Alright I'll tell you.

We begin by logging the data in say datamaster, find out where your long term counts hang around, say ex. 123 BLM & lower, at idle say your at 122 or whatever for longer terms. Take the highest long term count & record it, you will need to know this to tune idle, say the highest long term count durring whatever condition was 129blm for example. No problem, what you will now do is set a barrier, you do this easily.

Say at idle your MAF afg's are registering 11 AFG's, ok, go to the MAF table & everything from 7 AFG's to 18 AFGs I'd lean out, Note the frequency the original 7-18 AFGs was cuz you'll change it now, now say multiply by 90%, tune your car now & watch in closed loop what the Long term counts are now, say they went to 135 BLM, note this, go back to the MAF table & multiply the same area (frequency) for idle MAF readings by say another 90% just an example, save this & tune the car. Observe the Long Term blms at idle, say they are now 145BLM, Note, I would say a 234/242 cam 145BLM LT is good, say 240/250 cam I'd go with 155blm being good.

Now what you will do is go back to your previous highest BLM which was 129BLM, You now know that no matter what driving conditions the max your Long terms went up to was 129BLM, but now at idle they are going to 145BLM, go back to the tune & Limit the Long Term BLM correction to 130 BLM.

By limiting the Long term to 130BLM you are within your driving condition corrections & now the PCM will not correct past 130 BLM, at idle your short terms will rise to 145 BLM & the Long Terms won't compensate, the short terms will remains at 145BLM & all the time at idle only because you set a limit to the Long Term correction & altered your MAF table to achieve this.

On my cam I'm running about 155 Short term BLM & car runs great. My max Long term is set to 132 because thats what I had to have to not interfer with off idle corrections & yet stop the pcm from compensating at idle.

so a 234/242 say 847 cam I liked 145 Short term, with my cam now I like 155 short terms because of more overlap.

There you go boys, I thought of this all on my own

If some of you need to know how to limit the long term blms, the newest tunercat tunner has the limit option. Not the KEEP ALIVE BLM but the regular MAX BLM number is what you alter in tunner cat. If someone doesn't have this, once you figure out where you want your BLM email me your tune & I'll put the limit on to whatever to help the few first guys out.

Matt.

 

Actually... i have done that before... but found that the PCM got all a bit crazy with the STFT resetting and starting again and it made the car not smooth at all at idle...

Did more or less the same thing, but dealing with the injector constant... Since i've been w/o my car, i thought i will try the blm boundaries and set them up over 1200rpm and see how it went...

Anyways guess i will try all this out again.

 

Shouldn't be resetting at all, are we talking about the same thing bud? If you're talking boundries thats a completely different thing bro, I'm taking max/min blm LIMIT not boundries.

LMK.

 

I understand that... the problem i had was that my STFT did something like this:

started at 128 when pegged to the 135 limit i had set to the LTFT... then ...the stft rised rised rised rised rised.. hit max.. went to 128.... start over... rised rised rised rised.. went to 128 start over... i was WTF?

The other thing is i do not know how to make my car go into close loop faster. It appears i have a timer or something similar.

I guess i will use a GM update bin from my SPS and start from there.

 

again bunker.. IM NOT sayiny you are wrong at all....

i agree its the best way if it works like you describe...

Just.. that it didn't work for me with my cal.. i will try with a newer gm cal...

The other thing is.. what you did with the blms to never go over 129 that is the best idea...

I wish there were a blm blocker for the idle like there is for the WOT.

 

Hehe thanx yeah it works just try a different revision of tune, mine is off a 94 F-body so try that, my long terms hit 135 & the short terms stay pegged at 155 & thats how it stays thruout, I can show you a log if you like aswell.

 

Been there, done that, worthless. The PCM will change the tune.

but if it works for you thats awesome

 

it works for a buddy of mine. when i did it.

how can the pcm change the tune. clarify

 

I had thought of that before, but never tried it.

I just wish I could figure out why my wideband won't give me accurate readings at idle...then I could use a pe idle for this.

 

it may not give accurate readings because there is not enough flow through the sensor or because of the same problem the stock sensors have.

 

the long term and short term fuel trims even when the BLM correction factors were limited still wouldnt stay put and my car would go from stalling lean at idle to running a touch rich. Back them down even more and it would just stall.

but then again my cam is larger than any of yours, It just wont work for me. I use speed density and a wideband.

As for the wideband not working at an idle question......There is a setting called sample rate in my LM1 wideband unit. At idle apparently the exhaust pulses are not moving fast enough to be accuratly measured. But you are supposed to be able to slow down the sample read rate of the wideband O2 sensor for this reason. However I have not tried to mess with this yet.

 

Ok I'll post a log off my car later on today so you can all see.

Matt.

 

I was pretty sure that it was a problem with the exhaust not moving fast enough across the sensor. Looks like I'll have to read through the manual and find this.
Thanks!

 

Odd, I am running a 236/242 dur. cam and do not have any issues at idle. My blm's were slightly high at idle but adding a little fuel through the individual fuel trim at idle table solved that. My idle is bumped 50 rpm over stock and my maf table is stock.

 

The problem isn't that, with a big cam when your fuel trim is perfect it really is too rich, the extra oxygen that passes through the overlap fools the o2s into thinking its too lean, o2s compensate until everything for the o2s is perfect while the mixture is way too rich you just don't know it because of the fresh oxygen that flies through the overlap.