I’ve been suffering with a little glitch for a while that I need to go ahead and understand and address. I’ve tried several times to adjust my TPS, but I only ever get 1 light. The second circuit never registers more than about 400 mV, which isn’t enough to light up a bulb, and I’m wondering where the problem is. I’ve adjusted the TPS using an Air/Fuel meter such that the ECU shuts off the injectors when the throttle is completely closed, but the cycles the injectors back on if you touch the throttle just the slightest bit. I’ve also taken care to get it as close to this cutoff threshold on decel, without making it surge during warmup.

The odd thing is that when I give it maybe 0.1% throttle, it bogs (I think I’m 1/8 of a turn from eliminating the bog on the TPS), falling completely off the range of the Air/Fuel Meter, and at 0.2% it sounds like it’s running on one rotor, with a very odd tone, but the Meter shows full rich, like when I’m at full throttle. Anywhere from 10% to 50% throttle and it runs closed-loop like it should, and it cycles between rich and lean like normal.

I’ve never KNOWN that my TPS is right because I’ve never gotten the second light during adjustment, and I have this weird bog and rich condition JUST off throttle, which is the spot I’m fine-tuning with the TPS adjustment. What I’d really like to know is how the lights relate to the low-throttle operation of the car.

I’m wondering if the lights are an output of one of the solenoid valves, in which case no light means no solenoid, and that explains why my transition might be so choppy. If having no light means that I’m not ever triggering a solenoid or relay, then I’ve got a different problem altogether.



Does anyone understand the GSL-SE well enough to know what only one light really means (not covered in the FSM, so far as I know) and whether or not it would contribute to my choppy throttle?

 

Unplug the TPS and measure resistance between each 'eye' and the 'mouth'. One set should start off at like 5kOhm and decrease as you push in the plunger. The other should start at like 1k and increase as you push in. If this is not the case, the TPS itself is bad. Make sure that you push the plunger slowly and look for dead spots (resistance jumps out of range) or any other funny behavior.

When you set the TPS, this is what happens:
- the TPS gives two resistance values (voltage really) to the ECU
- the ECU interprets this..plus other things..and outputs a signal to the vent/vac solenids. These control the BAC which in turn controls the idle.

The TPS set connector is actually connected to the vent/vac solenoids (at output from ECU). So 1 light means that only one of these solenoids is active (vacuum solenoid will be the active one when things are set correctly).

Now the vent/vac solenoids should really cuase this bog on their own (unless maybe the BAC is open at idle and then slams shut at part throttle). Seems more like the TPS itself.

The fact that you are not able to get two lights suggests to me that the TPS itself may be bad (do the resistance test). It could also be the ECU or wiring/connectors from the TPS to the ECU as well. For whatever reason, the ECU is not correctly interpreting the TPS...

 

Do you normally have any shudder when transitioning from off-throttle? Is it imperceptible to passengers but you always notice?

 

hi , so if i'am reading this right . you must have 2 light on when you adjust the tps.

 

no..you want only one to come on. The problem is that he can't get two lights to come on no matter how much he tries..should be like this:

screw turned one way too far = no lights
screw turned the other way too far = both lights
set correctly = one light

 

okay , thank you

 

Funny you mention the one-rotor running thing......

Thats something that I hear A LOT, on all kinds of EFI rotaries.
My S4 engine did it,my S5 engine does it,my brothers S4 non-turbo did its,and there is even a very loud FD that cruises by my work every day,and it stutters on one rotors as he coasts/cruises around the bend near my shop.
I dont know if its a function of the EFI to cut in one rotor as a time when you tip into the throttle,maybe to smooth things out? It seems to do that regardless of TPS condition,engine temp,state of tune,or even fuel injection type (metered on S3-S4-S5 or speed density on the S6).I can get in my car at any time and MAKE it run on one rotor while cruising simply by resting my foot on the throttle the tiniest amount. Any more or any less, and the injectors come online or cutt-out,respectively.