Cadillac Powertrain Control Module (PCM) Tuning Discussion, Going MAFLess? in Cadillac Engine Technical Discussion; And to continue that thought, as said in some threads on the SS board, no-MAF cars (i.e. speed density) tend ...
And to continue that thought, as said in some threads on the SS board, no-MAF cars (i.e. speed density) tend to be best for power and speed in a lot of cases, but they just can't compensate for random changes surround environment and air, etc. It can basically only depend on and use whatever programming has been done and that's it.
N0DIH can probably say a lot more, though, as he has had great success with it.
All I really know myself is that I've yet to be dissatisfied with the year round feel and performance of either of our OEM Mafless cars--the '93 FWB and '92 Roadie--so, aside from other clear performance differences, I want to try it on the '95, which has left me wanting in a lot of ways that are clearly due to tuning.
Here's some questionable threads, albeit made up by people who never actually had the correct tuning:
The key is good VE table tuning. If that is wrong, it will never be right. People like to move the IAT, all that does is shift the VE Table indirectly. AFAIK it doesn't matter where the IAT is, as long as the VE Tables are set right it will always be fine. Cadillac 4.5/4.9L PFI cars have the IAT in the intake manifold.
Most cars have a poorly setup VE table. It is set to the 5-13% low everywhere (lean) in the table. So for it to be a dead on 128 BLM, it MUST use the MAF as a correction OR ditch the MAF and correct the VE. The VE tables are used always, some believe that they are not used with a MAF, I have proved beyond the shadow of a doubt, they are used 24/7.
When people dis the idea of not using the MAF, they likely are saying they don't know enough about it to tune for it. It DOES take more work to tune, but I feel it is very rewarding to do. And my BLM's are so stable it amazing. I only see it go lower in BLM under slight throttle decel. Which honestly isn't a big deal, but when I have time to fuss I work on it.
I have been narrowing down split BLM's too. I have almost no splits now. (this is where the left and right bank are one rich and one lean)
As for springs, mine will rev to 5900, but it just isn't making as much power there. Maybe it will make more with new springs, but with stock it doesn't give me indications of float, but just doesn't make the power that it does at 5400 rpm. It is like I passed the peak power of the cam or heads and power is going down.
Those 2 links on Impala SS forum are showing how little people know about MAFLess tuning. I would never go back given a choice.
Myths of MAFLess tuning by N0DIH:
1. It makes the car more sensitive to changes: FALSE! It might be a narrower range before you should retune, but hardly makes it sensitive. You add headers to it, you will see BLM's move off into the lean range. But with stock VE tables and a MAF vs tuned and MAFLess going with headers, or cam, you will be very close to the same hosed up BLM's.
2. You need a dyno to tune for MAFLess: FALSE! You need a tool like VEMaster and some time to run some datalogs. You WILL need a custom PCM tune to dial out DFCO and PE Mode for a while, or be prepared to do a lot of manual editing of the datalog before you run it through VEMaster.
3. You have problems with VEMaster and Split BLM's: TRUE. If you study your datalogs and see split BLM's, VE Master will not fix it. It will likely be worse with it. Work carefully with your Idle and Off Idle Individual Fuel Trims to dial out the splits and then return some new datalogs to VEMaster. I use VEMaster up to 5500 (max it goes to) and let my VE Tables be as correct as possible, then PE mode when kicked in will be accurate for the amount of fuel multiplier it is going to give. THIS is where you need dyno tuning. But any car, MAF or MAFLess needs this for peak power production.
4. Car won't run without a MAF: FALSE. It will, but it must be disconnected prior to turning on the ignition. It needs to fault out first, you will be now running strictly on SD mode, but with a fault and ugly VE Tables. Key is not to run it with a BAD MAF, either good or none.
5. Moving the IAT helps power: FALSE. It hoses up the VE tables. Moving it will offset the VE Table range. So keep it where it is when you tune. If you move it, fine, move it and then tune. You toss all the calibration off when you move things around after a proper tune.
