Why is it that people often state that the MAF needs to be retuned? Retuning the MAF seems akin to retuning a coolant sensor.

One of my favorite aspects of the MAF is how little tweaking it needs even after the most radical of engine changes.

 

Lets see, between Ed, Loius, Frost and Patrick I think we have some of the best and and talented tuners, who like to share some of their secrets, replying that the air needs tweaking and then you say that tuning the MAF isn't needed. Hmmm, who should we take advice from.

They are all tuning and cam experts and each actually goes at some stuff different ways, not like spin on CF who quotes the same cam for every application.

 

Thanks guys, we may mess with it today. I will keep everyone posted for the hell of it. I am sure my LS3 won't be the last with a surging problem.

 

If you look at it like that, your car will never run right, or It might run right, but could it run better!?

If you knew Jackson ( MrDrezzup) you would know that he is a BIG DIY guy, and takes a little but of knowledge from a LOT of people, and then forms his own conclusion. Ill let his reply slip Ive even bailed him out of strange and odd situations.

Im not the best tuner, There are other people that are better than me, but I hit the LS3 C6 market HARD, and faught a LOT of these issues from the get-go, and thus, learned a LOT from each car that came through here.

Im slow at older PCM tuning... I end up racking my brain because they do not come through here as often as the new cars.

So having said that, fueling requirements with the MAF are very critical. Some say you need to not tune the maf- I will argue that you DO need to touch the maf, because at certain airflows, the fueling requirement CHANGES when you change big parts, like cams.

The CURVE is still a curve, and it MUST look like a nice MAF curve. If its hacked, it will run bad, and transitions will be poor.

Look at every aspect of the cal

 

i have the same problem with my lg g6x3 in my ls3 98 camaro!!! what the hell is it? car has been tuned by mikey at rapid and jeremy Formato. same **** going on light accel between 2000 and 4000 rpms! already did the plugs and gaps too!!

 

If you have EFIlive send me a run log of it surging/bucking, and send me your tune.

We'll discuss what it will cost. I guarantee I can get it straightened out.

edcmat-l1@msn.com

 

Ed, I'm looking for someone local to me with EFIlive to log it. Unless it gets resolved first. I will let you know soon.

Thanks.

 

Also, FWIW the maf tables are stock, untouched. I also drove it (with 3 different tunes) as low rpm as I could. 30mph in 4th @ 1200rpm and it bucks...BAD.

We are going to load a stock tune since it looks like some timing values have been changed. We'll load a known complete stock base tune and go from there.

 

I am not saying the MAF does not need to be tuned. What I am saying is that I have seen the most radical of changes and yet the MAF curve is still very accurate.

 

I agree that the curves shape stays similar but it moves to reflect the increase in flow. GM was lazy and made them pretty broad but not that much.

 

That was an amazing effort on your part and I am still grateful to this day! :-)

As for the DIY part...my car is on its fifth camshaft, fourth set of heads, and third engine. :-)

 

HPT will work too. I have both. I was just saying EFIlive to the other guy cause he has it in his sig so I figured he had his own software.

His is bucking from 2-4 grand which is ridiculous. I get pissed when I can't make em stop surging at 1200-1300 rpms. LOL

 

I can tell you for a fact,most everything Ed tunes drives perfect.We had a pretty big cam in an ls7,i had that thing in 6th gear at 800rpm just cruising.

We had an ls3 car recently that had a much bigger cam than a 228 232,that car drove damn near like stock.I'm not sure what Ed does to them to make them drive like they do-but it freakin works!!!!!

 

i have efi live for my duramax so i can copy it but salt on roads now and its cold!!! lol maybe few months but cars in right now! send me pm so i can save your info and what todo. thanks aj o yea someone told me g6x3 is big cam!

 

Email is edcamt-l1@msn.com. I should be up in Pitts in April or so. May wanna check back with me in late March if you're interested in a tune.

 

I like this thread.

Three very good tuners that I have learned alot from with slightly differant approaches, and there is nothing wrong with that.

There are several methodologies to tuning these motors which are effective.

the process itsnt asmuch of the factor as the end results.

I have my tuning check list to follow, but they have their mental experiance check list that is very effective.

The guy that had two tuners retune your car, . lol that cost $800 bucks for nothing

 

haha $800 try $1200!!

 

Thats your problem there ^^^ Simple fix and some good logs and you would be good to go!!

