I've been working on tuning my truck with HPtuners for far too long and I keep getting advice from different people online. Right now it seems to be running pretty good but I want to know what is the best way to tune it from a stock PCM. Step by step with 1bar MAP and a wideband. Thanks

definatly get a wideband. A 2 bar would be great but its not a viable option for everyone ($). Of coarse you can tune it with a 2 bar just takes a little work with the tables and cutting resolution in half.

wish I could help you out more, seems like you've learned alot since you picked up your HPTuners.

hows your AFR and KR ?

the KR is basically gone. I'm having issues with my wideband so i'm not sure about the a/f ratio. I'm not sure where it should be at part throttle or how to make part throttle adjustments to the a/f. I know wot should be 11/7:1 and I know to adjust my PE to do that.

Thats a good WOT AFR for a boosted vehicle. AFR at part throttle should be at 14.7:1. You should try to get your Long terms as close to zero as possible. This will keep you right at 14.7:1 and help you get better MPG. YOu can do most of this in the VE tables. If you see a positive LT value then you should be adding more fuel by adjusting the VE table and vise versa. IF your LT's are right on meaning your ve table is golden you should be at about 1.23-1.245 for PE to get your 11.7:1 AFR.

what about my ifr table? some guys say it should be flat accross the board at 41.67. Others say i should scale the table and adjust it to get my ltft to 0. I tried it at 41.67 for my 42lb injectors and my ltft were all over the place.

True some scaling should be done as at differnet fuel pressures your IFR will infact change some. Your 2002 will have a difference infuel pressure across the board because of the regulator. Anything ratical should not have to be done here though. Most of your work will be in the VE table I am sure. It will be a matter of figuring out what fule pressure you run at diffent manifold pressure values. Then figuring out injector scalling as nessisary. I would opt to do it in the VE table though.

For your IFR table, just put in the actual IFR of your injectors at your fuel pressure (most injectors are rated at 43.5psi and our trucks run at 58psi). Then adjust your VE table to get you negative (really easy to do once your wbo2 problems are ironed out -- using speed density / "mafless" tuning). From there move on to the WOT tuning -- it will change depending on the previous two (same with idle most likely).

The reason you LTFTs were super weird is that those injectors are most likely 42ft/lb at 43.5psi. 58psi makes them closer to 48.5 lb/hr injectors.

For your IFR table, just put in the actual IFR of your injectors at your fuel pressure (most injectors are rated at 43.5psi and our trucks run at 58psi). Then adjust your VE table to get you negative (really easy to do once your wbo2 problems are ironed out -- using speed density / "mafless" tuning). From there move on to the WOT tuning -- it will change depending on the previous two (same with idle most likely).

The reason you LTFTs were super weird is that those injectors are most likely 42ft/lb at 43.5psi. 58psi makes them closer to 48.5 lb/hr injectors.

ok, so what should i set them at in the IFR table? i idle at 48psi and goes up to over 60, can't remember exactly how high.

what injectors are they. if its the marine injectors they are 43.82@58psi.
what i did on mine was take the value which was the highest and subtract 43.82 and the number i got i added to the whole table. this may not be exact but it worked great. funny thing is the first time i did this i tried to adjust my ltft and everything kept geting richer and richer so i put the whole fuel side of things back to stock then just put in my injector size as above and snakeeater pull a little off the whole ve table and tuned some timming now my fuel mileage is back way up. my turbo isn't on yet so not sure about the boost side of things yet. but i'm working on it.

ok, so what should i set them at in the IFR table? i idle at 48psi and goes up to over 60, can't remember exactly how high.


Is there one number in every cell of the IFR or are they different? In other words, does your truck have a boost referenced regulator on the driver's side fuel rail?

You also need to find out what those injectors are rated at initially -- if the multec II stubbys, they are 43lb/hr at 43.5psi. The next step is to find out the rating for your truck -- I'm just not sure about the 02's, but it's probably a 4bar (58psi) setup.

