Little bit on the car:
K16 Hybrids, 5 bar fuel pressure regulator. Running 1.2bar on CA 91oct. GIAC tune.
In short, I have taken the car to the track with a best of 12.2@117mph on a 2.0 60ft. This got me to do a data log where I saw some very interesting things:
-by 4500 rpm the MAF was pegged at 5v
-injectors DC jumped to 120%+
-timing dropped to 3deg adv and slowly climbed to 18deg by redline
-AFR between 11.4-12.3
-IAT climbed by 25C+ over base temp

I am looking to better understand the way the ECU operates, but here is what I believe is happening:
The turbo's are pushing more air than the MAF can handle. This causes the ECU to add as much fuel as possible and retard the timing to protect the motor. The ECU does not have visibility into the air volumes due to the maxed out MAF, and because there is no knock, it slowly adds timing back in. The retarded timing is probably sending flames into the turbo's causing my EGT's to skyrocket and cause my IAT to climb drastically. If my speculations are inaccurate, please let me know?

At this point, if I want to extract the full power of the turbo's and motor, I will need to:
Return to the 3.8bar FPR
Add larger injectors 60lbs
Change to a Hitachi MAF
New Tune for different parts

My hope is that these would:
Get my Injector Duty Cycle down to 80%+/-
MAF voltage becomes measurable by the ECU again

After the above, it looks like I will need to upgrade my IC's to cool IAT.

Thanks for any clarity on my speculations. (I can also provide some Datalogs if people are interested.)

 

you answered yourself all the questions... lol

 

Agreed, looks like most the questions were answered by your research. From what I understand, the 5 bar fpr is a great easy way to get some more fuel to the car, but you're really still limiting yourself by the injectors. The install of injectors is a *****, but the parts for injectors vs 5 bar is only ~400. Considering the cost of all the other mods, what you're leaving on the table, and the added safety of larger injectors, I'd say injectors is really the way to go.



Also, I'd love to see more logs posted somewhere as a rough database or comparison guide. I view them as dyno's, you can't trust them apples to apples, but they do give you some guidelines and can be beneficial to see gains on your own car as you change components.

I came from the Audi world, and we commonly did the 3rd gear logs just like p-car guys do, but then by comparing the delta time vs delta rpm of a few cells at a time you can get a rpm/sec. I.e. acceleration map. It was a pretty good way to see acceleration gains from tune updates, parts updates, or just weather conditions. I'd like to see some rough numbers for the different setups on here, but there just aren't many examples out there.

I know on my car from "stock tune w/ exhaust" to "tuned with exhaust" I went from ~570rpm/sec avg for a 3-6k pull to ~710rpm/sec avg for a 3-6k pull. When I do injectors and billets I'm looking forward to seeing the change again.

I'm always happy to edit down and add the formulas in for anyone willing to share some logs. I know some people don't know what to look for or what to edit down. But once everything is cleaned up / edited down, the logs aren't nearly as scary to try to understand and provide a much better means to see how things improved as parts were changed.

 

That would be a logical progression of add-on parts. Feel free to PM or email me and I can help you get everything squared away.

 

You are asking all the right questions and you are on the right path with your answers. you can put a better fuel pump to increase the fuel supply. I would also go straight to 72lb injectors and skip the 60lb ones.

 

Thank you all for the reply and confirmation that my beliefs on what the ECU is doing is correct.
I do have questions on how much the Wide Band O2 sensors play in adjusting the timing and Inj Duty Cycle to maintain a proper AFR.?
I will also do a leak test, but don't believe I have any significant leaks due the Inj DC being well over 100% and the AFR in the mid 11's-12's.

For those interested I attached a one of my runs. (I know I am logging too many fields for the best visibility, but wanted to confirm suspicions.)

Not that I want to hijack my own thread, but how is the idle with 72lbs injectors, and will I run into a fuel pump issue at WOT and 1.2bar?

 

Hey Shawn, did the new MAF help a bit? Get more mph/less correction?
I think it's time for the next stage and some more fuel. Especially with the cat delete.
Call me anytime

 

We typically recommend the Siemens 60lb injectors. They will give you plenty of headroom and allow for a normal idle.

 

I guess I should provide a bit more detail:
The headers have been "cleaned up" (Ground some of the rough edges and welds for a little better flow). Because of the fire I was sending through the exhaust, I killed my 100cel cats and a couple of weeks ago gutted them. (For those interested, I get a bit faster spool, a lot more turbo whistle, and a deeper lower frequency from the exhaust.

I have tested two MAF's with the second one giving me a bit more visibility to the airflow, but it still pegs at 5v around the same RPM range.

One question I am curious about regarding the setup, but then will most likely answer...

If my turbo's are flowing more air than the MAF can measure, causing my injectors to run at over 100%+, would switching to a Hitachi MAF and retune for that MAF be enough? Aren't the stock injectors and 5bar FPR good enough for 550HP?

That question asked, I have been told the turbo's are good for 650HP+ which might be my problem, and if I have to put in a Hitachi MAF and a new tune, I might as well put in supporting injectors at the same time...

 

Most tunes that make 550+ hp peg the MAF. They do compensate for that. There are many 700hp cars with the stock MAF. If you add fuel you will be good. but at that point the pull kit with the Hitachi runs great.

 

Any pictures of this process? (cleaning up the headers) Just curious as it was something I had considered doing myself/having done. Any part number on new header gasket (if needed). Just seemed like a good simple mod to help things flow better. I've heard markski and others talk about this, and how the stock headers are good for serious power.

Yea, the stock maf pegging out is something that doesn't get talked about a whole lot. But I guess most people aren't asking the tuning companies in depth questions that much (or at least just not posting it up publicly). The MAF swap is the reason most the bigger hp kits make the MAF switch, or the mafless tune that several are running is also pops up as a viable option.

Which hybrid K16's are you running by the way? Just curious.