Throttle Position Sensor

[raz]

I guess this thread should be un-pinned as the resulting How-To is pinned in the FAQ section. Some people has ended up reading these literally hundreds of posts instead of finding that one!

[docc]

I guess this thread should be un-pinned as the resulting How-To is pinned in the FAQ section. Some people has ended up reading these literally hundreds of posts instead of finding that one!

Agreed!

[thebronze]

Ok i'm diving into this and have found some strange results.

1. With the throttle rod disco'd, iggy on, motor off, the top sensor wire reads 0, the bottom reads 447.

2. There isnt a right idle screw, but there is a left idle screw that pushes into the throttle rod.

 

According to the FAQ it says the difference should be 150. I'm looking at 440. Taking a break to find another vacuum gauge.

[docc]

The 150 mV is for completely closed throttle with the rod disconnected, no stop screw contact, no fast idle cam contact. Your reading looks like there must be some contact. The right idle screw is on the inboard side of the back of the throttle body (vary hard to see/ adjust and one more reason to back it fully out); The fast idle cam and cable are under the front of the right throttle body and will also interfere with the 150 mV closed throttle plate setting.

 

Not entirely sure what you mean by top and bottom wires as the voltage is read between them in millivolts DC.

 

Pinned thread in FAQ for reference: TPS Setup and Throttle Balance Tuning

[thebronze]

The 150 mV is for completely closed throttle with the rod disconnected, no stop screw contact, no fast idle cam contact. Your reading looks like there must be some contact. The right idle screw is on the inboard side of the back of the throttle body (vary hard to see/ adjust and one more reason to back it fully out); The fast idle cam and cable are under the front of the right throttle body and will also interfere with the 150 mV closed throttle plate setting.

 

Not entirely sure what you mean by top and bottom wires as the voltage is read between them in millivolts DC.

 

Pinned thread in FAQ for reference: TPS Setup and Throttle Balance Tuning

 

Thanks Docc, i'm using the other thread as a guide. I'm a bit confused on reading the tps leads. How do you read the mv between the two leads? I have two wires stuck into the connector and read them one at a time. Am I meant to read them both at the same time? I have alligator clamps on my multimeter leads to get the reading. Also, by fast idle do you mean the choke cam that goes up to the h bar thumb adjuster? I'll have another go in the morning. I did find that the left air screw was all the way in and the right was 1.5 out.

[thebronze]

I figured it out Doc, thank you very much. The right idle screw is really hard to find. I removed the k&n filter and the boot and there it was all gunked up w yellow paint. I guess guzzi put that paint in there to keep us from fiddling around...

 

(edit) Running into a few issues:

 

Cant seem to get 520 without the idle going too high. If I turn in the L idle screw to raise the tps reading to 520 the idle goes up to around 1800rpm. Bleed screws at 1/2 turn out. Full turn out doesnt seem to make a difference.

 

Bike runs worse now, i'm wondering if these crappy vacuum gauges need to be replaced.

[docc]

That's a huge disparity in air screws. Makes me think something else has been amiss. Be certain to adjust the valves to a proper spec "stone cold." Fit fresh plugs and synch the throttle bodies.

 

Dave Richardson once noted this same phenomenon in Guzziology: when you tweak the idle it changes the TPS, when you tweak the TPS it changes the idle. But they keep converging as you work so don't give up. Also, realize your tach my read high, so trying to tune at an indicated 1100 could be expecting the motor to be happy at 750 or 800 rpm (it won't be).

 

Yes, the hi-idle cam is the "choke" gizmo. Voltage is read between the positive (black/purple) and the negative (purple).

[thebronze]

That's a huge disparity in air screws. Makes me think something else has been amiss. Be certain to adjust the valves to a proper spec "stone cold." Fit fresh plugs and synch the throttle bodies.

 

Dave Richardson once noted this same phenomenon in Guzziology: when you tweak the idle it changes the TPS, when you tweak the TPS it changes the idle. But they keep converging as you work so don't give up. Also, realize your tach my read high, so trying to tune at an indicated 1100 could be expecting the motor to be happy at 750 or 800 rpm (it won't be).

 

Yes, the hi-idle cam is the "choke" gizmo. Voltage is read between the positive (black/purple) and the negative (purple).

 

TB's are now synched, seemed like about 17 on the mercury sticks. TPS is at 520 at idle. Bleed screws 1/2 out. Idle around 1400. Ran great until it got hot, then started snick snick hiccups and wanting to die at stop signs. I'll check the valve lash and report back. Seems like the hotter the bike gets the worse it runs.

 

Does the engine temp sensor lean out the mixture when the engine gets hot?

