Climbing and dropping idle mystery

[JBBenson]

Idle mystery for the peanut gallery:

 

Specs:

2000 V11 Red Frame

Stucchi x-pipe

Mistral canisters w/ db-killers

Guzzitech map, .475 v at TPS idle setting.

Balanced throttles, using LH idle screw only, no interference in the throttles or connecting rod

Relays have been mounted on a strip of aluminum to secure them

Air bleed at 1.75 left and right

Valves @ .006" intake and .008" exhaust

New air filter, fuel filter, new regulator ground to engine

5000 miles

 

Note: All RPM’s are indicated, maybe not actual

 

On cold start, idle will settle in at around 1700

When the bike is warned up, idle will drop to about 1200, which feels ideal for me.

 

Sometimes, after a hard mountain run, idle will settle at 1000. After some traffic stops, idle will settle between 1200-1500. Then after another couple of stops, idle will drop again to 1000, or slightly less. Recently dropped so low at a stoplight the engine died.

 

Throttle cable is free, return spring snaps closed just fine. Intake rubbers are either new or in good shape. I tightened all the clamps on the intakes as well as the exhaust pipes. There is no popping or banging in the exhaust. I have changed the air bleed a few times, up and down, and although that changes the idle, it doesn't stop the up and down idle issue.

 

Bike runs and drives otherwise really well, I am very happy with it. Finally.

 

I can only think of a couple of things:

 

1.

Valves are not where I think they are, i.e. too tight, and the warm engine closes them up a bit and drops the idle. But that doesn’t explain the return to high idle after some stops and starts.

 

2.

Intake rubbers are leaking even if I think they are not. Explains the climbing idle but not the dropping.

 

3.

Crud build-up on the TPS that doesn’t let the butterfly close consistently every time. At 5000 miles? The bike is pristine.

 

4.

Could be the fuel additive I have been using lately, Bell Performance Ethanol Defense.

 

5.

EFI Moto Guzzis “just do that”, especially in hot weather (about 90F where I am), especially in stop and go traffic. Stop complaining.

 

What say you?

[Trevini]

I suspect it's a temp/mixture related issue.  As soon as you get in stop/start traffic they get hot quite quickly, having the effect of running richer.  It's probably that that is causing the revs to drop a bit if it's a touch rich to start with.  If it were running lean, you'd probably find the revs increased a little.  Bearing in mind the efi system is quite ancient now and doesn't run closed loop like newer systems and is therefore, effectively just an electronic carb rather than a fully managed injection system. 

 

If it's any consolation, mine drops a bit when it gets really hot in traffic, but soon settles back to "normal" when it's been ridden at proper speeds again.  I did go down the route of using just the left screw, but found it to be more stable using both screws.  I did wonder if having the right screw backed off allowed a little movement on the right hand throttle body (any slack in the linkage) as the engine pulsed.

[Kiwi_Roy]

I find with mine there is too much slop in the throttle linkage for the one stop method, I tried, it gave ma a different revs each time

 

Now I use both

 

A quick and dirty way from here is just wind in the right hand stop until it makes contact with the throttle, now it will always come back to the same spot

[thebronze]

My 02 has the exact same problem.  Every summer when its hot, it will die at stop lights no matter how high the idle is set.  This has been happening for 2 years and i'm very close to selling the damn thing.  No amount of TPS or TB synching will fix it.  Its been in and out of the shop several times.

[docc]

475 mV seems pretty low for the TPS idle setting. Have you established the 150 mV baseline with the throttle plate completely closed?

 

If so, your best idle is more likely found about 525 and air screws at one turn (+/-).  The air screws can get really sooted up, so you might want to pull them out and clean them along with the holes they fit into.

 

Otherwise, we might, once again, launch into discussing the head temperature sensor holder . . .

[JBBenson]

475 mV seems pretty low for the TPS idle setting. Have you established the 150 mV baseline with the throttle plate completely closed?

 

If so, your best idle is more likely found about 525 and air screws at one turn (+/-).  The air screws can get really sooted up, so you might want to pull them out and clean them along with the holes they fit into.

 

Otherwise, we might, once again, launch into discussing the head temperature sensor holder . . .

Yes, I disconnected the throttle connecting rod, set TPS at exactly .150 v (using a breakout harness), reconnected the rod, and adjusted the LH throttle stop screw until I reached a TPS reading of .475 v (per Todd @ Guzzitech....I am using his map). 1 turn out on each air bleed and she idled perfectly in my garage.

 

That doesn't mean you aren't right, and the millivoltage @ idle couldn't be a bit higher. I have not tried this yet, as the bike runs really really well otherwise. 

 

The air screws seem to affect only the idle speed in general, and fiddling with them, (which I have), doesn't seem to stop the up-and-down quality of my idle. It seems to be more of a temperature thing more than anything else. I think Trevini is on to something, the throttle feels "boggy" when hot, like it is running too rich,

 

I suspect the head temperature sensor might be giving weird readings to the ECU when it (and the motor) is hot.

 

The bike does seem too run a little hot, and my knees get pretty warm. But, admittedly, it's hard to tell when the ambient temperature is hovering around 90 Fahrenheit....everything is pretty hot.

