running on one

[J leech]

Suzuki SV650, 53 Plate injection Model.

Runs on one cylinder, until you disconnect the Air sensor on air box, then chimes onto 2cylinders.

but the problem is when she chimes on the 2 she is running rich as hell!

Changed air sensor, still same, Changed the clocks, Ecu and all associated sensors, Changed throttle bodies and im getting slightly ****ed of with it.

I have checked the diagnostic code and it keep throwing out the code for the Air sensor?

Note to add, all parts i swapped over were from a Known Working bike! and I dont mean the temp one left handside of air box when i say air sensor,


Surely it cant be the loom?

Anyone had similar problem, or any other ideas?

[jambo]

Hi,
Just before we go down this route can you confirm that When the bike's running you can plug the sensor in and out and the 2nd cylinder chimes in and out with it? There is no possibility that there's any other factor?

That being the case, put your sensor onto another bike to check it's OK. Then start tracing the wires connecting the ECU to the sensor and check that they're OK and not leaking to earth.

Jambo

[J leech]

Yes i can confirm bike when running, and whilst connecting/disconnecting sensor she chimes onto 2 when D/C and 1 when conected, All sensors replaced with new ones No wores leaking to earth as far as can be told!

Why would it be running healthy rich when disconnected? this standard for them?

and also to note i have by passed side stand and clutch switches, But bike had ran for 2 years faultless.

[jambo]

Yes i can confirm bike when running, and whilst connecting/disconnecting sensor she chimes onto 2 when D/C and 1 when conected, All sensors replaced with new ones No wores leaking to earth as far as can be told!

Why would it be running healthy rich when disconnected? this standard for them?

and also to note i have by passed side stand and clutch switches, But bike had ran for 2 years faultless.

I would assume without the air box sensor, there is nothing to tell the ECU how dense the air is, so it runs on the richest map available which is safe, but inefficient, rather than lean.

If it's not the sensor, the wiring, or connectors seem to only logical components to check.

Jambo

[J leech]

Like i am changing the loom tomorrow then! Any tips?

[J leech]

Ok just a little update, Today i was hoping not to have to remove the loom, So i have covered all the bases and gathered a little more info!

Swapped Coils, Ecu, Sensors and Injection Bodies! All to no avail!

Right hand side at rear of airbox we have a sensor with a mulit plug going into it, and a Vacuum pipe linked to the front cylinder injector!

With this sensor D/C and bike started she runs on 2 cylinders!

With the Multi Plug Connected again and the Vacuum pipe D/C the bike runs on 2 Cylinders.

This sensor is sending duff info somehow? I have changed the sensor, with a Brand new one and its still same??

What does the sensor do? can anyone advise me on this, perhaps make it clearer for me to understand! many thanks guys!

[Spanner Man]

Good morning.


That is the IAP (inlet air pressure sensor). As you've substituted it, let's assume the unit itself is ok. To test it's supply disconnect the plug, & measure the voltage between the red wire & earth, you should have 4.5-5.5 volts. Then test between the red wire & the B/Br wire, which is the centre one in the plug. You should again see the above voltage.
If you don't have the above voltage present, you may have a poor connection on the ECU, or a break/iffy contact in the wiring harness.

As to why it runs with the vacuum pipe disconnected, it may be because the pipe is kinked or blocked, & the sensor can't read anything. So check the pipe to make sure it's clear of obstructions, & correctly connected at both ends.


Cheers.

[Bibio]

As to why it runs with the vacuum pipe disconnected, it may be because the pipe is kinked or blocked, & the sensor can't read anything. So check the pipe to make sure it's clear of obstructions, & correctly connected at both ends.


Cheers.

or split/leaking

[J leech]

Good morning.


That is the IAP (inlet air pressure sensor). As you've substituted it, let's assume the unit itself is ok. To test it's supply disconnect the plug, & measure the voltage between the red wire & earth, you should have 4.5-5.5 volts. Then test between the red wire & the B/Br wire, which is the centre one in the plug. You should again see the above voltage.
If you don't have the above voltage present, you may have a poor connection on the ECU, or a break/iffy contact in the wiring harness.

