and Switching solenoid on/off????????

 

Lol, are you using humor again? You'll need to reread my passage and note that my theory is that the TPS signal is used WITH the AFM's signal, not in lieu of it. I'm not stating that the TPS is responsible for fuel scheduling, in other words, but that the ECU uses AFM along with TPS (and other sensors) to schedule fuel. If it were only the AFM input responsible, why the need for a map???

Turn it clockwise......Now THAT'S humor

 

Turn it clockwise......Now THAT'S humor

No. Turn it in the direction required to get an output of approx one volt , at idle (fully hot engnie,please). Now that's serious talk!

 

Well, what started all of this was my car not idling worth a ****. I think my TPS is toast, but I digress.
At fully tightened down the car runs so pig rich that you can smell the excess fuel, so much in fact that it led me to constantly checking my PD for leaks. At fully loosened, the car runs alot leaner... fuel stench is gone, and the butt dyno says that it pulls harder. I have an RP A/F gauge using the stock O2, and it shows red at WOT with the TPS cranked down, and in the green/yellow now that it's fully loosened.

 

On a series four, the tps is fully extended after approx 18degrees of throttle opening (showing its maximum voltage output). So at wide open throttle it would make no difference how much you cranked it down at idle.

A properly set tps will output one volt at idle to pin 2G of the ECU, with a fully heated up engine. See the free factory service manual. Look in the Fuel Section. Under Control Unit