The only way to really tune the MAF, VE, Maf being stock or not is to have a wideband and make sure that what its displayed in the AFRx10 table is what you get in the wideband. Period. The injector and offsets are dead on and that you tune the MAF and or VE tables so that it gets where it should be. Later when you want to be a little richer or leaner you know exactly what to expect out of the car when you change the VE table and not just do some conversion. Granted it will take a lot more time but hey, this is not a race to who tunes faster.

 

But why would the PCM IAC counts be at 87 or so if its stalling out? I've tried playing around with the fueling, yes I altered my Open loop table a lot but at idle I try to run her leaner because I found she runs better this way, if I crack open the TB blades it seems the PCM keeps wanting to close the IAC even on decel even more, I ran her with the same open loop tune on the other PCM with no problems, on the other PCM my iac was at 109 on decel or so, so the PCM was trying to keep the car from stalling, but with this pcm on decel its at 87 & if I crack the blades open more she closes even more so its doing it on purpose. I finally put in "28" into all my IAC follower tables & she seems ok but I didnt' need those kind of settings with my other PCM, this is stupid.

BTW at cruise what AFR do you aim for? Like do you use a wideband or something to know for sure? like how would you know if your running lean to the point where the headers are glowing or something at cruise, I mean o2's are hard to read when its a bit lean, mine jump around at most, & at idle they stay at 80mv or so, but I find its fine at idle with that voltage since my cam is big & on a 109. What are you o2's reading at idle? It seems that if I run the o2's higher voltage then that at idle the car doesn't run as smooth.

Matt.
Matt.

 

I have never understood why you guys attribute a "she" to the car... a femenine car???

anyways... make sure your IAC counts are in the vecinity of 30-50. so the pcm will have room to adjust.

Bunker do you have Cat conv?

 

No cat-conv, the PCM can go all the way to 160 if she needed more air but she doesn't, its weird how the same tune in a different PCM is acting totally different, I mean all pcm's are the same!

BTW the "SHE" attribute is sweet

 

In all honesty, your stock O2 voltages are USELESS on a large cammed car in my opinion. I have never used these to tune, they only plug the holes in my headers. they are worthless.

Since you said u tried changing the fueling and it didnt work, are you sure that you copied your CLOSED THROTTLE SPARK ADVANCE table to the new PCM file ?

As far as the throttle blades go, you need to set them up so that when your car is in neutral at idle the IAC reads about 50, and with the A/C on the IAC should go to around 80. If you set the IAC too high or too low it wont have enough room on one side to maintain the idle.

 

I have more then enough room, at idle I'm at 70 or so, I can't crack the blades open anymore, I'm using the holley TB so it doesn't have any bypass holes, she ran perfect with the old PCM thats the thing & the IAC counts can go all the way to 160 if they felt like it but the pcm chooses to be stupid for some reason, & yes its the identical tune just uploaded into this pcm.

BTW I use the o2's just to see if I'm not too rich since if you rich on the o2's with a big cam then you're really rich IMO at idle my o2s are at 80mv which would be lean on a stock engine but seems fine with mine, I think that equates to something like 18:1 A/F.

 

What about if you go into closed loop mode ? does it do the same thing?

Did you try this same tune in your old PCM in open loop mode ? or just closed loop ?

 

Well said. Experimentation does take time, and that's the only way to do it, ever setup is different. One component that is getting undermentioned is spark advance. This where an infrared exhaust gas analyzer is key, but most tuner shops don't have them (starting price range ~$3000) You can find them at emissions testing locations, but getting "tuning time" at an emissions station isn't going to happen at most location.

EGT's can also be very useful, but still aren't commonly used when tuning our cars (I'd love to see that change.). They lack instant response, but they can help greatly with tuning. For example if you add more timing and exhaust temperatures continue to decrease, then you know you're headed in the right direction. Unfortunately too much timing will cause NOx emissions to rapidly go up, and only a 5 gas analyzer is going to tell you that.

