I haven't seen this mentioned before so here goes - this could be a neat trick in a jam. This works on my S4 NA at least.

I've noticed when adjusting the TPS with two lights, that when each one turns on, a faint sound is heart from the solenoids at the ACV. So in a bind, you can maybe turn the screw out a couple of turns (if you know you're close) and then listen for one, then two clicks, and then back off until one unclicks.

I know this isn't the best explanation - you have to try it out with test lights hooked up first so you know when the solenoids should click and what to listen for - it's very faint.

Anyone else notice this?

 

No. It's not the ACV making the clicking. It's the Switching and Relief solenoids clicking.

Look at the wiring diagram. Two of the wires in the TPS check connector are tee'd off to the plugs to those solenoids. When set properly the ECU sends a gnd signal to the Relief solenoid to energize it and removes a gnd from the switching solenoid to de-energize it.

 

And why does it do this?

 

It does this because when the tps output is approx one volt, the ECU outputs a gnd signal to the Relief solenoid and removes it from the Switching solenoid.

It does that so there will be a vacuum on the relief diaphram inside the ACV and the Switching diaphram inside the ACV at idle (the two solenoids work *** backwards from each other as to when the path of vacuum passes thru them when energized/de-energized.

So I guess it MIGHT be possible that PFSANTOS could actually hear the diaphrams inside the ACV moving. Seems more likely he heard the solenoids though.

Anyway, the same gnd output by the ECU to the solenoids is also outputed to two of the wires in the tps connector. That's why the lights come and go on the led's at the tps connector. See the wiring diagram of the tps connector in the FSM and how the wires are also connected to the two solenoids.

This stuff has been mentioned in the past on this forum. About once or twice a year.

 

Yes, most of this has been mentioned in the past, but not the part about not needing a test light though...and I searched.

Sure, it's easy to rig up a test light and have one in the car, but if stuck without one, this confirms one doesn't really need it - in a bind. I once totally screwed up my TPS adjustment, opened the throttle all the way and pushed the TPS plunger in until I heard some clicking. This got me pretty close so that I could move on to finer adjustment.

 

The clicking sound you're hearing is from the LEDs themselves turning off and on. It was a good suggestion, but unfortunately one must have the light setup in order to hear the clicks.

 

LED's don't CLICK.

Like I said, it's the Switching and Relief solenoids clicking. Read and understand the FSM.

 

Oh my word!

 

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So I'm curious, if the TPS was a bit off, could it cause the Check Engine light to come on and flash a code telling me that the switching solenoid is bad? Even though I've tested it as per the FSM and its good?

 

More likely one of the two wires to the switching solenoid plug is disconnected/cut/whatever.

Codes really suck imho. They mostly mean that whatever unit is kicking the code, has its connector disconnected or has a intermittent open on one of the wires to it..

 

What if...
...you have no ACV, solenoids, nothing?


-Ted

 

HAHAHA!..IF LED'S CLICKED:then all the Cars with Underglow would be Zipping by Making the Sound of a Drummer on Crack!..God-Dammit!,..Come on! Your "knowledge of Electrical Wizardry",Makes me Laugh!..let me know your Paypal..I will send you a Dollar to Stay in School!

 

You should kick a code for each item removed. Never tried it myself. Just own series four and no series five who's list of codes is a touch longer than series four.

If I pull the plug off the engine intake temp sensor I kick a code. PUt it back on and code goes south.

 

Quick TPS check (while driving)
This works best with a loud exhaust. Find a flat open road with no traffic. Cruise along at about 3K rpm in 3rd or 4th. Lift off the throttle. This should give a fuel cut on both rotors as you back down. The motor is just pumping air. Very gently pick up just the slightest throttle. With practice you can hear the rough sound of only #1 rotor getting fuel, while #2 pumps air. Then adding just a little more throttle, #2 comes on.
You can also do this as you slow down in gear and the throttle is very near, but not quite at idle.
As you lift the throttle you can hear the #2 fuel cut before #1.
When you get down to near 1500rpm fuel comes back on to prevent stalling, so this works best around 2-3k.

 

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Sureshot - you might have a very good ear, but where'd you get this info? I didn't see this in the FSM (S4) in the part about fuel-cut. Is this an S5 thing? Please quote the page number if you have it.

 

I have not seen it in the FSM, but it's fairly typical of fuel injection systems, so I just listened for it.
Sure enough the coast down fuel cut happens in stages right near closed throttle for both S4's & S5's.

 

Put an AFR gauge to monitor the exhaust.
You'll see that it's supposed to dead lean as soon as your lift off.

You can also monitor the fuel injectors if you got an "IPM" - injector pulsewidth monitor.

This is not an S4 or an S5 thing.
It's a FUEL INJECTION thing.
Almost every car with electronic fuel injection will do this.


-Ted

 

...the fuel-cut of the injectors I knew from the FSM, but that it happened in stages is totally new to me...

Always learning something new here!

 

FUEL SECTION, SERIES FIVE, page called OUTPUT DEVICES............................both primary injectors cut off during deceleration. Same on a series four. Cut off at the same time during deceleration.

OUTPUT DEVICES in the series five FSM is a chart looking outfit. Most of which also applies to series four. Most, not all.

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