CW00BlackTA

iTrader: (31)

Using HP Tuners after a heads/cam install. Dialed in the VE table using an LC1 wideband per the procedure documented in the HPT Help section. All was good. Reconnected the MAF for calibration. First log session I noticed at WOT the AFR started fine at around 13 for a second, and then it shot up to around 22--at which point I immediately let off. The data at medium frequencies indicated a small amount of error. At higher frequencies things were way out of whack and the resultant curve was pretty jagged. I tried a few more things with the same result. That lean condition certainly isn't commanded anywhere. The only thing I can conclude is there is something wrong with the MAF (an 85mm GM unit with a Z06 curve). Anybody got any other ideas? Going to check the sensor and connector wires on the MAF now. Thanks in advance.

JonCR96Z

iTrader: (33)

Post the log and tune.

69LT1Bird

iTrader: (1)

Did you bother tuning the MAF in MAF only mode after you tuned the VE tables?

CW00BlackTA

iTrader: (31)

Tried that and got the same result. When the MAF is operating, soon as I go WOT the AFR heads for about 22. Doesn't happen without the MAF.

Frost

iTrader: (45)

Yes!

If it's a truck MAF, you are probably close to it's end, but it sounds like you just need to finish your tuning.

WeathermanShawn

iTrader: (1)

I am going to ask the 'dumb' question here. Are you 100% sure you have DFCO disabled?

Forgive me if I have misunderstood where you are at in your tune, but sometimes the lag between your wideband AFR and TPS can lag (depending on how many parameters you are logging).

A few times while logging at WOT, if I took my foot off the throttle and unsuspectingly engaged DFCO, the external wideband log vs TPS would have a lag. I.E., would show a brief lean spike while TPS would still read 100%.

Again, I may be way off here..But that is a scary AFR reading if valid.

..WeathermanShawn..

CW00BlackTA

iTrader: (31)

checked the DFCO enable temps and they are set at 284F--which should disable it.

Having problems with home computer which is why I haven't posted the tune or scans.

Pulled MAF, checked wires, cleaned and reinstalled. AFR went to 20 pulling out of the driveway. End of trip. Ordered new MAF. We'll see what happens with that.

Billiumss

iTrader: (11)

Are you logging MAF freq?

If that drops to zero during a WOT run or normal driving your MAF took a ****.

macca_779

Sounds like a good excuse to just ditch the MAF entirely. You've got the VE dialled in so why bother spending more money on it.. Just bin it.

69LT1Bird

iTrader: (1)

There is nothing wrong with using a MAF if you know how to tune. I am running in MAF only mode right now and it works great. I have tried all three ways now and if tuned properly any of them can be used.

Billiumss

iTrader: (11)

Yep, thats the truth....

A lot of people ditch the MAFs cause they don't know how to tune them or with the VE table.


MAFs correct for weather changes, SD tunes don't... Proven for over 25+ years.

macca_779

You've got to be kidding me. Its the other way around. People retain MAF's because they don't know how to tune SD or they are just plain lazy. God how good would it be to just force a MAF full time. Would half the time it takes me to tune a car

MAF's do correct for weather to an extent but they aint perfect, not by a long shot. SD has a lot of processes available to correct for all conditions. I tune SD more often than not. Pressure is accounted for in an SD tune no problems at all.. The PCM knows Baro after all. Temp on the other hand is the main area most people will see drift. That issue is resolvable via the charge temp blending tables. Or if you have EFI LIVE as HPT doesn't have it. A custom OS with a VE/IAT factoring table makes it very easy to account for all temp drift issues.

SD will give improved throttle response and the potential for more top end power due to the removal of the MAF restriction in the inlet tract.. Been proven not by time. But by experience.

gametech

iTrader: (1)

Umm, NO. A proper SD tune takes into account any weather, elevation, temperature, or other environmental changes. I could train a retarded helper monkey to tune a MAF. What an SD tune will NOT account for is changes to motor parts. A MAF will partly handle this. In a perfect world, a MAF would handle ANY changes, but in the real world this just doesn't work. There are very real hardware and software limitations that restrict the ideally unlimited potential of a MAF tune severely.

macca_779

Bingo. This man knows what he's talking about.

