Ok guys,

well.. I just got EFILive and I rode around town with it for a little bit.. the laptop screwed up on me p133 with 16mb of ram. Anyway, I lost the file, I'm learning how to mess with all this.. Really neat program..

Anyway, My LTRIMS NEVER went negative.. and for all practical reasons they were maxed out on the positive side.. Riding around town, i saw 20 and 20 on both sides.. every now and then it would drop to 15 or so.. saw them at 9 for a second... This is an EXTREMELY rich condition, correct?

Also, could one of you guys with a little EFILive expirence get with me and help me interprete my data? I am going to be going back into town around 2 and am going to log that data to and from the dentist and would love some help from you guys...

Thanks

 

Your cars base is extremely lean, which will cause the pcm to add fuel add WOT.

 

When you looked at the data, were you just looking at it through EFI Live or did you export it to excel and average the Ltrims? To determine just how bad things are, an average is more useful.

 

Once you have logged some data and have saved a file go into the help file in EFIlive and use the instructions to create a CSV file that you can export to Excel so you can manipulate and sort the data by base load cells to get your average LTFT as well as view the other sensors you have logged. Don't forget if you want to change the names of the columns over to what ATAP calls them you can use this little program to sort the data automatically http://www.ls1.com/forums/showthread...hreadid=245355

<small>[ February 26, 2003, 02:20 PM: Message edited by: J&JsTA ]</small>

 

OK, well.. I did some riding around and made a file.. I won't have time to get it done until later tonight..

My car is throwing a lean code...

Is this something that SHOULD be fixed through adjusting the injector tables? I have the stock MAF...

 

If you set a lean code, then you should fix the prolem by re-calibrating the MAF table. The MAF table that you are currently using is too far off from the actual flow characteristics of your MAF sensor. So what is broke is your MAF table, so fix whats broke and not what is not broke.

 

if your +20 then thats alot to adjust your MAF table.. I dont like going over 110% with any MAF table. But one one car we did his 3000-6000 by 120 and scaled down and he hasnt had any issues.

you can either edit it with the MAF or IFR table...

 

I think I have averaged them right and I am coming up with

21.7 for the LTFT B1
21.5 for the LTFT B2...

So, would something like a ported maf and maf ends help me out? I've read that setting the lean code means that the maf is not seeing the amount of air that it would like, so if I could get more air in there, it would see more air?

What should my MAF readings with EFILive be? The "averaged" rate of airflow (not sure if that helps is 3.13lb/min and MAF Hz is 3751.96747)

Sorry if i sound like a complete moron, but as you can already tell, I'm new to this and appreciate all the help!

You guys rock! <img border="0" alt="[worship]" title="" src="graemlins/gr_hail.gif" />

 

Ported MAF or MAF ends will make you even leaner as it allows more unmetered air to slip past the MAF sensor, you need to go the other way. As for the MAF flow you need to do the conversion from G/sec to G/cyl to figure this out and the formula is on http://ls1edit.slowcar.net/tuning.html or it is on the new table that NBM-WS6 DRIVER is creating with your help(EFIlive data), but from what I have read changing your MAF table that much to compensate can cause problems elsewhere but you will have to read and determine for yourself how you want to procede. More info on MAF table situation in the LSedit archives http://www.ls1edit.com/pipermail/ls1edit/

<small>[ February 27, 2003, 07:26 AM: Message edited by: J&JsTA ]</small>

 

He has seen LTFTs at 20, 15 and 9,,, and now reports an average of 21.7. This does not really makes sense and he should not work with an average. There is one LTFT value for each fuel cell. In all of the cases reported here, it seems that at idle, the LTFT value was at its highest value and as we go up thru the higher fuel (load) cells the LTFT values reduces, in one recent case, the LTFT value goes down to 0% in the higher load cells when at idle it was 25%.

As a first attempt at correcting the MAF table, I would multiply the lower frequency cells (first one up to 3000Hz) by 115%,,, multiply the 4500 to 6000Hz cells by 110%,,, and 7000Hz and up cells by 105%. The omitted cells (3125 to 4500Hz,, and 6125 to 7000Hz) are to be the blending cells.

Up load this new program and drive the car for a good 20 minutes visiting each fuel cells to enable the learning in each fuel cells,,, then take anothe EFIlive log run.

But there is another point here which I do not understand, 2K says that he is using the stock factory MAF sensor. Its very hard for me to accept that the LTFTs are above 20% with the stock MAF sensor. Has anyone else ever seen this???

