Since scrapping mths and mths of prior tuning/chip combos, i've thrown out the old and started over from a stock chip(millionth time:-)) for some odd reason and some fancy calculations to get my ve tables in the 128 range even with changing the inj constant. With canister purge shut down(temp) and PE set for 70% tps and higher im running almost dead even 126-128 from 1100rpm to 3000rpm. All readings and data figuring for the blm was all done in the 23-30C range on the MAT with coolant being about a 5-8 difference in temp at the same readings. After going back out several times to verify my true blm's i came home and reactivated the canister purge.

The next drive out and once the ecm relearned, my previous 126-128 blm readings changed to 122-124, all other things being the same ie.. coolant mat etc, even the outside air conditions..

Is there a satisfactory way around the effect the canister purge has on the blm or do i dial it in 128 w/ the purge off and then just tweak it slightly(lean out) for when the purge is usually on?


Im just blown away at my latest results and striving for the perfect 128/128 (as close as humanly possible)...

Any thoughts or opinions on what u guys have done or which way i should fly with it to hit 128 across the board feel free to drop your two cents...

I searched for posts but i could only find ones relating to shutting the canister purge off for tuning and what effect it has and im trying to figure out the best way to manage 128
thanks
jeremy

 

No need to, you'll be chasing weather conditions.
128 +- 7, is just more then fine.

Remember when running closed loop you just averaging 14.7 and the ecm is toggling over the 14.7.

If you want to get really serious, you'll go open loop and then use a WB to find out what AFR the engine runs best at.

Off course this suggestion is for off highway use, and none cat equipped cars.

 

Ok since im doing very well in that dept , 122-132 under almost all verifiable driving conditions in the last 3 days. For invoking highway mode will being in the 128 +- 7 be acceptable as well, because that is what i am going to play with next.

Anyone want to see some weird numbers re-invoke your canister purge and dont clear the ecm before u make a run :-) hehe all kinds a goofy stuff till it learns its way back to mostly normal lol

Guess that rules out any further tinkering with my canister purge as long as u baseline and get your blm close to 128 as possible.

thanks for the reply grumpy and hopefully u will drop me ahint here :-)
love this list for figuring out the fun stuff
thanks guys
jeremy

 

Bruce is right. In fact, it may suggest that you may want to look at "tweaking" the MAT Inverse Lookup Table to eliminate changes due to the incoming air temp.

While this is a "nice to do" if you have the stock MAT sensor in the plenum, it is quite necessary if you have relocated the MAT and live in a climate where there are large variations in the air temperature.

But, with a little patience, you CAN tune the MAT Inverse Lookup table to get 128/128 perfect in virtually all weather. I've tuned mine from -20*F to +100*F ambient air temp with virtually no devieation from 128.

BTW, this is only applicable for SD cars. MAF cars don't rely on the MAT for fuel corrections - they rely on the MAF sensor to detect changing ambient air temps.

 

Are you refering to the practice of trying to get the VE table perfect (assuming all other conditions are constant) or just day-to-day changes in weather that cause a global change in BLM?

 

There are several fudge factors in tuning, and you'll rarely if ever have the PERFECT calibration.

Even variances in fuel between gas stations and the actual fuel temps, can push the *128* off kilter.
And if you really want to split hairs, you'd want to figure in fuel rail fuel pulsations, and it's relationship to PWs.

Just get close, and your as good as your going to get.

 

werd.lately ive been going to higher volume fuel rails with my honda. seems to really help stabilize the idleing fueling being as its runng a batch fire ecm.as it is now 4 50pph injectors sucking from the same rail seems to dirupt the fueling quiet a bit. ive been toying with the idea of a fuel chamber above each injector. i dunno. its pretty good now. at work the sun 450 machine i have says its got a smal deviation of less than .02 psi per injector firing event. i think thats pretty decent.

 

Since we've deviated to this subject now... on my TPI system (in a Monte SS), I can feel the injector pulses when I pinch the return line (I have soft high pressure hose connections). Is it normal to feel such a strong pulse?

 

thanks for the additional replies grumpy, glenn and funstick (and everyone else)....

Im currently working on relocating my MAT into the inlet tract before the tb/plenum with the quicker working lt1 style, just waiting for the harness connectors to come on, so by next week it should be in place and im most likey using your inverse mat table as a starting point glenn :-). probably just reloacate it and leave it alone and datalog a few times and see what happens before i play with the inverse table.

As far as my canister purge problems and dropping my blm after it was reactivated, most parts of the VE table were affected on slightly if at all and only a few spots dropped into the 1-teens so after a few adjustments i was off and running happily again and more or less consider it a non-issue and during driving conditions under normal acceleration and normal highway cruise speeds my blm range from 125 - 129 when completely warmed up with the mat in the high 20's to low 30's. so its working out great as far as i can tell at this point
thanks guys
jeremy

 

I had posted a copy of my MAT Inverse Lookup Table a while back, BUT it was based on my engine's settings and would most likely not be valid for your car. You'd have to redo your entire VE table as well as your spark and injector constant.

My suggestion is to obtain 128/128 (or as close) based on a LOT of data at a certain temp range. Then, as the ambient air temp increases in the summer, look for changes at a specific rpm/mph/load that previously was 128/128 but now off. Even use the same stretch of road. I used a 100 mile strip.

Then modify the MAT table every time the temp varies by 10*F. It takes time, but eventually you will get the MAT table set and find that your BLM/INT values (assuming your initial VE table is well setup) starts to remain very constant.

Good luck.

 

Glenn,
HITHERE have been playing with thew inverse mat table slowly and in little bites at HITHERE time to slowly work it to almost 128 cold and when its hot (im darn close at 20-30C MAT temps), but my newest problem that HITHERE have found that when my MAT jumps up to 50+C and stays there(warmer weather and road construcition) is when the canister purge comes active at those high MAT temps my car begins to go rich . My BLm's will fall to 117-119 range depending on speed (w/ 100% CP) this only occurs when the car hits these temps..

Was playing with TC and checking out the tables and what HITHERE can do but at this point im kinda lost/confused as to how to properly tackle the prob w/out affecting idle or cruising (or vice versa)

any thoughts ?

thanks
Jeremy