 

Thanks again Docc, you are a huge help.

[docc]

Nasty Hiccups in hot ambient temps have been a common aggravation.

 

Various known attempts at improvement include: removing the air intake snorkels, opening the air bleed screws to a full turn, loosening the valve lash, increasing the idle speed, securing the 30 amp regulator fuse, securing all of the relays and connections (including regulator grounding), modifying the Engine Temperature Sensor.

 

It only gets better!

[gstallons]

That's a huge disparity in air screws. Makes me think something else has been amiss. Be certain to adjust the valves to a proper spec "stone cold." Fit fresh plugs and synch the throttle bodies.

 

Dave Richardson once noted this same phenomenon in Guzziology: when you tweak the idle it changes the TPS, when you tweak the TPS it changes the idle. But they keep converging as you work so don't give up. Also, realize your tach my read high, so trying to tune at an indicated 1100 could be expecting the motor to be happy at 750 or 800 rpm (it won't be).

 

Yes, the hi-idle cam is the "choke" gizmo. Voltage is read between the positive (black/purple) and the negative (purple).

 

TB's are now synched, seemed like about 17 on the mercury sticks. TPS is at 520 at idle. Bleed screws 1/2 out. Idle around 1400. Ran great until it got hot, then started snick snick hiccups and wanting to die at stop signs. I'll check the valve lash and report back. Seems like the hotter the bike gets the worse it runs.

 

Does the engine temp sensor lean out the mixture when the engine gets hot?

 

Thanks again Docc, you are a huge help.

Are you running a stock ECU or PowerCommander ?

[thebronze]

Are you running a stock ECU or PowerCommander ?

 

Stock ECU, K&N air filters, the air sensor has been relocated to a small platform near the seat area. Not near the engine. I think I need someone with the vdst software to take a look inside and cut out the guesswork. My local mechanic has 02 analyzer and other goodies but he's expensive and I dont want to give up just yet!

[docc]

The VDST would be good to confirm your CO is zeroed. My Sport was delivered at MINUS 27. Also, good to confirm your tachometer error to insure idle accuracy (my Veglia reads 300 rpm high and I've heard 500 is not uncommon).

 

Everything else, you can do with your tools and taking the time. I'm not sure it's mentioned in the tuning thread, but setting a strong fan in front of the motor during the tuning process will help keep the engine temps from going too high.

[Tom M]

I agree with Doc that it would be a good idea to check your idle trim with VDST, but if your idle is at 1400rpm and your tps is at 520mV I would expect your mixture would be lean even if idle trim is zero. IMO you should turn your idle down to 1050-1100rpm then reset your TPS to 530mV.

 

I've had good luck with a simplified version of the V11 tuneup known as the "Micha Method":

 

Step one - Set your valves to world settings (.15mm/.006" intake, .2mm/.008" exhaust)

Step two - Set your air bleed screws to open 1 full turn

Step three - Synch throttle bodies at just off idle (around 1800 rpm)

Step four - Set idle to 1100 using left idle screw adjuster only

Step five - Set TPS to 3.6 degrees (530mV)

Step six - Ensure idle trim is set to zero. This requires an AXEONE dealer tool or VDST software.

[thebronze]

I agree with Doc that it would be a good idea to check your idle trim with VDST, but if your idle is at 1400rpm and your tps is at 520mV I would expect your mixture would be lean even if idle trim is zero. IMO you should turn your idle down to 1050-1100rpm then reset your TPS to 530mV.

 

I've had good luck with a simplified version of the V11 tuneup known as the "Micha Method":

 

Step one - Set your valves to world settings (.15mm/.006" intake, .2mm/.008" exhaust)

Step two - Set your air bleed screws to open 1 full turn

Step three - Synch throttle bodies at just off idle (around 1800 rpm)

Step four - Set idle to 1100 using left idle screw adjuster only

Step five - Set TPS to 3.6 degrees (530mV)

Step six - Ensure idle trim is set to zero. This requires an AXEONE dealer tool or VDST software.

 

Tom, why 530? The main thread says 520. Would my K&N's be leaning out the air mixture? Does the TPS reading equate to a fuel mixture, where 530 would be a bit richer?

[thebronze]

I called my local mechanic who works on Ducatis. Turns out he worked at the local Guzzi dealership in 2002 when my bike came out. He said Guzzi had a problem with the fuel maps back then and most the bikes were lean in the midrange. Said it would buck between 3-4k just like mine. He was fixing them by adjusting the tps setting to enrichen the midrange. I'm guessing my k&n pod filters arent helping a lean mix. I made an appointment to take the bike in but i'll try the 530mv before giving up.