Fuel Problem

[adv4nced53]

Related Mods:

Air:
o Evo3 16G Turbo

Fuel:
o 1G Fuel Rail
o AMS 680cc Injectors
o Walbro 255 High-Flow Fuel Pump
o Aeromotive AFPR w/ 6AN fittings

Other:
o HKS 272 Intake/Exhaust

Tuning:
o DSMLink
o Innovate LC-1 Wideband

Problem:
Running 18psi and I have to max out the injectors to not run lean. I've had this problem since I got the cams. At 95% duty I am making 11:1 - 12:1 range but that shouldn't happen until 25+ psi. I thought I was overflowing the FPR so I installed the Aeromotive AFPR. Set it to 43psi with unplugged vacuum. With vacuum it runs about 40psi and at boost I've seen it around 45psi (antilag). I do have a bit of a boost leak but still...these injectors are maxing out wayyy too easily. Voltage is fine. Any suggestions?

PS: Will fix the boost leak ASAP.

 

[2point3Tsi]

So at 20 psi boost you see base + 20 psi and under 20 in hg vacuum you see base + -10 psi (20 in hg = -10 psi).

whoa, I thought FPR's did nothing under vacuum and 1:1 under boost. I have an aeromotive FPR and I plugged the vacuum line, set my base to 45psi, have 20-21inhg@idle and fuel pressure stays rock solid.

 

[steve]

whoa, I thought FPR's did nothing under vacuum and 1:1 under boost.

Then you thought very wrong. Ours are designed to maintain 1:1 all the time.

 

[adv4nced53]

Hg is different from psi though so shouldn't the fuel pressure drop differently from 1:1..as in:

Neutral - 43psi
5psi - 48psi
15inhg - ???

 

[steve]

Hg is different from psi though so shouldn't the fuel pressure drop differently from 1:1..as in:

Neutral - 43psi
5psi - 48psi
15inhg - ???

From the regulator perspective it must maintain a 1:1 ratio across the entire range of manifold pressures. The ECU expects that the FPR will maintain the pressure as FP = base FP + manifold Pressure. So at 20 psi boost you see base + 20 psi and under 20 in hg vacuum you see base + -10 psi (20 in hg = -10 psi)

In neutral you should be seeing at least 15 in hg vacuum. Base fuel pressure is with the hose off and plugged, the same as at 0 psi boost (or 0 in hg like WOT on a NA).

So lets assume that what you really were trying to say was:

base = 43 psi
5psi boost = 48psi (43 psi + 5 psi)

Then

15 in hg vacuum = 35.5 psi (43 psi + -7.5 psi)

 

[2gGSX]

Multiply in. Hg by 0.4912 to get psi--15 in. Hg is equal to 7.368 psi.

 

[steve]

, dividing by two is a close enough conversion from in hg to psi for what we are doing here.

 

[2gGSX]

Blasphemy! If people get awards for calculating pi to 1,241,100,000,000 digits (December 2002 by Yasumasa Kanada of Tokyo University) the least we can do is use the extra 3 sig figs!

On a serious more note, just divide by two.

 

[adv4nced53]

Ok so my idle would make sense then. Since the cams I've been getting around 12-15inHg, which would be -6 or -7%. I need to hop on a dyno to make sure it does well under boost.

 

[2gGSX]

STFT should eventually level itself off to hover around 0, otherwise you've got some extraneous problem that the ECU can't correct, such as having injectors bigger than you're compensating for or base fuel pressure being very very off.



Looking at the idle log...
1. You need to go to ECU-->Misc-->turn on Invert CAS
2. Verify that you have the plug wires switched correctly
3. Log ThrotPos and make sure everything is set correctly (RawThrotPos=32 without touching the pedal, 255 at WOT). The procedure on how to do this is in the user's manual.
4. Adjusting your BISS and pay attention to ISCPosition and get it close to 30 at idle, and LrndIdleAdj close to 140. It looks like you have to back out the BISS, which will cause the ECU to close the ISC and thus give you lower numbers.
5. Zero out your fuel sliders, that is not normal and your global fuel modification is obviously off. Also, those are your WOT tables and thus do nothing in closed loop operation. Due to the fact that your LTFT Lo and LTFT Mid are both very positive, your global fuel setting is too low. After you zero the sliders out, set your global fuel to -21% and start driving around until you get stable LTFT readings and then post another log. If your LTFTs are both closer to 0, then you're wrong about your injectors being 650's.
6. Zero out your airflow sliders.

I would post these logs up on the DSMLink forums as well since I may have missed something.

Have you considered this at all?

I'm not sure how else to explain it--the fact that you're adding fuel on your WOT map in order to even get to 11.0-12.0 AFR's should be a sign that your global is pulling MORE fuel than you're supposed to. The LTFT data only gives more credit to this theory.

 

[adv4nced53]

But doesnt positive LTFT mean the car is running lean and thus adding more fuel? I'll try the CAS and check the wires but I doubt it's any of those.

I didn't know that the tables or only WOT, so it makes sense to lower that so I can correct the trim. Will try and I'll let you guys know how it turned out.

Thanks for the help