I have been desperately searching for this info for about a year now...

I was reading a tuning manual somewhere (can't find it anymore) in which it was discussed about how cylinder #1 runs more lean than any other cylinder on a 4G63.

I have had two tuners blow my engine twice due to cylinder #1 detonating. It is getting very expensive to learn this:

How much extra fuel must cylinder #1 receive as compared to cylinder #4. How much extra fuel should cylinder #2 get as compared to cylinder #4. Finally, how much extra fuel should cylinder #3 get as compared to cylinder #4.

Every tuner that has tuned my car has kept the fuel the same across all cylinders. I can clearly see that there needs to be a graduated difference in fuel flow across all four cylinders. What is it? 10% #1, 6% #2, 3% #3?

On the AEM, is it + or - fuel trim?

Thank you for your time.

strike

 

screw the fuel trim, take ignition out of the cylinder.

unless your running individual laf sensors in each primary tube, it's just a guess on how much fuel to add.

 

Take ignition out of the cylinder? What do you mean? Reduce the amount of spark? That does not even make sense. If you mean not letting cylinder #1 fire at all, then I would only be running on three cylinders... How exactly is "taking ignition out of a cylinder" a reasonable solution?

Since there is so little information about this, I am assuming this is one of those "voodoo" secrets that everyone holds close to their chest. I wonder if it is possible to poke holes in all four runners out of the exhaust manifold and sample from there. That would theoretically solve all of my problems.

strike

 

Moderate your tone when you are talking to someone who is trying to help you out!

Just like fuel trims, the AEM has ignition trims to adjust for differences between cylinders.

To do this via offset fueling you would need to monitor conditions in each cylinder seperately via either 4 wide band sensors, or 4 EGT probs.

Why are you tunning so close to the ragged edge that this makes a difference?

Keith

 

From what i know, the #2 cylinder run's the leanest. thats why most people place the EGT on the #2 exhaust runner, and why some people speculate that mitsu placed the knock sensor behind the #2 cylinder.

 

I think that you misread my tone as I had no intention of being or sounding rude. It is to be expected in a text forum though. I do apologize if anyone has taken offense.

Now, to the ignition stuff, are you saying that less of a spark will cause less detonation? I am not sure how that would work. I will poke around in the software tonight though and see if it makes any sense to me. Thank you for pointing out that feature.

I am not tuning anything yet. I am still in Iraq and every time I have come home on leave, I have had someone tune my car for me and the engine blew. The first time was because the tuner was a moron and got fired from the shop he worked at. The second time seemed to be some sort of corruption to the CAL file. Once the CAL file was uncorrupted, I hit 7k rpms and blew the engine again.

Every time, it was cylinder #1 that had maximum damage. Cylinder #2 would show some damage as well. It was detonation in all cases. This means that #1 is going lean. I have plenty of fuel available (big injectors, fuel pump, etc) so I am assuming that if I change the fuel trims on cylinders #1 and #2 that the detonation will stop or affect all cylinders at once.

strike

 

After looking at the ignition stuff under advanced, it appears that you guys are suggesting that I retard timing on cylinder #1. Is that correct?

Why would retarding timing be better than adding fuel? All else being equal, the most likely culprit is a lean condition due to the design of the throttle body (magnus ford). Wouldn't it make more sense to add more fuel to cylinder #1? Would retarding timing cause odd harmonics?

Hmm, you guys have given me a lot to think about. That is pretty cool. Thank you.

strike

 

Has nobody changed their fuel trim to account for more air flow? *sigh*

 

Woohoo! I am getting an exhaust temp sensor implanted into each exhaust runner for each cylinder. I should be able to tune each cylinder much more accurately now. Seven more weeks and I will be home and tuning my car.