Question TRYING to solve the snatchy throttle

[Piggy]

So I’ve been giving some thought to the throttle response issues that some experience. From what I gather, the real complaint is a delayed response off idle. I don’t hear that the problem exists from part-throttle roll-ons. Further, the issue doesn’t necessarily present itself while the bike is in neutral. This suggests that the ECU is using either speed related data or gear position to change from a “neutral” map to an “in-motion” map.

There are two parts of the EFI system; The Fuel Delivery System and the Control System. Hear are the parts that make up each:

Fuel Delivery System

• Fuel pump
• Pressure regulator
• Fuel injector
• Throttle body

Control System

• Engine Control Unit
• Throttle position sensor
• Intake air pressure sensor
• Coolant temperature sensor
• Crankshaft position sensor
• Intake air temperature sensor

Does anyone notice what is missing from these lists? Speed or gear-position data.


For those of you that have this problem, can you conduct some tests for me?

Test 1. Confirm/Disprove that the delayed throttle exists in neutral.

Test 2. While in motion and the problem is present, determine if the delay is a result of throttle position, or time.

Test 3. Confirm/Disprove that the delayed throttle exists only from an idle position, not a part throttle roll-on.

Test 4. Confirm/Disprove with the bike in motion, but in neutral, that the delayed throttle exists

Test 5. Confirm/Disprove with the bike in motion, in gear but with the clutch engaged, that the delayed throttle exists

Test 6. Confirm/Disprove that the throttle delay issue is NOT present in 6th gear. (added from post #71).


Depending on your inputs we can determine what ADDITIONAL input the ECU reads besides the noted Control System inputs. This problem could be as simple as a speed sensor or a faulty neutral/gear position switch. If one of the above sensors has a fault, it registers a fault code, however if other data is being used no fault codes exist for the failure.

I will try and do this 6 test list later this week if I can

 

[Morelius]

good day everyone! Wow I totally missed all these replies since my last.. .been a long winter with suspension upgrades and I've ridden the bike only twice since going to DynoJet HQ in UK and getting an on the dyno tune. The bike rips and has more power all over the range but that issue is still present.

It is well described by a few of you here... the throttle goes from 0-5% in one step if you like...

Things I have done;

AIS delete.
Perfect throttle cable adjustment.
TPS adjustment (and replacement)
New chain and sprockets and cush drive. Chain tension changes make no difference.
Balanced the throttle bodies
Tested fuel pressure
...the list goes on.

It is the "dreaded Yamaha fuel cut" issue as descibed and if I cannot find a solution this year (despite throwing a grand at the bikes suspension upgrades)... I will be looking to get a different bike next year

One chap here described well how scary it is in 2nd and 3rd when leaning over and it hits hard despite focusing on smooth throttle input. Once throttle open... say holding at 20%, then gently opening it and its not there...

Its from 0% to throttle open... injection delay.

The resistors solution above I am very curious about but I'd like to know what it actually does... what is it tricking the ecu into thinking??

Tricks the ecu to think there is still suction or slight pressure in the airbox and therefore it does not cut fuel. There is a lot of info if you want. Just google "zady5". It works. I was very close to sell the bike til I tried it.

I did the 6 test. Worth nothing. You should go straight to the mod.

 

[Piggy]

Tricks the ecu to think there is still suction or slight pressure in the airbox and therefore it does not cut fuel. There is a lot of info if you want. Just google "zady5". It works. I was very close to sell the bike til I tried it.

I did the 6 test. Worth nothing. You should go straight to the mod.

So the ECU cuts fuel when it sees vac at the manifold but 0% tps and idle switch not engaged?...

zady5 the original thread on the FZ1 forum really explains all this... wish I had found it sooner... he describes perfectly what i could "see" in my head the ecu was doing and it explains why a PC/dynojet remap will not solve it as the ECU is using the map sensor for fuel on/off cut below 18% on the fz1.. .I cant imagine they changed that much for the fz6

 

[Morelius]

So the ECU cuts fuel when it sees vac at the manifold but 0% tps and idle switch not engaged?...

zady5 the original thread on the FZ1 forum really explains all this... wish I had found it sooner... he describes perfectly what i could "see" in my head the ecu was doing and it explains why a PC/dynojet remap will not solve it as the ECU is using the map sensor for fuel on/off cut below 18% on the fz1.. .I cant imagine they changed that much for the fz6

Try it... You have nothing to lose

 

[Lukenzo]

good day everyone! Wow I totally missed all these replies since my last.. .been a long winter with suspension upgrades and I've ridden the bike only twice since going to DynoJet HQ in UK and getting an on the dyno tune. The bike rips and has more power all over the range but that issue is still present.

It is well described by a few of you here... the throttle goes from 0-5% in one step if you like...

Things I have done;

AIS delete.
Perfect throttle cable adjustment.
TPS adjustment (and replacement)
New chain and sprockets and cush drive. Chain tension changes make no difference.
Balanced the throttle bodies
Tested fuel pressure
...the list goes on.

It is the "dreaded Yamaha fuel cut" issue as descibed and if I cannot find a solution this year (despite throwing a grand at the bikes suspension upgrades)... I will be looking to get a different bike next year

One chap here described well how scary it is in 2nd and 3rd when leaning over and it hits hard despite focusing on smooth throttle input. Once throttle open... say holding at 20%, then gently opening it and its not there...

Its from 0% to throttle open... injection delay.

The resistors solution above I am very curious about but I'd like to know what it actually does... what is it tricking the ecu into thinking??

It raises lower side of MAP signal a bit so ecu sees air being drawn (or rather doesn't see rapid throttle close) in and doesn't shut down fuel all the way down (keeps injectors open for longer) after you close a throttle, it's like a buffer between accel and decel maps. Fuel cut still happens but it's in lower rpm's and does not bother me much. I noticed some weird fueling on cold engine (too rich) and it probably does change a/f ratio out of spec in some rpm's even on hot engine, but as long as it's on rich side and below like 6K rpm it should be fine.