Maxing out Flow Force 640cc Injectors, but with low power? (With logs!)
 

Hey all, I'm finally tuning my car for power and seem to be prematurely maxing my injectors. I suspect it's either a tune issue (i'm new to this), or, albeit less likely, a issue with the combination of parts.

Note:

1. My MAP SENSOR is reading very high compared to my in-car boost gauge. You'll see 19+ "Boost psi" below, while my gauge never surpasses 15.
2. I'm trying to dial the car in on the street as best as possible before heading over to a dyno sometime in the near future.
3. Feel free to provide any additional thoughts outside of the primary injector question.

Setup:

1. 99 Miata Newly built 1.8 with low comp (8.5:1) pistons and Manley Rods
2. DIYPNP running speed density
3. GT2871R (essentially a China charger)
4. Flow Force 640cc injectors (oem rail, pump, etc.).
5. Stock 4.3 rear with a 6 speed trans and a (temporary) 195/45/15 tire
6. Timing map is a slightly tweaked version of Braineak has used on other cars (it's my start point for now).

As you can see, according to the Virtual Dyno, the car is making well under 250hp. (Remember, low comp pistons and it's all a work in progress). I'll continue to manipulate timing and boost as I become more comfortable, but in the mean time, why am i maxing my injectors?

Attachment 182620

Attachment 182621

it calculates duty cycles based on all the injector parameters and fuel requirements you input into the tune. and the map sensor is also out of calibration. so this is most likely a tuning issue.

If the MAP sensor is correct, then you're down to 41psi of effective base rail pressure at 19psi. You could also be maxing out the stock fuel pump.

If the MAP sensor isn't correct, you should stop tuning, because everything you're doing will be down the drain when you finally fix the MAP sensor.

Incredibly quick, concise, and informative feedback! I really really appreciate it (and all your historical posts for that matter).

Tonight/tomorrow I'll thoroughly investigate my MAP sensor calibrations and fuel pump if necessary and will report back with my conclusion/results. Thanks again!

NP, your minimum vacuum is -9.4
clearly it's not calibrated right or faulty (or the engine is seriously hurt, which is not the case)

Full vacuum should be ~13-15kpa (~12.5psi).

So, I'm struggling a bit here with getting the MAP sensor to read correctly.

The log above was had its "Common MAP Sensor" set to "MPX4250" (with default values of: 0.0 Volt and 5.0 Volt at 10 and 260 respectively).

• Here're the data points I captured with this setting (PSI based on in car boost gauge):
  1. Engine off: @ 0psi : 98kpa
  2. Idle/Vacuum: @ -18psi : 35kpa (at 1,050rpm)
  3. WOT: @~14.5psi : 210kpa

• Next,I began experimenting with the MAP Sensor 0.0volt and 5.0volt values in tuner studio (creating "Custom" MAP sensor settings).
• Although I didn't make extreme changes it didn't look like adjustments to either would have got me anywhere closer to the 0 to negative kpa i should see.

Question: What other parameters can/should i be adjusting to impact how my MAP Sensor is reading reading pressure?

If your MAP sensor is a MPX4250, then the standard settings in TS are correct. If they give you the wrong values, then either your connection to the MAP sensor is questionable, or the sensor is broken. Fiddling with the settings is pointless in this case.

35kpa is reasonable for idle, but not for overrun.

where is it tapped into the source?

That port should be fine. But you really shouldn't share the line for the gauge too, at least it's not recommended.

Whelp, I'm still stumped. After giving this a lot of thought, here're the only possibilities I've come to:

1. The map sensor IS calibrated and reading correctly. This likely means:
- The Injectors actually are maxed
- The vacuum signal actually is weak on overrun
- The boost gauge is reading low

(This seems like an unlikely combo, but could something else be causing these there symptoms?).

2. The map sensor itself is faulty. (I'll order another just in case).

3. The Mega Squirt itself is faulty (Reverant built, so unlikely).

4. The voltage running to the map sensor is faulty.

Ugh.

I don't see anything in your log that would indicate any trouble with your MAP sensor. Forget PSI. How many kpa when idling? how many with the engine not running?

Both are posted above

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.

I see 35kpa for idle @ 1050rpm and 98kpa with engine off. Both seem about right. 210kpa at max boost also looks OK. The only indication that there's something off is the boost gauge reading 15psi when the MAP is at 210kpa. 15psi boost would be 203kpa. Close enough.
Just not sure where the perceived MAP issue is...
Also 250 rwhp on VD with 210kpa off a chinacharger on a poorly tuned car with uncertain VD dyno factors doesn't seem outlandish to me either.

