No. The air/fuel is dependent upon how much fuel is delivered. It has very little to do with where the timing is at.

 

So it's possible to have such a dramatic reduction in power with the same amount of fuel delivered and not have unburnt fuel in the exhaust?

 

I'm not being argumentative, just thinking outloud.

In all fairness, moving the timing in either direction (+/-) of the optimal setting would result in reduced power. The specific setting that achieves the highest mean combustion pressure will produce the greatest power

I wanna add that I DO understand that the factory timing maps have ignition retarded somewhat (5-10 deg.?) from the optimum setting to reduce peak flame temp and the attendant NOX emmisions.

 

But looking at the torque graph on the "normal " run ...especially the area below 4k... WJM, that motor's producing such fat torque in the lower revs that I'm inclined to think that the timing is bumped ahead of factory settings. No?

 

What I'm saying is that aside from the abnormal dip, it looks like it's running exceptionally strong.

So it's possible to have such a dramatic reduction in power with the same amount of fuel delivered and not have unburnt fuel in the exhaust?

 

I'm not being argumentative, just thinking outloud.

 

Correct. AFs stayed the same during that drop.

 

I wanna add that I DO understand that the factory timing maps have ignition retarded somewhat (5-10 deg.?) from the optimum setting to reduce peak flame temp and the attendant NOX emmisions.

 

But looking at the torque graph on the "normal " run ...especially the area below 4k... WJM, that motor's producing such fat torque in the lower revs that I'm inclined to think that the timing is bumped ahead of factory settings. No?

 

What I'm saying is that aside from the abnormal dip, it looks like it's running exceptionally strong.

 

yeah, after the new knock sensor was installed, its running a TON better under 1/3-1/2-2/3 throttle conditions.

 

However, as far as I am aware of, this tihng is completely stock.

 

WJM

So it's possible to have such a dramatic reduction in power with the same amount of fuel delivered and not have unburnt fuel in the exhaust?

 

I'm not being argumentative, just thinking outloud.

The same thought crossed my mind, but since the dyno runs are WOT (open-loop), the 'puter won't be actively changing the amount of fuel based on a "misfire" event the same way it would if a misfire were to occur at part throttle.

 

I don't know how A/F is calculated during WJM's dyno runs, but a tailpipe reading would definately show all sorts of anomalies regarding changes in HC, O2, and NOX. The EGT at the ex port would change quite drastically, etc. The more parameters that are recorded during a run, the greater amount of data available to use in identifying the problem.

WJM, can you plot other parameters during these runs? Spark angle, injector pulse width, etc.

 

Are you going to do some dyno runs with the new knock sensor?

WJM, can you plot other parameters during these runs? Spark angle, injector pulse width, etc.

 

Are you going to do some dyno runs with the new knock sensor?

 

No.

 

I already did. Those last runs posted are it. Pay attention to the captions for the runs.

 

I think I'll see about putting the wideband into the header next time....I had a wideband at the tail pipe. Its proven to be 100% accurate on all the other cars we dyno and tune.

No.

 

I already did. Those last runs posted are it. Pay attention to the captions for the runs.

 

I think I'll see about putting the wideband into the header next time....I had a wideband at the tail pipe. Its proven to be 100% accurate on all the other cars we dyno and tune.

So, the A/F readings were from your wideband EGO sensor? If so, I would think that it would show misfire as a lean A/F ratio: It senses free O2, not HC, and there should be lots of free O2 in a misfiring exhaust stream. Does this sound reasonable?

So, the A/F readings were from your wideband EGO sensor? If so, I would think that it would show misfire as a lean A/F ratio: It senses free O2, not HC, and there should be lots of free O2 in a misfiring exhaust stream. Does this sound reasonable?

 

something like that....but normally it knows to ignore those misfires, as the ECU picks up on it.

something like that....but normally it knows to ignore those misfires, as the ECU picks up on it.

I was assuming that the tailpipe EGO sensor was dyno monitoring only, not connected to ECU.

I have a 2004 legacy wagon and a 2006 WRX (previous owned a 2004 WRX).

 

Pinging with the turbo models were also major issues, especially the 2004. The ECU's seem to come from the factory tuned rather lean in an effort to obtain the ULEV status. I have had my 2004 legacy in to record my complain about pinging, but, the subaru mother ship claimed nothing was up. The ECU mappings are just stanky in an effort to lower emissions. If you see a 2004 dyno chart, you see similar activities - around 4000 rpm timing was being pulled because of knock detection (similar to the initial dyno charts in this, but not quite as drastic). A/F rations would run 14.5:1 and then drop quickly to 10:1 near the time knock was being detected. Knock was removed from a lot of ECU's via aftermarket remapping! YEAH! (I think a sarcastic smiley would be nice to have) So, running that close to 'perfect' combustion, adding something like a K&N filter which allows more air into the a/f ratio could be enough to trigger a lot more knocking because of being even more lean (as noted by the other dyno chart on this post - which was GREAT!)

 

So, higher octane or a really dirty air filter may help reduce knock. or maybe an intercooler... hmmm...

Ummm....out of all the stock ECU'd WRXs and STis we've had on the dyno...100% of them were 9:1 ARFs or richer under boost...and NEVER above 14.5:1 during cruise.

A/F rations would run 14.5:1 and then drop quickly to 10:1 near the time knock was being detected. Knock was removed from a lot of ECU's via aftermarket remapping! YEAH! (I think a sarcastic smiley would be nice to have)

 

Here ya go =>