Now this is getting better. Notice the more accurate actual A/F ratio at WOT (target 13.2:1) and normal/quick lean spike during deceleration. This bike won't pop and is almost perfectly tuned. Believe it or not, tuning to this level of detail takes several hours per cylinder.

 

Shops are more interested in getting better peak numbers. Thats the easy part. They lean out the top end of the map and get some nice gains very quickly (factory bikes are actually rich at WOT with supresses HP).

Now, here is a pic of effort to tune at steady throttle at about 2800 RPM's. The Target A/F is 13.2:1 and notice that the actual A/F hovers right around the target point. Tuning to this detail is right at the limit of the accuracy of the Delphi system.

I can say with 100 percent accuracy that doing this without the right equipment is impossible.

 

wow, thanks all.
think i need to print all that out and chew it.
also just got the good news that my SERT arrives tommorow..!!!....perfect timing as a week later i go touring thru europe....hopefully with less popping by then.

 

FL799,

OK then, if I put some positive figures in my PCIII map at 0% throttle and around 2750 rpm (now still all at zero), my decel popping will be less??? So put in 1, 5, 10, 20???

You guys seem to know your sh$t - awesome.

Stealership told me after my custom dyno that there will ALWAYS be popping on decel.

And they did tune out that rich condition a WOT as you mentioned.

Cool stuff. THANKS


(priceamp - my second major of choice was EE, but I thought that crayon coding system for resistors was just kinda elementary '77 ChemE UMass Lowell - plastics)

 

Well I proved fl-799's statement that if the bike is so far out of tune, decreasing the enleanment table doesn't get rid of the popping. At least I guess this is my issue from not being able to reduce the popping.

Last night I installed an SERT on my FXSTi and flashed the ECM with a reduced .75x enleanment table. Took the bike for a ride and there was no improvement in popping. Flashed the ECM with the suggested .5x reduced enleanment table from this and other bulletin boards. Took the bike out and I thought there was a slight improvement in reduced popping, but while riding to work today, it's a definite NO improvement.

The good news is that the SERT installed with no issues. I was able to read ECM information and successfully flashed the ECM using a USB to Serial cable conversion twice. Wish the SERT had the capability to read as well as write. I would have like to view the maps for the HD standard download that was flashed in the ECM and compare those maps/values to the ones that came with the SERT for a given hardware configuration.

Now, back to square one!

 

fl_799
In a earlier post, you recommended "to eliminate popping, add VE value increments at the 0 map above 2750 RPM's until the popping goes away. Might take several increments."

Of coarse I assume this applies to both cylinders?
When I do this, should I reset the enleanment table back to the reference table?
Or leave it at .5x of the reference table like I have it now?
Or does it not matter what the values are in the enleanment cells?

Also, I think I read your reply to a similar question, but I can't find that post, but, why does raising the VE cells at the 0 map reduce popping, when it would seem that raising the VE values would increase the volumetric efficiency thus increasing the air flow, which leans the mixture? And I thought the popping was due to too lean a mixture? Intuitively, it would seem you would want to reduce VE increments, not increase?

And thanks for taking the time to upload those graphs and educate us on mapping etc. Good stuff. Think I'm starting to catch on a little bit here :-)

 

Sorry for the delay in reply's....

Back a few posts there was some talk about tuning the PC III. I did download the software a while back and don't see why the same tuning techniques used with the SERT would not directly translate to the PCIII.

As far as tuning the VE tables are concerned, without using a sniffer of wego, I'd add equal amounts of VE increments to both front and rear cylinders. To really dial things in, you need to modify the air/fuel table too. All the VE tables do is allow the ECM to accuratly 'hit' the target Air fuel ratios in the A/F table in open loop only. Remember, 2 increments equals 1 percent fuel change. Increasing the ve values equals richer.

Pics to follow.

 

fl799 who you asked is best to answer this, but in the meantime just to check if i understand right, from reading the sert manual (theres a copy on this forum n the diy section)
i think by raising the ve value, you are only telling the bike that the vol. efficiency is greater, but in reality you know it is not.
the ecm then thinks it has to counteract to keep the desired afr, and so it adds fuel as required.............
well at least i think thats the case. im still tryn to get to grips with this before i get my sert...tommorow hopefully..........[sm=smiley29.gif]
but wait for confirmation from someone else before acting on that......

 

The VE is an actual number.

For example; the A/F ratio of a particular table is 13.5:1 at 30 map at 4500 RPM's

The VE table at that same point has to be tuned so that the sniffed air fuel reading equals 13.5:1

If the sniffed A/F ratio for that particular area is 14:1, the VE value needs to be raised several increments to meet the 13.5 target.

 

So the VE table is the method that the ECM uses to hit it target in the air fuel table. But all the VE table tuning in the world won't do you any good if the actual A/F target is bad. Here's the '06 Dyna stage one map. Mostly closed loop and extremely lean in several portions of the map. Pretty bad unless you work for the EPA.