Rich/lean problems

[KetsMcLets]

Hi

I had the exhaust manifold off the other day for welding and noticed something rather alarming, The first cilinder seems to run a little bit rich and the other 2 are quite lean as you can see in the picture I took.

My first thought was 2 clogged injectors or something. I didn't have a remap for the exhaust I must admit, but wouldn't that affect all three cilinders? I did notice that the first cilinder is a fluent bend into the exhaust and the other 2 sit at a 90° angle in the first one's bend (if that makes sense) but can this influence the lean running? seems unlikely..

Anyone know what it can be or is it something that's happened to anyone before?

Needless to say I want this sorted before I go on the rollers where they take the average lambda of all 3 cilinders

thanks

 

[CanberraR3]

Just checked mine. My no 2 looks a bit like your no. 1. Throttle bodies maybe need balancing - mine did.

 

[KetsMcLets]

Thats a vey good point, didn`t think of it but bikes mostly have itb`s yes. Thanks! My tuner`ll have to sort it out then..
Any pointers on how to do this? Vacuumwise i guess like carbs in the old days ??

 

[Pedro]

You can use one of the ecu programs Tuneboy , or Tuneecu ( this one is free you just need to buy a cable) or you can use a vacuum gauge with 3 separate Indicators and you just balance 1and 3 to match 2.

 

[Torque addict]

I've been wondering about this and this seems like a good place to ask... does anybody know with only one MAP sensor how does the ECU know what the vacuum is in each individual throttle body? I see the three individual lines from each throttle body teeing into the one large line to the MAP sensor instead of three sensors. I'm guessing it uses the ignition timing to know which cylinder the sensor is seeing at any given time but that would have to be a very responsive sensor and I just can't see the vacuum being able to change that quickly. Please enlighten me.

 

[ROCKETHEAD]

I've been wondering about this and this seems like a good place to ask... does anybody know with only one MAP sensor how does the ECU know what the vacuum is in each individual throttle body? I see the three individual lines from each throttle body teeing into the one large line to the MAP sensor instead of three sensors. I'm guessing it uses the ignition timing to know which cylinder the sensor is seeing at any given time but that would have to be a very responsive sensor and I just can't see the vacuum being able to change that quickly. Please enlighten me.

You answered your own question. Sensor might not be that responsive but ecu calculates over certain intervals...

 

[idk]

It combines input from the vacuum hoses and the crank angle sensor to determine the vacuum in each cylinder. I posted a "How To" thread on balancing the throttle bodies. It is quite easy (assuming you no longer have the OEM air plumbing) and well worth doing.

 

[Torque addict]

I assumed corectly for a change. Nice. I will balance them next time I get a chance to.

 

[KetsMcLets]

Another stupid Q from me: I can't seem to find the how-to section in the forum index, any links?

 

[ROCKETHEAD]

On the .com site...