Hope this helps,
-Christian

(wish I had an 8 EGT setup, that would be fun to play with.)
(p.s. sadly cylinder balance tables aren't referenced at WOT, but that can be changed :^)

 

[QUOTE=bunker]I have more then enough room, at idle I'm at 70 or so, I can't crack the blades open anymore, I'm using the holley TB so it doesn't have any bypass holes, she ran perfect with the old PCM thats the thing & the IAC counts can go all the way to 160 if they felt like it but the pcm chooses to be stupid for some reason, & yes its the identical tune just uploaded into this pcm.
QUOTE]

Hey Matt,

I've been where you're at. I've blamed it on bad IAC learning in the past. It's really annoying when you throw in the clutch and the idle drops so fast it almost stalls. Do a search for IAC relearn procedure, that should help out. It's not the PCM, use the stock follower tables just to prove that point.

Disconnect the battery, resetting the pcm, make sure the throttle is closed when starting it the first time, give the IAC a chance to learn. The IAC could be kludged up with carbon, but I doubt it, since it was just fine.

Give it a try, let us know how it works out,
-Christian
(a.k.a Christian Millard ... a.k.a. Puff puff give)

 

(p.s. sadly cylinder balance tables aren't referenced at WOT, but that can be changed

and how do we do that if you care to share.

 

Wow I didn't know the off idle tables weren't referenced at WOT, learn somthing new everyday. Needless to say, I got it to run ok I just cranked the TB blades more & put 28 throughout the table, its running perfect again, but with different TB opening & different values in the IAC tables which weirds me out.

 

Glad to hear it's behaving now Matt. Damn irritating IAC's, sometimes no rhyme or reason to it.

I suspected the off cylinder balances weren't used when I couldn't get the AFR balanced between the two cylinder banks using dual widebands in the headers. One side is traditionally leaner than the other, I was just trying to correct for that. I altered tables to an extreme with no difference, so I asked a person very knowledge in disassembley to confirm my thinking and he did. He also altered the code to reference a new table - WOT cylinder balance, but I never tested it. Considering he's been working with embedded systems for over 20 years if he says it will work I trust his word.

Unfortunately, like most things, to do the job right would require an 8 EGT setup. The shop actually has the EGT's, but I don't believe they have an 8 channel card to accept the input from each of the EGT's. I see Dataq just came out with one though (only $895 w/o thermocouples - ouch)

http://www.dataq.com/products/hardware/di1000tc.htm

okay, back to your regular programming,
-Christian

 

ASk rskrause.. i believe he had the 8 egt setup some way.

 

Will do, I know John up at MBA had an 8 egt setup, not sure if he still does.
Would definitely be neat to tune with such a setup.

-Christian

 

No kidding, I"m definetly suffering from this effect, I think this one has lots to do with drivability since if you have a split & the o2's correct for it, they might be causing more problems then there already are.

I belive this is how mine is screwy:

IDLE: LEFT O2 Richer/ Right O2 leaner
ON DECEL(fuel shut off): LEFT O2 Richer/ Right O2 leaner
PART THROTTLE: LEFT O2 leaner/ Right O2 richer
Accelerating high MAP: BOTH O2's pretty much the same, at times reversing from cruise
WOT: LEFT O2 Richer/ Right o2 leaner (950/902)

So you can see how irritating this can be, I tried swapping the injectors side to side with no difference what so ever, next is swapping the o2's around, hardly doubt it'll fix the problem, I think its the effects of a big cam & reversion is the problem, but then what about WOT runs? LOL, I notice that when I get my A/F within acceptable limits IE. 12.6-13.0 at WOT, I see this split, if I'm running rich IE. 11.7-12.2 I see not much of a split at all, this become very irritating when you try to perfect everything in your car ie. get your valve train geometry all perfect, make sure your installed heights are all the same, pushrods perfect length, use lash caps, set rockers while engine is up to temp & idling etc... I do all this to prevent such things, but what the heck.

At one time with my old setup everything started looking good one day IE both left/right bank were pretty even, but i was down on power, turns out one of the lifters poped a plunger, so a mechanically unsound setup showed up real nice on the scanner

Matt.