6. MAF is a restriction: TRUE. ANYTHING is a restriction. But not always much of one. But honestly, the mid range of my car feels better without and mine is 90% stock as delivered from GM. Do expect some top end. MAF's aren't terribly fast reading, the air in the MAF is not the air in the cyls, it takes time. The MAP reads what is in the cyls, as it is a depression, so the air in the cyl at the time the intake valve is open is what the MAP sees, the MAF is seeing measuring the air when it is quite a large distance away, probably 2-3 rpms, quite possibly more.
6. MAF's are a bandaid to weak factory tuning: IMHO, yes. I think it is a EPA requirement, as nothing today doesn't have a MAF, can't prove it though. It allows the car to adapt to users playing with things and putting on K&N's and such, or even cams and exhausts. It gives an additional correction factor. Proper tuning removes the need for it. But, if you do a major change, more power is seen by a proper MAFLess tune than leaving the MAF there and letting it do the corrections.
7. MAFLess cars are faster in the 1/4 mile: According to my sources down under, always. From tuners who have tuned as best they can MAFLess, then install the MAF back in, the car ALWAYS slows with the MAF in place. Numerous people have done it.
IMHO it is one less thing to break, one less thing in my intake tract, it is sweet to have it missing. I won't go back.....
From what I have read, I agree with him. Proper tuning and MAFLess is very rewarding. Even without it still runs fine, you would be hard pressed to prove that it really runs different with vs without the MAF. Tuned it runs better, definately more precise, my BLM's statistically are very very solid and close. +/- 3.5 or so for ALL conditions. And I am narrowing it down more. And the split BLM's are all gone (that is not something MAFLess helps/hurts), I have been carefully working on them too. Split BLM's if you are wondering is when one bank of the engine is lean while one is rich. The computer compensates, but there isn't VE tables on one side or the other to tweak.
Just to bring this thread up to date a little more, after LOTS of back and fourth emails between me and N0DIH (mainly because of my non-stop questioning ), he's been working his magic on a new MAFless tune for my '95.
Still waiting on my cable to send him the correct current program from the car, but can't wait to see what his extremely attractive Fleetwood V4P/Vette tuning will do to the current slosh tune--both in trans shift modifications and other things to eradicate the use of the MAF. Hopefully, all turns out well, and I can experience the same thing he's been doing with his own '94.
Very, very nice to have an actual Fleetwood guy in the know about ALL of it, as well, and over and beyond willing to help and answer any question
Well, finally got all set up and read and sent my current stock PCM file to N0DIH early this past weekend...now just chomping at the bit to get his custom tune for me and get rid of that MAF! Really even more curious now that I just did my K&N intake and noticed a bit of a difference with that.
I've had a tune from N0DIH for a little time now, both one to run currently with the MAF and another to run so I can datalog and get information needed to program the MAF out. Still haven't had the time to do the latter, but regardless, liking the new improvements from N0DIH even with the MAF.
With his combo of V4P Fleetwood and Vette specs, nothing huge, but my overall power delivery seems to have gone from soft to authoritative. Shifts are spaced out more appropriately, are no longer just soft slips from gear to gear, and it just feels both more responsive under typical acceleration and if you plant it more while cruising--not as dead as before.
Still a lot of other fine adjustments to make, probably, but N0DIH knows what he's doing for sure, and I appreciate it in the biggest sense--can't wait to keep seeing what he can do, once I get some Datalogging down, the MAF out, and other things touched up.
N0DIH: Essentially just emailed you the same thing at your work address, so we'll chat again whenever. Thanks for the immense help so far
Yet again, another PCM update from N0DIH, and whew it's yet again a whole new monster.
Even sharper shifts, and placed so to make acceleration (particularly from a stop) very authoritative, AND at least initially, my gas mileage seems to have gone up a tad as well--it'll take more driving to really see.
STILL haven't gotten around to doing the datalogging and starting on getting rid of the MAF, which is the main topic of this whole thread, but getting there eventually...