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Running out of fuel pump?

narancs

narancs

Member
Joined
May 21, 2007
Location
Hungary
Hi,

2.3 T5, stock 315cc injectors, 18t and stock 960 (whiteblock NA) fuel pump.
The map is tuned for 1.5bar but I'm not letting it boost more than 0.5bar. The reason is the injectors are over 110% duty cycle :wtf::wtf::wtf:
wtf_zps8c547ac5.jpg


I don't think I've run out of injectors, all I can think of is the pump can't keep up.

Thoughts please?
 
Start by upgrading your fuel pump's wiring, if the pump is known good of course! Or install a Bosch 044 and be done with it!
 
Ok, what I wanted to ask is, is it possible that the injectors are over 110% DC because the pumps is a POS? So the injectors (VEMS) have to corrigate the loss of flow by staying open longer? Or, should I be looking somewhere else?
 
I didn't think VEMS monitored fuel pressure, unless its' adding pulsewidth to the injectors due to a lean WB02 reading.

Regardless, you're out of injector. The sweet spot should be no more than 80% if I recall correctly.
 
if the calc is the same as the one for MS, I'm not really sure it's very accurate. you're out of pump if you can watch the fuel pressure drop in boost, instead of go up slightly. I'd be surprised if you were out of fuel pum at 7psi, and surprised if you were out of fuel injector. What are your idle pulsewidths?
 
and if 110% wierds you out, I should post one of my datalogs from the 940, it's hit 170% ;)
 
What are your AFRs? If you're out of pump volume, the AFR should be climbing beyond what you can tune for with those injectors. I'd start with larger injectors, since you already know stocks aren't appropriate for higher output.

170%? Now that's a serious lack of attention to tuning and appropriate components. How you come have even got close to 100% without being aware the setup was f'ked?
 
Daviticus said:
I didn't think VEMS monitored fuel pressure, unless its' adding pulsewidth to the injectors due to a lean WB02 reading.

Regardless, you're out of injector. The sweet spot should be no more than 80% if I recall correctly.
Click to expand...

that is what I was thinking.. although the AFRs close to my target AFR

linuxman51 said:
if the calc is the same as the one for MS, I'm not really sure it's very accurate. you're out of pump if you can watch the fuel pressure drop in boost, instead of go up slightly. I'd be surprised if you were out of fuel pum at 7psi, and surprised if you were out of fuel injector. What are your idle pulsewidths?
Click to expand...

well... it is an old pump, and slightly noisy... sooooo
I def. not out of injector at this power level..
and I don't have a fuel pressure gauge either :(

hot idle PW is 2.5ms


lookforjoe said:
What are your AFRs? If you're out of pump volume, the AFR should be climbing beyond what you can tune for with those injectors. I'd start with larger injectors, since you already know stocks aren't appropriate for higher output.

170%? Now that's a serious lack of attention to tuning and appropriate components. How you come have even got close to 100% without being aware the setup was f'ked?
Click to expand...

Afr is 12-12.6. 12.5 is the target.
Haven't tried add more fuel to this area, but it seems it can keep this level easily.
 
If AFR's are stable and not climbing into lean range, I don't see where there is an issue, with volume. If your logging is accurate, those injectors are away saturated. You want injectors that are below 85% in your target boost/power range.
 
narancs said:
I'm running ~8psi of boost on a td04-18t..
Click to expand...

Unless your logging is way off, you absolutely need larger injectors. Just because you're only running 8psi is meaningless if that recorded duty cycle is accurate. So, either log duty cycle another way, or assume it is accurate and get larger injectors, and an adjustable FPR

18T should be paired with Volvo Blues or Greens, over 400cc in other words .
 
lookforjoe said:
Unless your logging is way off, you absolutely need larger injectors. Just because you're only running 8psi is meaningless if that recorded duty cycle is accurate. So, either log duty cycle another way, or assume it is accurate and get larger injectors, and an adjustable FPR

18T should be paired with Volvo Blues or Greens, over 400cc in other words .
Click to expand...

I assume that VEMS is correct about DC


Any advice how to log DC any other way?
 
narancs said:
I don't have the log with me, so I can only tell what is on the screenshot above.

21.4mS @ 6500
Click to expand...

http://www.stealth316.com/2-calc-idc.htm


You need bigger injectors. There is a calculator in there along with explanation. If I were you, and my goal is to get 20psi, I'd get at least 1000cc injectors to bring those pulse width numbers down.

At 6500 RPM, 14.6ms injector pulse is roughly 80% duty cycle. You do not want to go over 80% duty cycle, so you have to calculate what injector you need for the power goal you have in mind.
 
linuxman51 said:
and if 110% wierds you out, I should post one of my datalogs from the 940, it's hit 170% ;)
Click to expand...

Agreed. Everyone saying he's out of injector is missing the fact that high duty cycle also happens when trying to compensate for low fuel pressure.
Being its a 5 cylinder, so there's 5x315cc, no way they're done at 7psi.
 
so then my 34ms @ 6000 is way out in left field eh? :-D I don't think I'm out of pump tho, I'm pretty sure I'm out of injector. 550's + e85 + 17psi (on a 4 cylinder). heh heh heh heh.
 
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