Ok, my truck does have the vacuum referenced regulator on the driver's side fuel rail. Right now, i have different numbers in each ifr cell. I used a spreadsheet I got from a guy on ls1tech named darkblueTA. My ltrims look great using those numbers. My injectors are 8.1L 42lb marine injectors that I got from Arizona speed i think.

All I know is, my Nelson tune had them set at 5.15 accross the board, and someone from HPtuners said to set them at 5.25 across the board. I have no problem doing this, but, when i do my ltrims are totally whacked and adjusting the VE doesn't work as far as I can tell.

If you have a vac ref'd regulator, you should have the same value in every cell and it should be the actual flow rate of your injectors at 58psi. If you populate that table with multiple values, you are using GMs work around for *not* having a vac ref'd regulator (e.g. providing different flow rates at different vacuum readings -- which is what the VRR does).

If you are running a tune with non-vac ref'd IFR values, and then switch, your VE will be waaay off. To adjust your VE, you need to do SD tuning -- otherwise, you are fighting the MAF the whole time.


An easy way to tell for sure is to look at your stock tune. If it has a single value, your performance tune should have a single value.

i haven't done so yet, but, it was suggested to me that i should cap off the vacuum reference. bad idea?


i think i'm gonna put a stock tune back in and start all over again.

Ok, my truck does have the vacuum referenced regulator on the driver's side fuel rail. Right now, i have different numbers in each ifr cell. I used a spreadsheet I got from a guy on ls1tech named darkblueTA. My ltrims look great using those numbers. My injectors are 8.1L 42lb marine injectors that I got from Arizona speed i think.

All I know is, my Nelson tune had them set at 5.15 accross the board, and someone from HPtuners said to set them at 5.25 across the board. I have no problem doing this, but, when i do my ltrims are totally whacked and adjusting the VE doesn't work as far as I can tell.

the reason for not being able to adjust the whacky trims with the ve is because your still using a maf, if you adjust the maf table once the ifr is set you will be able to line the trims up

the reason for not being able to adjust the whacky trims with the ve is because your still using a maf, if you adjust the maf table once the ifr is set you will be able to line the trims up

if you want to tune trims with the ve you need to be in SD

i tuned a complety diferent way. didn't touch the ve table till the very end.

put in the ifr number you think it correct and go for a spin. check your ltrims at idle and part throttle. if they are positive in most places adjust the ifr till they are slightly negative.

once your ltrims are slighlty negative then use your wideband to adjust for WOT fueling. adjust with the PE vs RPM table.

i dont see the point in messing with the ve table unless you are having some kind of driveabily problems. just let the maf do it's job. with the whipple i never had any problems tuning this way. once i got the turbo on there and started turning it up things got kind of wierd and i then had to play with the ve table to get the throttle transitions smooth.

i am not saying the SD way is wrong, just not how i did it and i dont really understand it. if you unhook the maf be careful with boost, infact i would keep it out of boost all together, the 1 bar map can not see boost and will not add fuel for it.

so how much boost can the maf see before it maxes out?

i tuned a complety diferent way. didn't touch the ve table till the very end.

put in the ifr number you think it correct and go for a spin. check your ltrims at idle and part throttle. if they are positive in most places adjust the ifr till they are slightly negative.

once your ltrims are slighlty negative then use your wideband to adjust for WOT fueling. adjust with the PE vs RPM table.

i dont see the point in messing with the ve table unless you are having some kind of driveabily problems. just let the maf do it's job. with the whipple i never had any problems tuning this way. once i got the turbo on there and started turning it up things got kind of wierd and i then had to play with the ve table to get the throttle transitions smooth.

i am not saying the SD way is wrong, just not how i did it and i dont really understand it. if you unhook the maf be careful with boost, infact i would keep it out of boost all together, the 1 bar map can not see boost and will not add fuel for it.


Ok, this is what I was told to do by darkblueta. I was feeling pretty good about tuning this way until i started reading that it was a horrible idea to mess with the ifr table. I think i'm gonna try both ways and see which works best for me. Trying to stay out of boost is not easy, wow.

I noticed tonight that my advance is totally whacked too. Looking at my max and min in the histogram, they are not even close in some cells. Like 0 min and 35 max. What could be pulling that much timing? No KR.

Also, after doing a WOT run, my truck runs like shit. Almost always. Is there some sort of abuse mode or something that it could be falling into? My wideband works great until after I go WOT. Then it reads 11.25 in every cell. WHY? I was told it's the CAT over temp. NOPE, i have it disabled.

chances are your wideband is bottomed out. running to rich that it is reading as rich as it can. dont worry about that yet. get your ltrims slightly negative at idle and part throttle, then make sure they goto 0 at wot. then start pulling fuel till you get it up to 11.8 or so.

the stock maf isn't limited by boost but rather by airflow. can't remember when i maxed mine out but with a 4.8 i would guess 15+psi before you start bumping the limit. just bumping the limit isn't a big deal either, it is when you max it out at 4000rpm you have tuning problems.

so i should be good i guess then. thanks.

i haven't done so yet, but, it was suggested to me that i should cap off the vacuum reference. bad idea?


i think i'm gonna put a stock tune back in and start all over again.


For boost, you want a boost referenced regulator, IMO. I guess I can see this method (capping the ref line) for really really huge cams were the vacuum is 'not good' ?

I didn't like the IFR method because it is just tricking the tune into running in a reasonable manner -- that method just tells the computer that the injectors are a different size than what they really are in order to match the inaccurate VE and relying on the MAF to make up for the problems that generates. But, there are points in the rpm vs. MAP range where the *VE* is ignored (like over 4000 rpm, and at 400, 800, 1200 rpms).

I dug into SD tuning because I was ditching the MAF sooner or later anyway and was tired of chasing it around trying to nail the VE table :)

These days, SD tuning is super easy. Both EFI Live and HPT do some kind of automation in the process that really makes it as easy as setting up to run open loop (assuming you have wbo2), logging, and right clicking.

i know the maf is not ignored above 4000rpm and i am 99.9% sure it isn't ignored in the lower rpms. if it was ignored above 4000rpm anyone with boost and a stock map would run blindly lean and that is not the case.

and the debate continues. lol

i'd just pay someone to tune it but can't find anyone locally who would know how.

and the debate continues. lol

i'd just pay someone to tune it but can't find anyone locally who would know how.


you have a wideband right? difinately learn to tune it yourself, with a wideband it is easy. i actualy enjoy the tuning part of my truck.

i know the maf is not ignored above 4000rpm and i am 99.9% sure it isn't ignored in the lower rpms. if it was ignored above 4000rpm anyone with boost and a stock map would run blindly lean and that is not the case.

VE is ignored in both of those situations. Well, to be accurate, the low rpm is mainly MAF with the small chance that the SD calc will impact the airflow, but > 4000 there is no SD calc used.

Oh and the RPM ranges are dependent on whether you've changed the MAP & RPM trim range or not (then use those values for the RPM thresholds).

That's all well and good if your MAF has a chance in hell of reading accurately. Otherwise, you're right back to trying to trick the truck into running correctly.


Edit: LOL I *must* stop posting it at work with 4 people talking to me. I wrote MAF in my original post instead of VE...

if it was ignored above 4000rpm anyone with boost and a stock map would run blindly lean and that is not the case.


That's only true if you don't create an accurate VE table to base the calculations on-- I ran significant boost (12psi) with an SD tune on the stock map for months with no trouble. That's one of the main reasons for doing an SD tune -- if your MAF fails (or if the PCM *thinks* it fails) you still have a chance in hell of running enough fuel not to blow up.

All the MAF does is give a reading for airmass into the engine. So does the VE table. Having a grossly inaccurate MAF (because its being maxed) and a grossly inaccurate VE table means the PCM has no idea how much air you are flowing and you have to trick it into giving enough fuel by using a really weird PE value (like 9 AFR when you want 12.5 *made up numbers!!*). Bear in mind that the MAF is inaccurate on it's face (even when its not maxed) by either +/- 5% or +/- 10% depending on who you ask.

Actually, anyone on significant boost (i.e. maxing the MAF) and the stock MAF is running blindly lean and relying on PE (and an exagerated PE to boot -- which is exactly why wbo2s are so vital to setting the PE for a MAF) to keep the motor from going boom.

DanaliHD-

Some info from the EFILive site on the returnless vs. return (and vac ref'd regulator) issue:


The IFR table tells the PCM how much fuel mass the injector flows as a function of vacuum (i.e. BARO - MAP).

Injector flow rate depends on the pressure difference accross the injector: on one side of the injector there is manifold pressure (MAP), and
on the other side is [constant] fuel pressure plus atmospheric pressure (since fuel pressure is measured relative to atmospheric pressure);
i.e. diff = FP + BARO - MAP, where FP = constant

At WOT, injector flow rate is less (MAP is high), and to spray a specific mass of fuel, the PCM needs to keep the injectors open longer;
At idle, injector flow rate is more (MAP is low), and to spray a specific mass of fuel, the PCM needs to keep the injectors open shorter;
i.e. time(s) = mass(g) / flow_rate(g/s)

Since the pressure regulator is not MAP referenced (in our case, "returnless system"), the PCM uses the IFR table to compensate
for the variation in injector flow rate caused by the variation of MAP;

But, if the pressure regulator were MAP referenced, the regulator would increase fuel pressure as MAP increased, causing the pressure
difference across an injector to always be constant regardless of MAP variation, and in this case the IFR table would be flat with no slope;
i.e. diff = FP + BARO - MAP, where FP = constant + MAP, so diff = constant + BARO



The IFR table is simply the electronic equivalent of a vacuum line running between the intake manifold and the pressure regulator. Trucks have a vacuum referenced pressure regulator so the IFR table is a straight line.



Because the pressue reg is referenced to manifold vac this is what happens.
Lets say you have a fuel rail pressure of 350kPa.
Manifold pressure is 70kPa, the injector pressure will be 420kPa.
OR
Lets say you have a fuel rail pressure of 350kPa.
Manifold pressure is 50kPa, the injector pressure will be 400kPa.

So therefore the table compensates for less pressure at the injector due to manifold vac.

Note: Return systems do not need this table.

Cheers,
Ross



If you connect the vacuum line to the regulator (MAP referencing),
then the regulator will vary fuel pressure as the vacuum changes such
that there'll always be a constant pressure difference across the injectors
(i.e. the injectors will have constant flow rate regardless of MAP value).
[MAP referencing cancels out any MAP influence on the pressure difference across an injector].

In this case, the IFR table must be flat instead of sloped
(you don't want the PCM to adjust the flow rate in this case).


So regardless of what you decide to do on the SD vs. MAF thing (and as long as your boost is going to be low I'd keep the MAF), I'd go back to a linear table. If you don't want to do SD, I would personally adjust the LTFTs using the MAF table and keeping the IFRs at their actual values rather than adjusting the IFRs since the airflow is what changed and since LTFTs measure how out of whack the VE or the MAF is, and so the PCM knows the size of the injectors and can perform its calcs with accurate info, but either one will work with enough blood sweat and tears.