I second the fuel pump guess.

Aha. That log shows a 109% barometric fuel correction and a baro reading of 80kpa. OP, where do you live?

New Jersey (08833)

I have FF640s as well and get a PW of 12.5ms and AFR of 12.3 at 175kpa, which is my max.
You get 13.1ms and 11.3 AFR at 175kpa. So that's pretty damn good agreement.
Now at 210kpa I would roughly expect 210/175 * 13.1 ms = 15.7ms , just extrapolating from the lower value. Add 10-20% for reduced flow caused by lower pressure differential and we'd expect 17.3ms to 18.9ms.
You're at 18.7ms and your AFR is up. Your fuel system is maxed out. Convert to return-style system and upgrade pump.

So not 6600ft of elevation, then. The MAP sensor is correct, your boost gauge is correct, but something caused the baro sensor to read a bunch of vacuum on key-on when you started the car and created that log. That explains the discrepancy between your gauge and the MAP sensor. Tunerstudio reads the barometric reading and will correct the "boost" calculation to it. It's worth keeping an eye on the baro correction when tuning, just to be sure its not causing issues like it is for you.

Your high DC% is caused by a maxed-out fuel pump. Upgrade the pump.

MSQ is set to independent sensor for baro. OP, do you have an independent baro sensor inside your case?

OP does not, since the log does not budge from 109% (onboard baro cars dance a tiny bit). OP, there's your problem.

Interestingly the baro corr is set to '0' across the board, yet we still get the 109.4%

STATUS REPORT!

Adjusting the "Barometric Correction" setting under "General Settings" from "Two Independent Sensors" to "Initial MAP Reading", has resulting in the following:

• Tunerstudio Boost PSI is much closer to my Boost gauge. It went from recording a max PSI of 19.6 psi, to 16.6 psi - Mystery 1 Solved!
• Tunerstudio Barometer went from reading 80kPa to 99.4 kPa - Mystery 2 Solved!
• Tunerstudio Fuel: Baro cor went from reading 109.4% to 100.3% - Mystery 3 Solved!

Unfortunately, injectors are still hitting 95% and the car is seemingly not reacting to adding more fuel to the map (at 5500rpm). It looks like I'm still hitting the limit of the fuel system.

Thanks again for everyone's help!! I have no idea why I changed my baro correction in the first place, but problem solved. I appreciate it! :)

Screen capture below and updated log attached.

Attachment 182526

Apologies for thread stealing. I'm having issues with my low boost Rotrex setup, and I've been reading through any troubleshooting thread I can find.

My Barometric Correction is set to "None". Should I change it? If I change it to Initial MAP reading, do I need to change any other values.

Thanks,

If you live at sea level, you should be able to turn it on and not change anything. If you live at altitude (say above ~1000ft) you may need to adjust your VE table by a few percent.

Won't that depend upon what correction curve you have dialed in?

One final yes/no question :)

My plan is to install a 190LPH-HP Walbro. Since I'm running a MegaSquirt (DIYPNP), I would NOT need to convert to a return-style style system and would NOT need to add an AFPR, correct?

Assuming there's no barometric correction, the correction should be 100.0%, or sea-level. For example, OP's logs showed a 9% fuel add at 80kpa of correction, which is like 6600ft of altitude. Small altitude changes, say anything under 1000ft, would result in a pretty small global change, enough that the fueling would probably still be within the error of MAT corrections. Thus, "should need no changes".

OK, I see that in his log now. In the MSQ, under BASIC / GENERAL, it is set for Old Method OFF, but the MAP/BARO and the table are set up for the old method (which I totally do not understand). So, it seems that the old method is being used, regardless of the ON/OFF switch setting.

So, while I don't fully understand the settings, your advice seems straightforward, and OP can easily determine if the correction goes to 100% after he turns off the correction.

My advice was for poormx, who said he has no baro correction right now. If you tune at sea level with no correction and then add correction, there should be no change.

Carloverx tuned at sea level with a 109% correction and needs to completely retune his car.

Yes, you are correct.

You may need to retune areas of the map. And definitely up top.

I tuned a few NB with flow force 640cc, 2005 sport NB, turbo with MS.

When running 15psi the injectors are at 70%~

This is just some reference input for you, about the different MAP reading, well, when all is right they read the same...

My NA turbo 460cc running 90%+ @ 15psi.

Boost pressure != Fuel usage or power. What turbo? 15 psi on a GT42 is like 600+HP.

