Yet Another Injector Tuning and MAP Sensor Question

Not too long ago I upgraded my stock GTP injectors to a set of Bosch 42.5's (Part #9202100 / 0280155968). After doing a ton of research I realized that everyone has their different ways to adjust for the new injectors in the tuning software that they feel is best (i.e. "Multiply by this" or "Multiply by that" or "Set the whole table to this"). At this point I've been scratching my head trying to get it right for so long I'm practically going bald here. Attached you will see the stock zzp settings along with the new settings for the new injectors that I've been messing with that seem to running ok. Do they look about right? The only table I adjusted was the Flow Rate vs KPA table.

Also I have all these upgrades listed below and I still have a 1 bar MAP sensor. I am maxing out the map sensor (at least what I'm scanning). Is there a way to adjust the 1 bar map sensor so I don't have to buy a GTP/GS PCM and buy 2 new credits?

As always, thanks for your expertise and time.

Jeremy

If you look at a factory tune for the supercharged GM V6 cars you will see the VE table is set up the same as far as range is concerned. A 2 bar MAP sensor wouldn't be compatable and this is why some of us are very glad the MAF sensor pretty much controls all of the V6 fueling.

If you have the original paperwork from the original 42.5 injectors, they have a lot of info on them that tells you what you use to set the numbers to even from injector to injector, so injector offsets can be used, however, that said, it's not mission critical and suddenly impossible to tune in the new injectors without this info.

In the "old days" I was tuning with PowrTuners and had great experiences using basic math to help me get the proper numbers into the IFR (injector Flow Rate) table. Scanning later on with HPTuners backed up what I already new... that at least on my car and in my case, it was bloody near perfect in terms of a solution.

Let me explain why and then move on to the way this is done in the HPTuners.

I had been tuning my GTP well before the change to 42.5 lb injectors and the fueling part was pretty much perfection with the exception that when I installed the 3.2 pulley, the injectors went static at WOT above 5000 RPM.

Changing the injectors increased the fuel flow in a uniformed manner from idle to up top and for the car to run properly, IN THEORY I would need to lower the amount of fuel used and the extra headroom of the high flowing injectors meant that they never hit the wall and went static... which after changing that one table, is exactly what happened. What also happened is that my entire tune stayed as "locked in" as before I changed the injectors, which supported the methodology as being the correct one.

So, what did I do? Basic math.
42.5 divided by 36 = 1.18055

This obviously means that I increased fuel amounts by ~ 18% by installing these injectors.

In the PowrTuner program, I *lowered* the IFR tables uniformly by 18% and the car's tune came right back into line as if I had done nothing at all... except that I had an increased capacity of fuel available up top (18% more, to be exact!). I went from going static, to not being anywhere near static.

The entire rest of the tune (except for the very top end) remained identical.

Now, the HPTuner app works a bit differently than the now defunct PowrTuner and instead of telling it to reduce flow by a percentage, you need to tell it that at any given kpA value, that it is flowing MORE fuel flow, and therefore, it reduces the amount appropriately.

So, how is this done? Well, a few years ago, I made this small video that shows how.

Enjoy. :)

http://syner-g.no-ip.biz/GTP/_custom...injectors.html

PS... it's done in FLASH.

Finally... injector offset. Since most are missing this info, and we want fueling to be perfect in all cylinders, that's where we do some extra work and drive for a week or so, then check spark plug colour and off set fuwling based on what the plug tells us. To rich, lean out that cylinder by 1%. To lean, add 1% more fuel. Since this is something that in theory never changes, you do this once, then never again... but it may take several iterations before it is perfect.

Quick note... on my 1999 GTP, it needed no offset, each plug was perfect in colour after 10 runs down the track and a month later when I checked again.

I am not going to go through how to check plugs... google it. :)

The MAF issue... I handled it by simply moving to a MAF that had more capacity and used an LQ4 MAF/NorthStar throttle body and then tuned the car appropriately for it. This has more than enough "room" to grow to hit 475-500hp on the dyno.

Firstly I want to give you both a big THANKS for the help. Sometimes I feel so lost with this stuff that I just want to throw in the towel.

Quote:

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If you look at a factory tune for the supercharged GM V6 cars you will see the VE table is set up the same as far as range is concerned. A 2 bar MAP sensor wouldn't be compatable and this is why some of us are very glad the MAF sensor pretty much controls all of the V6 fueling.

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Yeah that's what I thought too that the MAF sensor does the majority of the work when it comes to fueling. Thanks

Quote:

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If you have the original paperwork from the original 42.5 injectors, they have a lot of info on them that tells you what you use to set the numbers to even from injector to injector, so injector offsets can be used, however, that said, it's not mission critical and suddenly impossible to tune in the new injectors without this info.

In the "old days" I was tuning with PowrTuners and had great experiences using basic math to help me get the proper numbers into the IFR (injector Flow Rate) table. Scanning later on with HPTuners backed up what I already new... that at least on my car and in my case, it was bloody near perfect in terms of a solution.

Let me explain why and then move on to the way this is done in the HPTuners.

I had been tuning my GTP well before the change to 42.5 lb injectors and the fueling part was pretty much perfection with the exception that when I installed the 3.2 pulley, the injectors went static at WOT above 5000 RPM.

Changing the injectors increased the fuel flow in a uniformed manner from idle to up top and for the car to run properly, IN THEORY I would need to lower the amount of fuel used and the extra headroom of the high flowing injectors meant that they never hit the wall and went static... which after changing that one table, is exactly what happened. What also happened is that my entire tune stayed as "locked in" as before I changed the injectors, which supported the methodology as being the correct one.

So, what did I do? Basic math.
42.5 divided by 36 = 1.18055

This obviously means that I increased fuel amounts by ~ 18% by installing these injectors.

In the PowrTuner program, I *lowered* the IFR tables uniformly by 18% and the car's tune came right back into line as if I had done nothing at all... except that I had an increased capacity of fuel available up top (18% more, to be exact!). I went from going static, to not being anywhere near static.

The entire rest of the tune (except for the very top end) remained identical.

Now, the HPTuner app works a bit differently than the now defunct PowrTuner and instead of telling it to reduce flow by a percentage, you need to tell it that at any given kpA value, that it is flowing MORE fuel flow, and therefore, it reduces the amount appropriately.

So, how is this done? Well, a few years ago, I made this small video that shows how.

Enjoy.

http://syner-g.no-ip.biz/GTP/_custom...injectors.html

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Two words "Mind Blown!!" :worship:. Hope you don't mind but I have bookmarked your website. Thank you so much for your time and expertise.

Quote:

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Finally... injector offset. Since most are missing this info, and we want fueling to be perfect in all cylinders, that's where we do some extra work and drive for a week or so, then check spark plug colour and off set fuwling based on what the plug tells us. To rich, lean out that cylinder by 1%. To lean, add 1% more fuel. Since this is something that in theory never changes, you do this once, then never again... but it may take several iterations before it is perfect.

Quick note... on my 1999 GTP, it needed no offset, each plug was perfect in colour after 10 runs down the track and a month later when I checked again.

I am not going to go through how to check plugs... google it.

The MAF issue... I handled it by simply moving to a MAF that had more capacity and used an LQ4 MAF/NorthStar throttle body and then tuned the car appropriately for it. This has more than enough "room" to grow to hit 475-500hp on the dyno.

---

I have the same setup and just used an LQ4 MAF table and adjusted from there. Well not really since I need to dial in the new injectors before moving on to MAF tuning.

Thanks again

Jeremy