Another high idle .........

RocketmanBristol

Supercharged
Joined
Jul 23, 2017
Messages
427
Ride
2004 Rocket 3
Hi Guys

Trawling through the old threads trying to find an answer and getting more confused as to what may be wrong!
Cleaned and lubed the springs on the throttle bodies , checked throttle cable slack, cleaned the stepper motor, done all the resets and checked the TPS voltages with Tune ECU, all within spec, reset adaptions and done the 12 minute tune.
Bike runs beautifully on the ride out then as soon as I return to her for the journey home the high idle just makes the ride a real pain, I hate not having any engine braking and as for ridding in the wet would be a nightmare!
Do I need to bite the bullet and buy a new TPS ? The secondarys are removed, can I swap that for the primary?
Thanks in advance.
 
DO not screw with the 2nd tps especially with butterflies removed. although it looks the same it is very different. have u tried (not running) opening the throttle wide and letting it go so it will pop back a few times.
 
warp9.9 said:
Yes I would say a new Primary TPS will solve your issue
Click to expand...

I hate to disagree (with one of the most respected techs on this forum!) .........
but the "fuel" that controls engine speed is Air, not gas
TPS has no control over the volume of air supplied, only the amount of gas that it delivers.
Therefor if the engine speed is high, it's because its getting too much air, not too much (or little) gas.

The most likely cause for high idle speed is an air leak - check the condition of the hoses for the MAP sensor and also to the Emissions canister if your bike has one.

p.s. I see you have a 2004 - that makes your hoses all 13 years old if they have never been replaced!

p.p.s. Take a look at your TuneECU Tests page and compare the MAP pressures for the three cylinders - that might give some hint as to whether you have a leak and where it is. But I would certainly start with a good visual inspection and look for perished spots and cracks in the hoses.
 
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No problem you could be right although a air leak would be there from the get go not after jes road a bit. Where the older original bad tps can give a false reading having the stepper motor move in more for the idle opening the throttle bodies allowing more air. If its at high idle and you shut it off and refire her up and she idles right I would have a hard time thinking the air leak vomes and goes with the cycling of the key. I do agree with changing hoses and plug caps do to age
 
warp9.9 said:
If its at high idle and you shut it off and refire her up and she idles right I would have a hard time thinking the air leak vomes and goes with the cycling of the key.
Click to expand...

Yea, that's how I figured out mine was a TPS problem
 
Did this start after riding in the rain or spraying down the bike? With the tank up, start the bike and fidget with all the accessible connectors and tubes.
 
warp9.9 said:
...Where the older original bad tps can give a false reading having the stepper motor move in more for the idle opening the throttle bodies allowing more air....
Click to expand...

I don't think it works like that
The Idle Control Stepper responds to the engine rpm, not to the TPS - so if the idle is high, the stepper would be attempting to CLOSE the throttles, not open them ... yes?
The TPS might be higher if indeed the throttles WERE open further, but this would have to be courtesy of a sticking cable (or throttle control) vs being commanded to open via the stepper
Even if TPS inadvertently high (erroneous reading) - so what? The idle control should not be responding anyway - if still in idle control mode, it would be telling stepper to close; if outside that zone, then is just not going to adjust stepper anyway .
And again, would be trying to clamp it down, not open it up
It's the cart & horse thing ....... what came first - throttles position, TPS value or engine speed?

The one thing the ECU can NOT accommodate for is an inadvertent air flow - there is nothing it can do to control that.

Another simple test from TuneECU is to just look at what TPS value (look at the Voltage value) when the idle rpm is high - what does it read?
 

Had the high idle problem on my 06 classic a couple years back. Pulled the rear TPS, put it on my bench. It’s a simple potentiometer. Read the resistance sweep with an ohm meter, it was rough. Sprayed some WD 40 into the pot, cycled it a few times with a small flat blade, readings cleaned right up.
Re installed, adjusted position for best idle, been running fine ever since. I think it picks up grime from exposure.
Sometimes it pays to not think so hard on a fairly simple issue... choose your poison.
 


I love this forum many varied opinions no wonder I'm confused lol. Thanks for all the input , have to agree on the air leak as surely that would be present from the start up ,not just when ridden and hot? Will take the TPS off and clean as suggested in the last post, has to be worth a try..............
 
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