There are way to many myths circulating about SD tuning and obviously not enough education on how to do it properly in the USA. If there was it would be embraced a lot more often. Hell there were a few high end perfromance model LS1's released here from factory with the MAF removed and tuned 100% SD.

69LT1Bird

iTrader: (1)

No one said that a SD tune was not good, I was simply defending the MAF. I have mine fully tuned, the VE tables are all dialed in, the MAF is dialed in. I just wanted to test the MAF only idea and it works very good on its own, I do not have any throttle response issues. Trying different things is not a bad thing, learning new ways to tune is always good.

If you having a bunch of training information that you would like to share, post away, I am always willing to try new stuff.

It takes a big engine or FI to make a 85mm MAF become a restriction.

Billiumss

iTrader: (11)

You guys are too funny... "SD Tunes can account for weather changes", NOT... hahahaha

I guess you guys don't really know how a MAF really works then, IT MEASURES THE AIR MASS! Cooler air = more dense, Hotter air = less dense. Basic physics guys.

The FI guys (big dogs) would love to have MAFs on there cars but can't due to the limitation in the OS, the MAF gets maxed out. The newer LSx stuff has a higher limit so you can run more boost. The Mustang guys all run MAF only, even with boost. Do some research on the Ford/Mustang systems, they run pretty damn well for MAF only.

I've tuned dozen and dozens (probably more) of cammed LSx cars/trucks (with Wideband O2) and after a properly calibrated VE and MAF table, the throttle response is better than a 100% stock car (unless a HUGE cam). Even the car owners have noticed it.

For extreme engine combos, I can see doing a SD tune but for the average person with a cammed LSx, a MAF/VE combo works perfect.

A lot of people are going MAF only on the newer LS3/LS7 combos due to the Virtual VE tables and its a pain to tune it properly.

Since you guys know more than GM, I recommend you contact GM and tell them that the millions of dollars invested in the new C6 ZR1 program is all BS and a waste of money since the ZR1 has a MAF on it and it doesn't work.

I'm not going to debate this anymore, it has been debated over and over again on here for years and MAFs do work when its properly tuned along with the VE table.

macca_779

Its like talking to a brick wall with the MAF lovers. There is no benefit to using a MAF except for simplicity in tuning.. Thats it, case closed.

JonCR96Z

iTrader: (33)

What really accounts for weather change is the O2 sensors. Either way is going to be corrected by the O2s.

Do you know how the MAF works? It uses varying electrical frequency to power heating elements in the sensor, trying to maintain a set value. More air cools the sensor thus requiring more Hz. Since this uses actually uses air temp to work it some what better than SD for correction, but like you said "Cooler air = more dense, Hotter air = less dense" so air temp also effects manifold pressure. Which has an effect on an SD tune. If the resolution was a little better in the VE table it would be nearly the same as the MAF as far as accounting for temp change. In the end though the O2s do the real work.

shoemike

iTrader: (25)

With EFILive Temperature Blending is MAF linked. (lbs/min or gps)
It's not making changes itself but it is a reference for other tables to make the changes.

WeathermanShawn

iTrader: (1)

I agree with Jon96Z that the function of a closed-loop via the narrowbands is often overlooked. I know closed-loop does not get a lot of respect, but if you can get accurate readings via the O2 sensors..then the difference might come down to resolution of MAF Frequency vs MAP & RPM.

I have ran both 'SD' and MAF at times. A peculiarity I have noticed with open-loop tuning in SD involves the differences in air density that comes with altitude change. I have noticed BARO does not update that frequently (engine off/on, TPS >37%, etc). So for the same RPM and MAP the air density change that occurs from temperature and or/elevation seems to lack the resolution and response from MAF. You might think that the equations handle air density changes from elevation accurately, but they assume a linear relationship (which is not always true).

But, my main point is that whether SD or MAF, if you can run closed-loop..there is some logic to it.

Hey, I know everybody gets tired of this same discussion, but I thought I would at least share some of my expieriences. I have just noticed those peculiarities in running 'SD' going up a few mountain passes around here. What seems like it works great via equation, is not always true when you toughen up the test.

Now, whether the MAF is better or not, I will leave that to the engineers to debate.

Thanks.

..WeathermanShawn..