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Discussion Starter #1
Hi guys.

I have a 2001 MV F4 750 that I can't get to run right.
Whatever I do, I can't get it down in CO%. Actually it's usually around 9-10% CO :eek:

Ofcourse that means it won't idle properly and eventually will foul the plugs.

When I got the bike, it had a gear indicator and Powercommander fitted. I removed both in trying to fix the issue.

Furthermore I have fitted the standard EPROM since I know nothing about the one that was fitted.

Cleaned the tank and pump mesh, and fitted a new fuel filter.
New spark plugs.

I have the idle CO turned all the way towards lean. If I turn towards rich it will choke the engine on fuel.

Fuel pressure is about 3 bar all the time.

I have also tried to unplug the Air Temperature Sensor and the water temperature sensor fitted in the cylinder head. Neither has any effect.

TPS and throttle balancing has also been done.

I can start the engine and it will rev pretty decent but blow a lot of black fuel smoke. Appears that the revs wont climp higher than about 11-12.000 rpm.

Any good ideas?
 

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Check specification and service state of air filter.
Plug gaps and type.
Air pressure sensor plays a key role in the ecu determining both the duration and timing of the fuel injection.

Good luck !
Joe
 

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Discussion Starter #3
NGK CR9EB - Stock gap.
Air box not mounted while I do the servicing, but air filter is new BMC.

Where is the air pressure sensor mounted?
 

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Air pressure sensor in LHS air tube level with headstock, easily accessible with fairing off.
 

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Discussion Starter #5
Okay thought that was the Air Temperature Sensor.
I've unplugged it and without any result... Bikes still running insanely rich.
 

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Okay thought that was the Air Temperature Sensor.
I've unplugged it and without any result... Bikes still running insanely rich.

The sensor is dual ie air pressure and air temp.

Interestingly when air temp is low :penguin: the temp thermistor resistance increases.

Then fuel injection duration is increased.

So, pulling the connector plug will cause full electrical open and your fuel injection duration will be at it's greatest ie richest ? :jsm:

So in pulling the connector you aren't isolating the problem, ?



I have a feeling though that the fuel pressure regulator is at fault here ? I read you checked it though :smoking:

Joe
 

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Discussion Starter #7
The readout I get when checking the fuel pressure is a little bit unstable - I think that's mostly due to the fact that my gauge is leaking a little bit.
Anyway it pretty much holds 3-3.5 bar. Not super stable...

Okay I've gotten hold of the diagnostic software now and will see what that tells me (if I can get it to work :))
 

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NGK CR9EB - Stock gap.
Air box not mounted while I do the servicing, but air filter is new BMC.

Where is the air pressure sensor mounted?[/QUOTE

Is the air filter over oiled?
 

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what rpm does it idle @

could be some one has adjusted the link in tb's, i couldnt get my 910 to run right when i first got it, sort of like a splutter @ idle, cleaned filter, changed ecu, tb sync, tps reset and so on could not get it to run, as if it was really rich, turn the main link facing the ecu 2 turns clock wise and see how that is!
 

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Discussion Starter #10
No... And it's not mounted. I don't have the airbox on at the moment - doesn't change a thing if I have it on or not.

I can't get the diagnostic software to work on my laptop so I'm kinda stuck.

Is there a chance that there's a fault in the ECU making it run so rich?
I don't have access to a ECU i can borrow but i'm at the point where I would be willing to buy one and hope that cures the problem.
 

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Discussion Starter #11
what rpm does it idle @

could be some one has adjusted the link in tb's, i couldnt get my 910 to run right when i first got it, sort of like a splutter @ idle, cleaned filter, changed ecu, tb sync, tps reset and so on could not get it to run, as if it was really rich, turn the main link facing the ecu 2 turns clock wise and see how that is!
It's having trouble idling when hot... But it will sort of idle at about 1000 rpm.

I have done TB sync and TPS adjustment. Done as instructed on bikeboy.org.
 

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No... And it's not mounted. I don't have the airbox on at the moment - doesn't change a thing if I have it on or not.

I can't get the diagnostic software to work on my laptop so I'm kinda stuck.

Is there a chance that there's a fault in the ECU making it run so rich?
I don't have access to a ECU i can borrow but i'm at the point where I would be willing to buy one and hope that cures the problem.


Lars,

You haven't checked the sensors from what I can read. Pulling them doesn't give you the definitive answer so you're not really any further forward in your diagnosis .

Check the engine temperature sensor..the one in the cylinder head using a meter and the workshop manual. The one in the rad is for the instrument and not engine management.

As I read, if the temp is low then there should be a higher resistance across the sensor pins and the ecu will adjust for a cold engine both in ignition advance and a richer mixture.

By pulling the sensor connector you are then giving full resistance so the ecu will tell the injectors to spray fuel for a longer duration..ie RICH.

The test procedures are in the manual.

It's interesting to note that an under voltage from the system will also cause a richer mixture. I didn't know that until I just read it in the manual !

If there is an ecu prob talk to Adam


Adam Merc

JOE
 

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Discussion Starter #15
Lars,

You haven't checked the sensors from what I can read. Pulling them doesn't give you the definitive answer so you're not really any further forward in your diagnosis .

Check the engine temperature sensor..the one in the cylinder head using a meter and the workshop manual. The one in the rad is for the instrument and not engine management.

As I read, if the temp is low then there should be a higher resistance across the sensor pins and the ecu will adjust for a cold engine both in ignition advance and a richer mixture.

By pulling the sensor connector you are then giving full resistance so the ecu will tell the injectors to spray fuel for a longer duration..ie RICH.

The test procedures are in the manual.

It's interesting to note that an under voltage from the system will also cause a richer mixture. I didn't know that until I just read it in the manual !

If there is an ecu prob talk to Adam


Adam Merc

JOE
I used the manual now to check the water temp sensor and air pressure/air temp sensor.
Water temp sensor checks out fine.

Air temp sensor shows about 30 k ohm resistance at 20 degrees celsius. It kinda seems like the pin out in the manual doesn't correspond with the bike.
I ordered a sensor using the online parts catalogue so I will wait and see if that helps. It only costed about 45 euros and i'm kinda loosing my patience :)
 

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I used the manual now to check the water temp sensor and air pressure/air temp sensor.
Water temp sensor checks out fine.

Air temp sensor shows about 30 k ohm resistance at 20 degrees celsius. It kinda seems like the pin out in the manual doesn't correspond with the bike.
I ordered a sensor using the online parts catalogue so I will wait and see if that helps. It only costed about 45 euros and i'm kinda loosing my patience :)

Hi Lars..Yes I feel your pain !

Just a stab in the dark but is your battery ok/ alternator outputting correctly to manual figures as an under voltage in the system will also cause a rich fuel scenario.

Also, although the sensors are checking ok, it's worth checking at the pin out connector to the ECU

joe
 

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If your still stuck and can't get the software working, i can do you a diagnostic module that plugs straight into the ecu.

It records all sensor data plus inj, adv, batt voltage etc to sd card about 20 times a second.

Will also display and clear any fault codes.

Send me a pm if interested.

Cheers
Adam
 

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If your still stuck and can't get the software working, i can do you a diagnostic module that plugs straight into the ecu.

It records all sensor data plus inj, adv, batt voltage etc to sd card about 20 times a second.

Will also display and clear any fault codes.

Send me a pm if interested.

Cheers
Adam
This is definitely the way forward and a great resource:yo:

joe
 
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