I saw these LTFT values when I was using the stock MAF with ported nylon ends and no screen.
I just find this situation to be very unusual.

Maybe there is a vacuum leak or a fueling problem.
What do you guys think???

 

I believe 2K just did a header install causing some of the situation <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

I had a look at the CSV file 2K created and 99% of the 4-16 cells were 20s. I never thought of a leak situation but with the fact that they are consistently +20 that could be a possibility <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

<small>[ February 27, 2003, 11:04 AM: Message edited by: J&JsTA ]</small>

 

Ok, would we be talking an exhaust leak? The leak would have to be before the first cats.. However, the leak should also be post MAF shouldn't it? Otherwise a leak after the maf would not effect the maf reading would it? How would I go about tracking this down? I've heard spraying WD40 around the TB and MAF, should a leak be present, will be indicated by an RPM change..

DocSS - I would assume you are the same DocSS on LS1.com.. while doing some research on this topic, I found a post you left. You say this

"On the technical side, if you have a modified factory MAF or an aftermarket one, the MAF table should be re-calibrated for the new physical situation.

If you are still running the descreened factory MAF, then the MAF table is off. It does not represent the true flow rate of a MAF with the screens removed. This is very typical, your MAF is flowing the same amount of air in any given engine load situation, but it is sending out a slightly lower frequency to the PCM, so the PCM is reading less air coming in than actual. That is why the LTFT is positive. "

I have descreened the maf... so my car is reading what it thinks a screened maf should be reading, correct? So therefore, I need to manipulate my MAF table to represent the change in screened/descreened? I understand this amount of air is negligeable, but still would be enough to cause a problem.. Or maybe I should get a screened maf?? I descreened it when I first got the car and a few people told me it was a good mod... now I've read more and it seems some cars don't like it.. Other than that, the only mods on the car are in the sig..

While driving, the harder I get on the car, the LT's go lower.. still positive.. while riding around the guage on EFILive stays tagged out at 20.. the files show that it's actually sitting at 25..

Let the fun begin..

<small>[ February 27, 2003, 02:53 PM: Message edited by: 2K T/A Driver ]</small>

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2K T/A Driver:
<strong> Ok, would we be talking an exhaust leak? The leak would have to be before the first cats.. However, the leak should also be post MAF shouldn't it? Otherwise a leak after the maf would not effect the maf reading would it? How would I go about tracking this down? I've heard spraying WD40 around the TB and MAF, should a leak be present, will be indicated by an RPM change..


I have descreened the maf... so my car is reading what it thinks a screened maf should be reading, correct? So therefore, I need to manipulate my MAF table to represent the change in screened/descreened? I understand this amount of air is negligeable, but still would be enough to cause a problem.. Or maybe I should get a screened maf?? I descreened it when I first got the car and a few people told me it was a good mod... now I've read more and it seems some cars don't like it.. Other than that, the only mods on the car are in the sig..

While driving, the harder I get on the car, the LT's go lower.. still positive.. while riding around the guage on EFILive stays tagged out at 20.. the files show that it's actually sitting at 25..

Let the fun begin.. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That makes a little more sense..... A4s and ported/descreened/maf ends sometimes don't place nice together at all. I had a ported descreened MAF to start with and had a problem with leaness and the SES light so I took it to Wade at ARE and he had a hell of a time workin with it on the dyno to the point where I took it off as he couldn't get it stablized.... it was just to unpredictable (lean like you see on yours)I found it was just not worth it for a mildly modded car. There is also lots of talk about it messin up the line pressure to the tranny and causing problems down the road so OFF it came and you may wish to do the same(some more reading for ya)as there are lots of threads if you do a search between the 2 sites.

<small>[ February 27, 2003, 03:06 PM: Message edited by: J&JsTA ]</small>

 

Yeh, the more reading I do, the more looks like I need to find an aftermarket or stock MAF.. I wish I hadn't descreened it.. ugh.. I just read a post that made it seem like the GMAF was more accurate than the stock maf, although, I may have misinterpreted the info.. Oh well.. I guess I need to start looking.. It's only money right? <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> Maybe I can sell mine..

