It uses one coil for two cylinders. Therefore, to kill spark to one cylinder, you'd also kill it for the other.

 

you just pull the wire off going to the one cylinder that branches off the coil. That would eliminate one cylinder.

 

I don't think I can intelligently comment on the subtle change in the running quality of the engine (which is all you get when you drop the timing on one cylinder) when it is running on three though!

 

Hey jcsb,

Does the stock ROM code calculate a knock sum for each cylinder with the knock sum that we log being the sum of these values?

 

Unless you code it to not fire one cylinder.

I guess if it was easy enough to be able to code to not trigger the spark event for one cylinder you could pull the plug on the other cylinder if running 3 is easy enough on the engine. Banging on 2 only would probably be a more dramatic change from 3

 

Thats what I was thinking but I had a brain fart. Physically speaking when the coil fires it fires both cylinders. However you can still figure out the 1-4 cylinders and 2-3 by turning that coil off. And/or you can make them run 10 degrees off of eachother and figure out which pair is which with the timing light.

Would it be too much to assume in the code that the injectors share the same cylinders as the spark?

 

mrfred, each cylinder event the knock interrupt calculates the increase in knock sum which is added on to the knock sum. I have taken this increase in knock sum and add it to a new set of four variables - one for each cylinder.

Yesterday I fitted an FQ360 high flow cat (previously decat) with 3" flanges and also went back to my usual 99 RON. I now have knock sums up to 7 under full load at 5000+ RPM (often less, have to drive it hard to do that), and the cylinder distribution is rather different to the previous random/noise knock sums I had before. I will selectively retard each cylinder to see which is which.

dan l I haven't looked much further at the coil and injector code, need to do so.

 

Yeah, I mean I'm grasping at straws with the injector. However we can do an injector disable per cylinder and its easy to identify which cylinder isn't getting fuel. If you can match that up with the spark then I'd ***-u-me that they share the same numbering scheme.

 

They do, but the time when the coils and the injector time are scheduled can be different. Coils can be on falling or rising CAS pulse, injectors are probably well before.

 

__________________________________________________ ___________
I wanted to look into if there were any improvements with ECUFlash out of curiosity. You said the bad Cylinder may be 3 or 4. I wanted to post a link to a thread I made a long time ago.
individual-cylinder-question
DTM stated this:
"Actually its the A/F ratio that is of greatest concern.
When doing testing on a bone stock bottom end with individual EGT and WB outputs (1 year ago) We found a difference of over 1(+) in cylinder number three. This comparison was done with stock and hks cams, stock turbo and 3" TB. By using the AEM cylinder trim features we were able to dial all cylinders into a + or - of .2.
Power was up over 13 hp without timing increase. Just a thought.
Keep in mind MANY MANY things can effect the outcome of power as you already know. This is just one case that each cylinder should be treated as such, independently for maximum reliability and power output. "
And also this:
"Without getting into too much, the AFR differences were greater in low load and low rpm. At one point the AFR had a differential of .8 to 1.7. Cylinder number three consistently became the culprit with the highest cylinder temperature.
We probed all four runners 1 1/2 inches from the port on the bottom side of the runner with EGT and 2 1/2 inches away were the individual WB outputs.
After adjusting individual cylinder fuel percentages in a linear fashion, we were able to come within .2 of a point on average during full throttle pulls. Under specified load (mustang dyno constant speed) the AFR became a bit more erratic between cylinders as we encountered slight rich misfires. Once we upgraded to an HKS DLI, even under constant load the AFR remained pretty consistent. Averaging now in the .3 range. At this point, please don't take it the wrong way, I will only give certain information about our findings. 1/2 a point of AFR differential betwwen cylinders can be ok, but you are talking about a forced induction (4cyl) application that generates a lot of heat and friction. Ask almost anyone here on EVOM to do a compression test on their STOCK blocks. You will find that 9.5 out of ten people have a 20psi drop in cylinder number three. It is inherent to the design of the engine and its associated components. We merely wanted to find out what it is actually processing during its cycle."
And also consider this:
"Quote:
Originally Posted by Second Chance
Tephra I believe its more of the intake manifold design than a difference in the injectors. #2 is the leanest cylinder as that is what most people run there EGT's and the cylinder that most have damage on in a failure.

The order in which we concluded was the leanest to the richest:

2
4
1
3

So your post is extremely accurate. "
__________________________________________________ _______________
I wanted to help out anyway I could, I thought posting this up would assist in your tuning. Any information you may find can help others as well. I still have not learned how to tune with ECUflash, I am still wondering if an individual cylinder tune with ECU flash is still possible. I think taking A/F ratios into consideration along with knock as a tool at least DTM had a great starting point and was willing to share it.

 

^^^ Very interesting, cheers for posting that up

 

let me see if I understand this,

cylinder three flows the least amount of air. it is at its worst before forced induction.

being too rich it was also found to be the hottest, this I assume was indicated by exhaust temps and may indicate exhaust temps from a cylinder that is not to hot but that is exhausting unburnt fuel into the manifold.
The point being, #3 becomes less likely to be the knocking cylinder (regardless of fault) while cylinder # 2 & 4 look like they, while being held lean by the ecu trying to balance afr, are overly lean and inclined to wildfire. Though the poor afr incurred at low load the heat may extend up into the pull.

This also brings up the recurring complaint of evo tuner nubes like myself who see off wot knock and have had a hard time tuning it out. Hard to say as the wonderful tests posted above do not say at what load the third cylinder cleaned up. How much of the condition happens during closed loop? That answer determines the bandaid fix.

very appreciative of the testing!

 

Bump for MrFred reply- I know he's testing that silly-noid.

 

Why are you substituting a RAM address for the array address? Is this to enable live adjustment of the individual (timing?) trim value?

 

I wanted to also note something above because I had a question concerning timing... above they tested out with an HKS DLI, I just read a post about some "spooling" company that offers COP. That got me thinking, could you use COP to tune this timing thing better? Would that help at all or make a difference? I know that on page 2 or so of this thread it was mentioned about pulling off a plug or some jazz but that doesn't make sense. If you did a mechanical mod, COP, would that get you your individual timing? Also, I think the theory of individual tuning based on A/F is basically, rely on timing to be erratic so it can maintain a smooth combustion process. If you tune on knock, that just means you're working harder to achieve the same results, but won't get the same results... just a thought. If you messured A/F while you are adjusting the timing etc, then at least you have a tool to messure your other results to.