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As mentioned in pm AFR's are too rich and too soon (junior!) for my tastes. Suspect that's why your FF 640s are seeing 90% injector duty cycle at 10psi.
Get that knock sensor properly set up as a matter of urgency. It'll save your motor.
Hey, thanks again for all of the information in the PMs! I'll do back to back VD pulls and target a slightly leaner AFR in boost to check if I gain anything.
I finally have access to my VD plots you were asking about. I'll also toss in the data log of the VD pull showing the 90% duty cycle.
In an attempt to bring my mass following (ha!) in here up to date. The car is currently running 10 psi tapering to just a hair over 11 psi at redline. When looking through the VD datalogs, I noticed my FF640s are touching 90% duty cycle. According to others on here, that should put me close to 300hp. The car feels great but not that great. VD puts me at a somewhat puny 225hp. Somethings funky here.
I've checked the Barometric correction and it's not affecting it. I also don't believe the problem to be fuel pump related. If I command more fuel in the top end my AFRs change accordingly. Allofit suggested I check that my fuel pressure and injector dead times are input correctly in TS. I'm using the stock NA6 FPR so it should be 43.5 psi. TS is showing 42.9. I can't see that small difference making a huge impact. The injector dead times were input with data straight from Flowforce. So I'm still at a loss here. I'll try changing the fuel pressure from 42.9 to 43.5 to see if there's a difference and report back.
In the meantime, here's an updated 3rd gear VD pull and the associated datalog. I'll get off my *** and install the knock sensor real soon I promise!
Edit - Before anyone comments, I fixed that 11psi spike on the initial spool-up. The VD plot shows me hitting 11.8 AFR towards the top end at 10 psi. Nowadays I'm consistently hitting 11.5 AFR.
Your VE table makes a pretty big jump in the 180kpa row as you move from the 6100rpm cell to the 7000rpm cell. That's where your injector duty cycle shifts from 80% to 92% in the transition between those cells.
Expect the general shape of your VE table to be similar to the shape of the engine's torque curve. By which I mean it will start low, increase and peak, and then begin dropping as rpm increases.
My VVT motor and tune has the VE table numbers level off around 6000-6500rpm and then start falling beyond that. Your VE table numbers are rising exponentially well beyond your engine's torque peak as shown in the Virtual Dyno plot.
And I still think a target AFR of 11.5 is too rich for just 180kpa!
I've had a look through your log and tune again........
I apologize, I should have uploaded an updated version of my tune with that datalog earlier. The tune and subsequent VE table you are referring to are pretty out of date. I think I was only on wastegate at the time.
Last night after work I took the car out for back to back VD pulls. The first pull was with my current target of 11.5 AFR in boost and the 2nd pull was targeting 11.8. As you can see, there is a noticeable gain however the 2nd pull peaked at 12 psi vs 11.5psi from the first run. /shrug
I also adjusted the fuel pump pressure in TS from 42.9 to 43.5 but no noticeable difference was made. The duty cycle on the FF640s is still in the 90s at redline at only ~225 hp. I'm still stumped on this one.
Both pulls were taken within 10 minutes of each other on the same stretch of road in the same direction. Side note, I'm not concerned with the hp/tq numbers. I had my girlfriend in the car with me and I wasn't about to ask what her weight was.
Current tune and datalogs of both pulls are below.
Since NB2 has a higher pressure system (60psi vs 43), your input of injector flow at the req fuel table is wrong. Should be in the 720's if I'm not mistaken.
But that still doesn't account for such high injector duty. It should be in the 30s or 40s in your case.
Also I noticed your alternator control is set to "off", while MS should control it to the best of my knowledge.
Allofit suggested I check that my fuel pressure and injector dead times are input correctly in TS. I'm using the stock NA6 FPR so it should be 43.5 psi.
Can we have some more details about your '91 FPR setup? Are you using a 1999-2000 fuel rail with it?
Originally Posted by curly
Your fuel pressure is probably tanking at higher RPM. Hook up a fuel pressure gauge and go for a drive.
Also I noticed your alternator control is set to "off", while MS should control it to the best of my knowledge.
I'm using an NA8 alternator so voltage regulation is handled by the alternator.
Originally Posted by curly
Your fuel pressure is probably tanking at higher RPM. Hook up a fuel pressure gauge and go for a drive.
That's a very good thought, I'll see if I can find a pressure gauge locally. I'm assuming If I'm losing fuel pressure this would point to a bad pump, correct?
Originally Posted by allofit
Can we have some more details about your '91 FPR setup? Are you using a 1999-2000 fuel rail with it?
Absolutely. Since I'm NA VVT I'm using a 99'-00' fuel rail with the stock NA6 FPR flipped upside down. Exactly how It's outlined in the VVT megathread.
On the topic of fuel pumps, I hear DW100 pumps are fine but DW200 may overwhelm the FPR. The 200 seems to be more common than the 100, however. I'm wanting to push the car towards the 300hp number in the future. Would the DW100 still handle that power level? The current fuel pump in the car may be the same one that rolled off the showroom floor. I may order up a new one anyway. I'm just trying to decide which of these two would be best for my long-term goals.
You maxed the fuel pump. It looks the same as "maxed out injectors" unless you know what you are looking at.
Test it this way: Back fuel in your 210kpa row off by ~5% and do a single pull. If AFRs don't change, back it off by another 5%. If AFRs still haven't changed, but your DC% has dropped by a bunch, then the fuel pump is maxed out.
Thanks for the link, I actually happened upon this when I first researched my issue. I figured since my AFRs in boost reacted accordingly to a change in commanded fuel, I could rule this out. On the same coin, a drop in fuel pressure in the top end resulting in an increase in injector duty cycle to compensate makes perfect sense to me. A DW200 will be here sometime next week!
I'm hoping to get out to the garage tomorrow to install my 2nd catch can and finally wire up the OEM knock sensor.
Thanks for the link, I actually happened upon this when I first researched my issue. I figured since my AFRs in boost reacted accordingly to a change in commanded fuel, I could rule this out. On the same coin, a drop in fuel pressure in the top end resulting in an increase in injector duty cycle to compensate makes perfect sense to me. A DW200 will be here sometime next week!
I'm hoping to get out to the garage tomorrow to install my 2nd catch can and finally wire up the OEM knock sensor.
On paper, the oem pump is just about sufficient, but after 30 years of wear and tear, they often don't flow quite enough and it's better to upgrade. DW200 is a good choice.
If you look at your logs, you go from ~70% injector duty cycle at peak torque of ~5700rpm to over 90% injector duty cycle by ~6700rpm. That's a clue.
After the new fuel pump is installed, spend some time working on your VE table. Those fuelling numbers should be flattening off around 6000rpm with a square top and VVT head. I'll upload my VE table later for reference.
Btw, your 'VD1 rich' log AFR's are getting down into the 10s at 170-180kpa.
05-26-2021, 05:48 PM
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