As to why it runs with the vacuum pipe disconnected, it may be because the pipe is kinked or blocked, & the sensor can't read anything. So check the pipe to make sure it's clear of obstructions, & correctly connected at both ends.


Cheers.

the IAP sensor has been swapped for a good one, But i will try the Voltage check today!

As for the Pipe, No obstructions or kinks.

Its a nightmare, That gives me something else to check anyhow, Thanks for the info

[J leech]

The Wires to the IAP sensor are reading correct.

If i get the bike to run with everything connected, The rear cylinder when not firing, i remove the plug which is BONE dry.

So at this point in time, The rear injector is not firing with it all connected! Although when i D/C the Plug or Vacuum pipe to said Sensor she fires onto 2?

I am at my wits end with this one!

anymore ideas?

What else would stop the injector firing, Bearing in mind i have swapped injectors, Bodies, ECU etc etc!

[Spanner Man]

Good evening.


Bit of a nightmare indeed.

Have you blown through the vacuum tube to make sure there's no blockage at the engines end? Also make sure the other vacuum take off on the throttle body has got it's rubber cap securely attached.


Cheers.

[J leech]

Good evening.


Bit of a nightmare indeed.

Have you blown through the vacuum tube to make sure there's no blockage at the engines end? Also make sure the other vacuum take off on the throttle body has got it's rubber cap securely attached.


Cheers.

Yes i can confirm, no blockage, New Bodies fitted also?:smt022

[Spanner Man]

Good morning.


The mystery deepens! I would try running the vacuum tube from the IAP sensor to the other cylinder, just to eliminate the remote possibility of it being a fault with the engine.
The sensor is governed by engine vacuum, & if it was low on the one cylinder, due to a leaking valve or similar then it could send the wrong signals to the ECU.


Cheers.

[J leech]

Good morning.


The mystery deepens! I would try running the vacuum tube from the IAP sensor to the other cylinder, just to eliminate the remote possibility of it being a fault with the engine.
The sensor is governed by engine vacuum, & if it was low on the one cylinder, due to a leaking valve or similar then it could send the wrong signals to the ECU.


Cheers.

Ran the vacuum pipe to rear cylinder, Just the same.:rolleyes:

[Spanner Man]

Good morning.


I know that you've changed the throttle bodies, but if for some reason both pairs of throttle bodies were excessively out of balance it's possible though unlikely that you could get the symptoms you have. After all, an engine needs air.
The balancing screw is on the throttle linkage, on the right of the rear throttle body. It's the one that moves a lot when you open the throttle.

With the engine running, try turning the screw, but make careful note of which way you're turning it. Try turning it at least a turn in either direction, & see if anything happens.


Cheers.

[J leech]

Good morning.


I know that you've changed the throttle bodies, but if for some reason both pairs of throttle bodies were excessively out of balance it's possible though unlikely that you could get the symptoms you have. After all, an engine needs air.
The balancing screw is on the throttle linkage, on the right of the rear throttle body. It's the one that moves a lot when you open the throttle.

With the engine running, try turning the screw, but make careful note of which way you're turning it. Try turning it at least a turn in either direction, & see if anything happens.


Cheers.

would say safely they bodies are not out of Synch, as when she is on 2 cylinders she is running very sweet!

A little more insight into situation arose yesterday!

Spoke to Previous owner, and he said that bike ran 100% perfect, at the manx Grand Prix, Due to the fact he finished on the Podium, the front Cylinder head was removed, And after re fitting this is when this problem has arisen? could it be something Mechanical?

What is swaying me away from this idea, Is the fact he finished the season off, after the Manx with the IAP sensor disconnected, so bike still performed very well.......

[Spanner Man]

Good morning.


You would be surprised at how well some engines can sound when the balance is well out. It will cost you nothing, take 5 minutes & anything at this stage is worth a go.



Cheers.