Dynapack says 260hp

T25 turbo on the 640cc

I run a small td04h-13c dynapck says 250hp

260whp at 70%DC is right where a 640cc injector should be.

While I have more work to do, and I will possibly end up making a new thread, I feel like asking this here isn't too far off base:

Any guesses why a SEEMINGLY well running, newly built NB, running 65% DC (on FF 650cc's) at 15PSI, 93 oct, with a off brand 2871R would "only" be making ~200whp on a Virtual Dyno?
I know there could be a million reasons, but I SUSPECT my timing/boost is too mild 8.5:1 comp pistons. And while I do plan to continue to work on both (with the help of my det cans/ det muffs), it's obviously not something I want to be guessing at.

Note, my combo DOES have some very low end parts:

• head is stock,
• off brand log manifold and turbo elbow,
• off brand intercooler (full 2.5inch piping)
• exhaust has a cat (albeit from flyin miata through a 2.5inch exhaust)
• off brand muffler

That's still very lower power for that boost number. :(

Log attached in case anyone's interested in some go ol' internet diagnostics/speculation before i start messing with timing and boost again this weekend haha.

p.s. boost leak tests up to the throttle body hold boost rock solid.

(Edited post for injector size from 640 to 650)

If you asked that question without putting a new fuel pump in your car, I'm going to reach through the Internet and choke you out.

lol oh dis gun be guud

Luckily for me, I purchased and installed a "190LHP-HP" right after our initial discussion on maxing out the 650's! :)

The log says 17.0-17.6 volts for battery voltage. Did you build the regulator circuit right?

Also, do you have an IAT sensor?

1. I did not build the regulator circuit. I purchased the DIYPNP second hand; the seller claimed it came from this group buy: 99-00, 01-05 and MSM Megasquirt MS2 DIYPNP "Enhanced" group buy I have no reason to believe otherwise and if true, makes any build errors very unlikely.

2. I purchased and installed DIYAUTOTUNE's DIYPNP IAT Sensor Kit (GM sensor)

stock fuel pump

Then it's likely a combination of things. Unknown China turbo may not be doing what it's supposed to. Unknown log manifold isn't helping you, nor is the unknown intercooler (high pressure drop?), nor is the 2.5" exhaust, nor is the off-brand muffler. You are expecting optimized-setup numbers from a setup that is far from optimized.

Thanks for the info!
I'm actually 100% ok with the combination not yielding "optimized-setup numbers." I'm not ok with it not yielding "numbers optimized for this setup." As long as there isn't something actually malfunctioning or way off, I'm happy. (on a side note, the car actually feels surprisingly fast for 200whp).
My goal for the car was 270whp, and I'll likely snag a Enthuza 2.5" muffler next. and start keeping an eye out for a name brand exhaust manifold.

The car also really needs is some dyno time in the hands of competent MS/Miata tuner.

Certainly it's true that cheap, poorly flowing parts will impact the power that a turbo engine makes, but note that they do so by hurting air flow. This lowers VE, and with a properly-tuned wideband & fuel map, this means you're also burning less fuel. So that doesn't explain why you're using 260 rwhp worth of fuel to generate 200 rwhp unless the car is running pig rich.

Two thoughts from there:

1) Virtual Dyno is a good idea in theory, but it is very sensitive to numbers that you can't easily measure to a good level of accuracy, things like actual car weight, rolling friction, air drag, slope of road, etc. If you're extremely careful to control these then you can maybe use it to compare two setups, but I really don't trust it to generate numbers that can be compared to a DynoJet.

2) If your timing map is off, then that *will* substantially hurt power without burning less fuel.

IMHO, the only way to tune the timing is on a real dyno. So... take it to a real dyno and see what it says.

--Ian

My Chinese 2870 I used to have did 200whp on a real dyno at 9-10psi. That was with the FM log manifold, 3in downpipe, 3in exhaust, no cat, golf ball approved muffler, 8.4 pistons. Since manifold pressure is a measurement of restriction of flow in the system I'd say your measurement is somewhat close to what I'd expect with exhaust restrictions and timing not optimized (not that mine was optimal). It's close enough to be believed.

Just adding to what is an already good thread.
DW200 fuel pump installed in a friend's car. It replaced the stock nb2 fuel pump.
Previously the duty cycle maxed out at 6000 rpm. Now 72-74% at redline and 16 psi, 98 ron fuel.
Rods only build with a Volvo 15G (Thing is a street beast).
Not dyno'ed yet with the new engine but we think 280-290 whp.

That turbo, iirc, tops out at 240-250 at full tilt. Doubt you're touching 300, but I'm sure it's fun either way.