<small>[ February 27, 2003, 03:12 PM: Message edited by: 2K T/A Driver ]</small>

 

Actually if you do some more readin about MAFs it looks like ppl have had some success with the PACE VV but that seems to be the only one that has regular good comments about it, but most say you don't need anything more then our stock MAF until you get to 500hp and up

 

I have a question / suggestion for the LTrim
thing. It might help you to use the Excel
graphing features and make some scatter plots
of LTRIM vs cell, STRIM vs cell, that kind
of thing. It makes it visually obvious whether
you are uniformly offset, or have some non-
uniform problem. Working from the averages
may have you giving more emphasis to the
most-frequent, but perhaps least-interesting,
regions of operation (like, idling and level
cruise are not too related to under load and
WOT, but you spend more time there). Maybe
this will help some people get a more focused
understanding of what's really driving their
mixture and make a more "surgical" correction.

Or not.

 

2K, you are right, its all me.

The vacuum leak that I was thinking about would be located between the MAF sensor and the combustion chamber, usually around the intake manifold. A vacuum leak located around the intake manifold would allow in un-metered air. The PCM would "see" a lower amount of air and calculate a too short PW for the injectors. The O2 picks up on this and the PCM adjusts the LTFTs until you are back to 14.7:1. Your spark plugs should look good (not lean or not rich) under this situation. If the LTFTs go to its limit and more correction is needed, then you set a SES code.

IF the vacuum leak is in the exhaust system, for example at the header/cylinder head interface, the extra oxygen in the air would fool the O2 sensor into thinking that you have a lean condition. Again here as above, the PCM would increase the LTFTs upward to correct a preceived lean condition. However, you may not actually be lean, and therefore the higher LTFTs would have you running very rich in the combustion chamber, but it might look OK to the O2 sensor. In this case, I would expect the plugs to have alot of black soot on them.

But you have said now that you have descreened the MAF sensor. If no vacuum leak is present, this is for sure the root cause for your high LTFTs. The LTFT values tend to be much higher at idle, then as you go up thru the various fuel cells you will see lower LTFT values. As you go into WOT the LTFT value might be only half of what it is at idle. What you discribed is very typical.

You have too high LTFTs to expect the fuel injector table to correct your situation. Fix your MAF table with LS1Edit. I have written on a good method to do this many times, do a search. Remember, because the LTFT values are different for each fuel cell, you can not mutiply the entire table by a fix value. This will not be good for an automatic car.

But again, if you do not have a heads/cam car, just reinstall the factory MAF as it came from the factory. You dont need the descreened MAF for extra air flow. Then having gone back to the factory MAF, you can let the PCM re-learn and then correct the LTFT values if the WOT LTFT value is above 0%.

 

Maybe I need to check the Pace VV out.. I need to figure out which one would be better and cost effective.. My car will never see 500hp so if I can find a stocker for ~$90 bucks I might pick one up..

Ok, here's a question.. Will the MAF table change on it's own without LS1Edit? Over the driving time of the car to accomdate changes? Such as, will the computer "learn" a certain thing and change the table or do these tables come "set" from the factory? or if i went and pulled the stock tune from my car, should the MAF table look like it would from the factory.. Does that make sense?

I think I have a lead on a stock MAF.. Or do you know if the stock screen can simply be replaced? I am not sure where my MAF screen is nor if I could replace it..

This sounds like a good place to start on fixing this issue..

<small>[ February 27, 2003, 03:38 PM: Message edited by: 2K T/A Driver ]</small>

 

No, the MAF table will never change. All of the "pcm learning" is done thru the STFT and LTFTs, and KR if you will.

Alright, you have LS1Edit, right? You cant fix your MAF if you cut the screen out. So, take my advice and re-calibrate the MAF table. What you should do is to down load from the PCM the stock program. You do this with LS1Edit program software. Save this file as the original stock file. Open this file with LS1Edit, and make some easy change like a fan speed change (or nothing at all) and immediately save the new file under a different name. You do not want to ever alter the stock PCM program that you have saved. You can go back to it as a reference at any time.

So fix your MAF table as a trial with LS1Edit BEFORE you spent any more money on a MAF sensor.

 

I have been following along and I gather DOCX and DOChome are one and the same...... anyway some good advice for us newbies so far DOC..... I am in a similar state as 2K but my LTFTs are only +7+9 after a MAC header install with a stock MAF and internals. I do have EDIT and I am still stuck on which table to work with to get my LTFTs to a 0 or - number. I have the slight puff of black smoke at WOT and lots of soot on my tips on a regular basis but my gas mileage seems okay so I am probably right on the edge. Car will be coming out of storage in 2-3 weeks and I need to be prepared to tune as VIG3200 is going in..... all suggestions with theory/reasoning are appreciated <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />