tuning....fuel

ok, so anyone that has a DHP tuner and some mods done...(headers and rockers/cam at least)
how much % did you need to tweak the MAF numbers to add more fuel?

after installing the headers, Ive had to add 2-3% in the lower cruise/idle frequencies and 5% or so in the middle/upper MAF frequencies. I am getting my fuel trims locking at zero FINALLY while in PE mode.

does this sound right? Seems like im adding alot more fuel. And if I take the car out at night (which I usually do) and its cold, it seems my LTFT numbers still like to peak into the lean numbers.

This is a horrible thing to say because every car is different, but for most modded cars I find I add 8%-10% over 7500 Hz.

On my car I spent a lot of time tuning VE before I started tuning MAF, so I didn't need many changes on the MAF tune except at the higher levels.

If you have less than 5% correction, don't kill yourself trying to perfect it. Fuel requirements are constantly changing so it will never be 'perfect'.

I haven't tuned VE, and I needed fairly large adjustments to MAFF in the upper frequencies. 10% easy on the 3.2" pulley. Didn't seem to hurt anything, but the dyno run proved I was a bit rich with 10:1 A/F, so wasn't making as much power in theory. I picked up 8 hp by leaning it out, but I can not drive with that tune on the road... KR city.

I want to do a VE tune as soon as I learn the best way.

I'm bad.. I started tuning VE and then didn't do the maf.

you probably didn't need to after a good VE tune

ive never done the VE tune, only because MAF tuning is " recommended" and tweaking it gets the results I want.

I haven't even started tuning in the 9K up range since I was still getting alot of KR before. I think I can still run my 3.25" pulley and get no more than 2* of KR if I get the fuel tuning right.

I need to adjust my timing too (bump it up), but do I need to be at zero KR before doing so?

Both VE and MAF are "recommended", depending on who you talk to. Many from the Ford side are more comfortable tuning MAF only, because VE is a GM thing, or at least they used it first.

If you're not able to tune out KR under 9k MAFF, you are probably running too small a pulley for your mods, or else something else isn't right.

Andvancing the timing will make any KR you have worse. You should only advance it if you are at zero KR 100% of the time, imo.

u could order an Intense PCM
I have a stage 3-1/2 setup, heads, cam, headers, LS1 throttle body, ls6 MAF, a GEN V s/c, and a 3" pulley, but i havent driven it around yet with the 3" pulley, but I ordered a custom PCM and the VE tables were already modified. So all i really had to do was fuck around with the MAF and I havent had any knock yet. Long and short terms are still out of wack but theres alot more tuning that needs to be done. Thank god theres a dyno shop a 1/2 mile away.

There is no way anyone can pre-tune a VE table or MAF, every different combination of mods needs a slightly different table. Maybe they put in a VE table they've used before but I wouldn't trust it.

One of my early mods was an Intense PCM and it didn't have any VE or MAF tuning that I'm aware of, they matched the stock tables that I saw.

I'm in agreement with Derek on the predone VE changes. Not that I've ever heard of.

And I had Intense setup my pcm for S1X, N* etc etc.

AA wrote:

Both VE and MAF are "recommended", depending on who you talk to. Many from the Ford side are more comfortable tuning MAF only, because VE is a GM thing, or at least they used it first.

If you're not able to tune out KR under 9k MAFF, you are probably running too small a pulley for your mods, or else something else isn't right.

Andvancing the timing will make any KR you have worse. You should only advance it if you are at zero KR 100% of the time, imo.

Im not getting KR under 9k, I never see KR unless under WOT and alot of boost, even when my fuel tuning were rather lean. So thats certainly not a problem. Even then I peaked at 5* KR.

I'll do a couple WOT runs and see where the KR is at.

deekster_caddy wrote:

There is no way anyone can pre-tune a VE table or MAF, every different combination of mods needs a slightly different table. Maybe they put in a VE table they've used before but I wouldn't trust it.

One of my early mods was an Intense PCM and it didn't have any VE or MAF tuning that I'm aware of, they matched the stock tables that I saw.

You dont have barely shit done to ur car!!! The true VE efficiancy changes with valve, cam, and head work, not with a k&n and muffler.

Try and find some better place than INtense to find a pretuned PCM and if you have your own tuning software, then you will appreciate what they do when u see it.

Every car can benefit from a good tune.

The programming from the factory is desiged to work well in all climates around the world. When you tune specifically for where the car is driven, it can and will run much better.

Also the factory tune is an average set of numbers for what is supposed to be right for your engine, but every engine is slightly different due to a combination of variables. I agree tuning a stock engine is worthwhile. It lets you get closer to the exact needs of your specific engine. The shift settings alone are well worth changing in any car.

97rivman wrote:

deekster_caddy wrote:

There is no way anyone can pre-tune a VE table or MAF, every different combination of mods needs a slightly different table. Maybe they put in a VE table they've used before but I wouldn't trust it.

One of my early mods was an Intense PCM and it didn't have any VE or MAF tuning that I'm aware of, they matched the stock tables that I saw.

You dont have barely shit done to ur car!!! The true VE efficiancy changes with valve, cam, and head work, not with a k&n and muffler.