 

I wasn't clear when I meant the MAF tables were stock.

We were worried that when I showed up to get the tune (car surging) the previous tuner who also installed the cam (21 CMC) may have skewed the MAF tables. It turns out that the MAF tables were left unchanged, though that may have led to some of the surging.

We should be messing with it this weekend, I hope. It will be great to have this resolved.

Many thanks to everyone

 

So is it working,

This is all caused by airflow, it is 99% airflow as soon as I read it I new straight away.

While The main spark advance going back to coast down spark smoothing helps i can say that is not the issue here,its an easy fix, getting VE right is important first also the MAF table. Fuel trims, e38 is so fast that it will correct it, without showing any sign of lean or rich running.

First I cannot stress how important it is to have the VVE or HPT 2 .5 bar VE tuned correctly before even plugging the MAF back into scale it. If you haven't done this it is most important, also using more timing in low load cells will smooth it out, but this accounts to a small part of it.

My bet is the Max idle area limit, Its nothing else, been there done that all running 20 deg overlap cams with e38s.

Because you ported the TB it is increasing airspeed past the blade dramatically, no matter what the other settings you change it will still buck,the effect of reversion is the main cause and having to much base airflow at 0% PP. you want to come for a drive in a e38 car with a 240s cam on 111lsa that idles like and drives like stock and if u lived in Oz I would let u drive mine.

E38s are no different to tune then any other ECU all the principles applied are the same but GM set the airflow tables up differently in the e40, e67 and e38.

When you drive the total TP% is max idle area or max idle fail in HPT, In efilive its around 1.8 in HPT its 60. The e38 will use max idle area plus PP% pedal position. Now as soon as you get off the gas it will pull right down but the transition on it u will notice there is an e38 hard limit. Yes I spent a lot of time working this out but because know one else new how to do it I worked it out myself, Initially I helped only my mates out and kept all hush hush, but now cause so many ppl spend heaps on tunes and there not right I simply share the info to everyone for free.

Simply reducing these values will fix it, but might idle worse, you retune the idle then, most e38 powered cars sound like they idle like rotaries with cams, well they should sound like a carbed V8, its because of all the e38 correction going on, some of it is important to modify some arent. All in all stock TB MAF tuned e38s are a piece of **** to tune any tuner can do it including idle and drivability, port the TB start changing stuff, going mafless or eliminating surging much more to it, some tables do nothing some do a lot. I get em driving very nice and very awesome throttle response.

Anyway, I haven't done any write ups with HPT, there is stuff I have figured out with it you cannot do with efilive and basically I am not sharing it

BUT I can help you with surging with efilive or hp tuners.

At the end of the day reducing these values limits airflow at slight throttle positions, if you are logging sae.tp its base is around 18.8% add 3 % pedal thats 21.8% surge city if you can reduce this back down to around 18% including having the pedal depressed 3% the surging will entirely go. Finessing fuelling and timing will improve it further. Also changing injector timing will help.

A few guys here have pm'd to say thanks as they were frustrated and had done everything, This helped a lot.

Again this will improve your idle. Once its 99% there is a few tables to get into to finish it off which again I had to learn thats the e38 for you. All I can say is a lot of the stuff in the e38 I do not use but some of it is very important.

I basically my same approach to tune all ecu's with large cams, my focus basically is to make big cams idle stock and I think I have achieved this. If you still need help please pm me. Some comments I got were "now the shops no how to do it" well I hope they learn. The difference between learning tuning and doing a degree is they tell you how it works in a degree at university and C's are acceptable. With tuning, you gotta work it out yourself, like I did when the e38 come out, and you gotta achieve 100% in all your tests. They way I see it I share my research with other tuners who then try to perfect something I have started and thankfully its all good news. I share info with all tuners not to get anything back but to help them it may mean the difference of someone passing an emissions test somewhere who knows. The info is there for all to read. I have a lot more stuff that is yet to go on the forum. I don't feel I am giving away secrets people still have to grasp it and use it with what they currently do.

http://forum.efilive.com/showthread.php?t=9740

It basically outlines idle tuning, but the key element max idle area is what comes into play here, if its right everything else falls into place.

Please note though on a MAF tuned car if you feel it idles well reducing max fail from 60 to 40 or there abouts and in efilive from 1.8 to around 1.2 that this is a good starting point.

Thanks for sharing everyone but I think you will find this will fix his problem.