Eric, i am concered that people who read this thread are going to get confused and be afraid to even try their own tuning. i am confused trying to understand what you are saying most of the time. it seems to me you are making things more dificult than they need to be. some of the parts of what you are saying that i do understand are not correct and that makes me wonder about the rest of what you are saying.

it is my understanding that there is no way to tune with the stock map and SD tuning, i tried not running the maf and no matter what numbers i put in the ve table i could not get enough fuel at wot.

hp tuners and the 2 bar set up is completely new to me and opens up a whole new tuning world that i have no experience with but i know how to tune for a stock map and boost right up till the maf is excessivly maxed out.

adjusting the ifr a little till the ltrims are correct is not a bad thing to do. there are things like injector offset and probably other things that we do not have acurate numbers for so a slight adjusment to the ifr to get the ltrims where you want them is no big deal.

from there you can either mess with the PE vs rpm table or mess with the maf table. either way you will get the fuel you need when you need it. the stock o2's and ltrims will take care of any minor fueling adjustments, thats what they are there for.

Eric, i am concered that people who read this thread are going to get confused and be afraid to even try their own tuning. i am confused trying to understand what you are saying most of the time. it seems to me you are making things more dificult than they need to be. some of the parts of what you are saying that i do understand are not correct and that makes me wonder about the rest of what you are saying.


Give me an example of what I've said that's wrong (besides where I started one sentence and finished it with another up above :) which I corrected).

If I'm confused on something call me on it. You should know by now that if you're right and show me why, I'm the first to admit I was wrong about it.

Since I did 100% of my own tuning, and since our initial HP numbers are pretty close to same (I lump my better heads against your better turbo and think the rest is pretty equivalent), I think my method stands on its own just as yours does.

There is no doubt that doing an SD tune requires more understanding of the PCM and what it's doing, and has a steeper learning curve. There is also no doubt that plenty of folks have gotten along without it for a long time just by doing whatever someone on the forums told them to do.

Dan's initial question though is the prefect example of why one-size-fits-all-apply-this-spread-sheet tuning doesn't always work.


it is my understanding that there is no way to tune with the stock map and SD tuning, i tried not running the maf and no matter what numbers i put in the ve table i could not get enough fuel at wot.


I did it. I know of several others who did it as well. We had the benefit of using a whole different method than you did, Jim, and a method that you admit you don't understand.

All you need to do is make the 105kpa cells rich enough (and have the fuel pump and injectors to make it work - but thats true of MAF or MAFless) for your max boost and fine tune with the PE. Those are the cells you'll be in all the time you're under boost, so you have to run richer for lower boost than you absolutely need, but there's aboslutely no reason I know of why you can't do it. I'm not running a MAF now (although I recently added a 2 bar MAP) and haven't for about 10 months. Most of my tuning for the turbo has been SD and a 1 bar map.


hp tuners and the 2 bar set up is completely new to me and opens up a whole new tuning world that i have no experience with but i know how to tune for a stock map and boost right up till the maf is excessivly maxed out.

adjusting the ifr a little till the ltrims are correct is not a bad thing to do. there are things like injector offset and probably other things that we do not have acurate numbers for so a slight adjusment to the ifr to get the ltrims where you want them is no big deal.


I did say this would work and didn't say it's bad. It's just tricking the PCM instead of addressing where the inaccuracy of the tune is. You can adjust the MAF table the same way you've always adjusted the IFR table with identical results. I've done both.

What I think *is* bad is using any method you don't understand. Whatever method you want to use, you should know what its doing and why it does it, IMO.


from there you can either mess with the PE vs rpm table or mess with the maf table. either way you will get the fuel you need when you need it. the stock o2's and ltrims will take care of any minor fueling adjustments, thats what they are there for.

True, stock o2s and ltrims will take care of minor fuel adjustments around your switch point while you are in closed loop... Neither one is super at WOT and relying on either to do WOT tuning is probably a bad idea (although my first tunes did both).

As I said above - ltrims are a measure of inaccuracy in the airmass calc. You can either add more/less fuel and make that match the airmass calc or correct the inputs to the airmass calc (i.e. add more/less measured air reported). I don't see how that's confusing.

(Oh btw, I switched to EFI Live for the 2bar :))