Try and find some better place than INtense to find a pretuned PCM and if you have your own tuning software, then you will appreciate what they do when u see it.

I'm sorry, I feel like I've done quite a bit to my car. 1.9 rockers are kind of like a different cam, although granted it's not as good as a cam it definitely changes efficiency all over the place by changing the valve lift. I learned to tune engines with VE only, on a speed pro system that has no MAF, on an engine nobody had ever fuel injected to my knowledge, we built the entire VE table from scratch. So I started tuning this car by unplugging the MAF and VE tuning. I spent months doing it and my 'tuned' VE table is VERY different looking the the VE table that GM ships you, and my car runs very well without the MAF, which it did NOT do when I started. Even though I haven't done shit to my car. Changing pulleys DOES change the VE table, even if slight. _Every_ airflow mod makes changes to the volumetric efficieny of the engine. Combine 4 mods like headers, rockers, pulley and fwi and you will need a different VE table than a stock engine.

I don't think anybody can pre-tune a VE table unless they have the exact same engine in the same weight car with the same fwi, exhaust, mods and gearing as you have. Even then some engines were built differently, sometimes gaskets weren't aligned properly from the factory causing airflow issues, the same camshaft might be degreed differently, they can't know about that stuff in advance...

I'll grant you that they can take some good guesses and get close, but to have an accurate VE table takes time and experimenting with a tuner _in your vehicle_.

The PCM I bought from Intense had a stock VE table. Maybe they change the VE table for you if you tell them you have a cam and xxx mods, but that wasn't an option when I bought mine. I'm pretty sure they only thing they changed were the timing and transmission tables. I'll admit that was a few years ago now and since then maybe they have changed things.

My car is not an extreme setup, I haven't ported my heads yet and I haven't installed a cam yet. I haven't slapped on a GenV or Turbo yet. I need to drive my car every day, pay for my mortgage and put away money for my children's education and my retirement. These realities have given me a budget for my car that hasn't allowed those things yet.

I have spent a lot of time working on cars, more than 20 years in fact. I have built many engines, always building with street/strip/daily drivability, power, efficiency and reliability in mind. My builds are usually for commuter cars that can go fast too. So my car is a high 13s/low 14s car and not an 11 second car, well that's the way it is. If you think I don't know what I'm talking about when it comes to tuning that's fine for you but I'm standing by my original opinion. I don't believe you can pre-VE tune for somebody else's custom setup.

update:
I added 4% into my 9k up ranges, and did a WOT run.

The car still sometimes locks in PE at 0.7-1.5 but half the time it locks in at zero. I did a WOT run (but feathered the throttle on takeoff) and saw max blip KR of 2* and only during a shift from 2-3.
got a 2nd and 3rd gear scratch this time.

I think after the intake/ported SC fix (and cleaning up the injectors), I will have zero knock with the 3.25" and can start bumping up timing.

anyone know how to bump up timing correctly?

dreww, just curious if you've read the DHP forums, and seen how to disable torque management? That made another big difference for me. The computer pulls timing for 'torque abuse' (anytime you stomp on it) but you can change it's effect to -nil-.

You and I are basically running the same setup, headers, 1.9 rockers, CAI/FWI, 42.5s, 3.2... Except you have a '96 to my '98 so the transmission tables wouldn't be the same.

I can send you my .bin if you want to look it over. I also VE tuned my engine for cruise and mid (but not WOT yet), you can have a look at how different my VE table is from the stock VE table which is pretty soft.

Also keep in mind there is no fuel trim while in PE mode.

I'm still a bit uncomfortable with the timing tables. I'm used to seeing a timing table based on RPM/TPS, this table is a bit of a mystery to me still. I'm not comfortable but there is a utility you can download from the DHP forums that can recommend a timing table based on your scan...

deekster_caddy wrote:

dreww, just curious if you've read the DHP forums, and seen how to disable torque management? That made another big difference for me. The computer pulls timing for 'torque abuse' (anytime you stomp on it) but you can change it's effect to -nil-.

I can send you my .bin if you want to look it over. I also VE tuned my engine for cruise and mid (but not WOT yet), you can have a look at how different my VE table is from the stock VE table which is pretty soft.

Also keep in mind there is no fuel trim while in PE mode.

I'm still a bit uncomfortable with the timing tables. I'm used to seeing a timing table based on RPM/TPS, this table is a bit of a mystery to me still. I'm not comfortable but there is a utility you can download from the DHP forums that can recommend a timing table based on your scan...

yea, Im on the DHP forums. One of the first things I did was disable all torque management. And yes, that made a noticeable difference. One major difference in our mods is I dont have my EGR anymore. That tends to affect timing quite a bit, or so I hear.

I do know there are differences in the DHP software for 96 and 97+ models, the primary on being the different transmissions. But I thing my IFR chart is difference along with my VE chart.

I know there is not fuel trim while in PE mode, but if it locks in a little bit lean (which it tends to do), I know that I need to tune in more fuel in the mid MAF frequency ranges. But truthfully, after I reached the 9k MAF range where I programmed in more fuel, KR was pretty much gone.