Only just found this site and looking a bit of extra help with my Hayabusa engine. Recently put the engine back in after overheating from losing a core plug 3 years ago!!.

Engine was removed and had to get 0.012" skimmed off the head, all back in again and not pressurising any more. The problem I now have is when the vacuum hose which runs from the throttle bodies to the map sensor is connected, it runs really rough before cutting out. So far I have checked fuel pressure that is currently sitting at 43psi with the fuel pressure regulator vacuum removed, also carried out a compression check and all four cylinders are sitting at 200psi. one thing that I can see is that I have a 3pin plug on a small loom under the throttle bodies and have no sensor to connect it to. I do think it was never connected but cant remember as its that long ago

Any ideas?

is it throttle position sensor? what colour are 3 wires?

If you post up some photos then you will get the best answers.

Thanks for the replys, its not for the TPS as its connected but I think its on that loom. one other plug on the same loom has a air sensor and then I have a spare plug. i will take a pic tonight and pop it up.

thanks

are you sure you've connected the vacuum tubes to the correct sensor? There is also an atmospheric pressure sensor which looks identical but is left open to the air - if you mis-connect them you'll get the symptoms you are describing (I've been there).

I will take pics tonight but it has a vac pipe coming from one tb to the fuel pressure reg and then it has vac pipes from all 4 tb's running to the map sensor. That's all it ever had. No other sensor but a spare 3pin plug.

http://s743.photobucket.com/user/dianne_mckechnie/media/IMG_0112_zps13d966cc.jpg.html?sort=3&o=0

That looks like the airbox temp sensor connector. What kind of airbox do you have? Look under it for a connector which will fit.

However while it may be the cause of your issues I doubt it - when its disconnected the ECU will just assume a temperature and fuel accordingly - might make it perform sub-optimally but shouldn't give the rough running you are describing.

In fact, maybe not - would be 2 wires to the temp sensor....that might be the plug which is supposed to go onto the atmospheric pressure sensor (the one I suspect you are missing or mis-connected to) - I'll nip out later and check mine....

yes I have got a sensor for the 2pin plug, but not one for the black 3pin!!. I had all the parts stored in a box from I removed the engine so that's what makes me think it was never connected to anything. But the engine was running 100% other than boiling up b4 I removed it.

Just had a look at my car, here is the atmospheric pressure sensor:

Hayabusa Atmospheric Pressure

Wire colours don't look the same, but depends on year of engine/loom.

It could be that you have swapped the plugs for the intake sensor and the atmospheric sensor - I believe they are interchangeable. You should have an atmospheric sensor - are you sure its not still on the car?

The sensor that you have in you pic is what I was calling the MAP sensor, I have one of them and the wire colours are the same as yours. This is the sensor that when I connect the vec hose to it starts to run very rough won't rev and will just cut out. I don't use the air box just a sausage filter, and the only other sensor I have is brass with a green end that my 2pin plug in my pic goes into.

If you are sure the wire colours are the same as that (think they are Black/Brown, Green/Yellow and Red) then that is the APS - you definitely don't connect the hose to that.

It would suggest the Intake Pressure Sensor (IPS - what you call the MAP sensor) is missing. It looks identical to the APS and should have Black/Brown, Green/Black and Red wires - thats the one you connect the hose to.

This would definitely give the symptoms you are describing.

Yes my wiring is black/brown Green/yellow and red and I will take a pic of the sensor that I have pluged into it.
Also can I ask how to upload a pic? Lol

OK I have sussed your problem. The sensor in the photo is the atmospheric sensor. and should be breathing air not vacuum. the connector that you have shown which remains unconnected should go to the MAP sensor which should also be connected to the inlet manifold vacuum hoses. So when you connect the vacuum hose to Atmospheric sensor it thinks you are up mount Everest LOL. So you need to find another sensor which looks identical to the one in the photo except it is screwed by one screw not 2. connect this to your manifold and hey presto.

Kind regards,

cosmick

First of all I would just like to say a very big thank you for all the help that I have been given. if you have a look at my pics this it the sensor the plug with the black/brown Green/yellow and red wires is connected to.
Now I have the garage pulled apart looking for my lost sensor!!!!

http://s743.photobucket.com/user/dianne_mckechnie/media/IMG_0116_zpsaa926577.jpg.html?sort=3&o=0
http://s743.photobucket.com/user/dianne_mckechnie/media/IMG_0113_zps69d140bf.jpg.html?sort=3&o=3

Yep that confirms it. this is the Atmospheric sensor so the engine will run much better with it disconnected than connected. And yes, you need to find the other sensor. You are obviously not using a Suzuki dashboard as, if you were, it would have an FI light on all the time. You really need to connect both sensors to get the best out of the engine. The MAP sensor is most important and once correctly fitted will make the engine run normally.

Kind regards,

cosmick

I use a stack dash and the engine its only back in after sitting on the bench for 3-4 years!! and lets say I was not happy when I started it up and it was running like a bag of bolts, all sorts was going through my head. ie valve timing with having 0.012" skimmed of the head. lets just say the engine was 1/2 way to being back on the engine stand again. but now I have been saved all that trouble with the help of this site.
now all I need to do is find my sensor!!

Kind regards
Paul

Hi. Can i ask for some more help! i have looked in every box in my garage tonight for my missing sensor and i cant find it. all i can think of is that it fell of the vac hose at some point. Can i now ask if someone would be able to help me out with a part number for what i need, as i have seen some on ebay

this one will do the job. Suzuki GSXR 600 750 K1 K2 K3 Air Pressure Vacuum Map Sensor Denso 01 02 03

Got my map sensor today from ebay, went to plug it in and my plug on my wiring loom is to small for it. can i ask would someone be able to have a look at there sensor and see if they can see a part number, my engine is year 1999 or 2000

15620-02F00

Kind regards,

cosmick