[luhbo]

... I think Trevini is on to something, the throttle feels "boggy" when hot, like it is running too rich,...

 

The picture (one of dlaing's) shows that the mixture gets leaned out at higer temperatures. On hot days I've seen head temperatures up to 100°C and above (at stop lights, in city traffic), while onroad on colder days sometimes the temperature hardly rises over 55°C.

Before you start tinkering with these values you should doublecheck that the basic tuning of your bike is correct.

 

Hubert

[docc]

When setting your base value TPS, you did not mention releasing the high idle cam. With the throttle rod disconnected, the plate closure can still be affected by the high idle cam as well as still hitting the right idle screw, even if that was already backed out enough as not to affect the idle itself.

[JBBenson]

Docc: I did clear the high idle cam when setting it up. 

 

Checked the TPS and turned out it had drifted to .462 v, which doesn’t sound like a lot, but not the .475 v that I set it at a while ago.

 

Per Docc I bumped it up to .500 v and reset air bleeds to .075 turns out.

 

Took a ride, and the idle is for sure more solid, never varying more than +/- 100 RPM, mountain twisties or stop-and-go traffic.

 

It tended to settle around 1400 (indicated), which is a little high, but since I upped the TPS 38 millivolts not really surprising. Might need to bring it back down just a tad.

 

Lesson is: the throttles/TPS drift a bit, and having the breakout harness from Casper’s made it really easy to diagnose and adjust. Took 30 seconds. Get one...!

 

Still amazed that a sump motor like the V11 is so sensitive to tiny adjustments.

[docc]

Down to the "fine tuning" now!

 

Being certain of fresh plugs and spot on valve adjustment, set your throttle body balance at some rpm (maybe 2500) and lock the white knob with a nut (per Dave Richardson/ Guzziology), then at idle balance the final balance with the air bleeds.

 

As the air bleeds change the idle, and the idle changes the TPS setting, and the idle screw starts this all over again, the settings get closer and closer (better and better) at each session.

[czakky]

JB, I've always had a similar issue as what you describe. I'm sure that you in South Cal. me in FL our ambient temps. are similar. I had just recently set my CO trim up to 3 using Guzzidiag and it really seems to help. FWIW

[mznyc]

Fuel settings,CO,or an air leak.Also headers are know to leak.Cracked TB boots gave me your symptoms,but air leaks anywhere else would have the same effect.

[JBBenson]

UPDATE:

 

Well, while waiting for my forks to be rebuilt by Todd @ Guzzitech, I decided to replace all vacuum hoses and intake rubbers to eliminate the possibility of air leaks. I also replaced the plastic head sensor with the brass one. Then I reset everything: disconnect cold start cam and connecting rod, set TPS voltage to 150mV fully closed, etc etc etc.

 

Forks came back, and I took it for a test ride. Front end is WAY better, the new Raceco valving and springs have transformed the crappy Marzocchis the bike came with, but the damn idle is still up and down,  WTF?

 

I tightened all the clamps, unhooked the throttle connecting rod, and attempted to reset the TPS again at 150mV. This time, I noticed that every time it snap closed, it gave me a different reading on my multimeter: 145mV, then 152mV, then 156mV, then 148mV, etc. It also felt a little sticky. I hooked up the connecting rod and noticed the same thing: I never really got a consistent reading when the throttle was shut.

 

This would explain a lot. When the throttle snaps shut, something is blocking it, it feels sticky, so it never really reaches the same exact angle. We are talking about tiny fractions of volts, but there they are.

 

I removed the rear intake rubbers and saw that there was a lot of build-up of gummy old gas on the throttle plate (esp. the edges and pivots) and the throttle body walls. I got to cleaning using carb cleaner and q-tips, pouring in the cleaner and letting it drain out until it was almost clear. I also cleaned all of the exterior springs, levers, pivot points etc. Also pulled the air bleed screws and really cleaned them and the port they screw into.

 

Then I reset the baseline TPS at 150mV, connected the rod, set the TPS to 520mV, opened the air bleeds to 1 turn out, and put my helmet and jacket on.

 

Just for good measure, I dumped some Seafoam into the tank and went for a ride, giving it an Italian Tune-Up when the motor was warmed up.

 

The idle is now pretty solid at an indicated 1600 RPM, so I am guessing a real idle RPM of around 1200-1300.

 

Problem seems solved. When I am up to it, I will pull the throttles and soak them in cleaner. 

 

But for right now, I want to enjoy the “new bike feel” I have with the new front end…..!

[fotoguzzi]

you don't say the mileage but could the butterfly pin be loose (worn) in the holder so it can wiggle around and not be landing in the same closed position each time>?

[JBBenson]

you don't say the mileage but could the butterfly pin be loose (worn) in the holder so it can wiggle around and not be landing in the same closed position each time>?

 

Bike has 5k, so probably not that, but the V11's general sensitivity to TPS angle just reinforces the need to keep everything clean and tidy around the intake.

 

.....also that ethanol gas is really crappy, especially if the bike sits in a hot garage and is only used periodically. Now that it's clean, I will watch to see how fast the crud builds up.