Maxing out Flow Force 640cc Injectors, but with low power? (With logs!)
#1
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:
Note:
- 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.
- 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.
- Feel free to provide any additional thoughts outside of the primary injector question.
- 99 Miata Newly built 1.8 with low comp (8.5:1) pistons and Manley Rods
- DIYPNP running speed density
- GT2871R (essentially a China charger)
- Flow Force 640cc injectors (oem rail, pump, etc.).
- Stock 4.3 rear with a 6 speed trans and a (temporary) 195/45/15 tire
- Timing map is a slightly tweaked version of Braineak has used on other cars (it's my start point for now).
#3
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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.
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.
#4
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.
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!
#7
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).
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):
- Engine off: @ 0psi : 98kpa
- Idle/Vacuum: @ -18psi : 35kpa (at 1,050rpm)
- 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.
#8
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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.
#11
- It's tapped at the upper/back vacuum source on the intake manifold (borrowed image below)
- It runs across the firewall and enters the cabin in the factory hole in the firewall a few inches from the brake booster.
- Once in the cabin, I'm using a tee to also feed my boost gauge from the same incoming line.
#13
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.
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.
#16
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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.
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.
#17
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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.
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.
#20
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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.
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.