NefMoto

Hello,

I have a ME7.5 project with 1000cc injectors.  The TVUB, and KRKTE calculated appropriately.  Idle raised a little to ease the pain, but still having fueling trouble at idle.

At idle it runs rich constantly, .85-.90, the ECU shows O2 correction bouncing around -10-20% yet the injector on time is constant and appears to be on some kind of limit?

Tried lowering TEMIN, it is .6 stock in the file, I've cut it in half with no change in idle.  Read the entire section on injector on time calculation and haven't seen any other values that might be interfering.

Any ideas????

If you're getting corrections that large (and have lowered TEMIN), then KRKTE and TVUB aren't setup properly.

post your injector brand and spec sheet and your current values lets see whats wrong

The issue though is that at low load/idle the injector on time stays dead constant and it seems like something else is preventing it from going lower. 

At low load I can literally see in the logs the same injector on time being used for 3.5g/s MAF and 4.5 g/s MAF (just giving it a touch of throttle above idle)

Bring up the load a little and very little correction, full throttle and very little correction so KRKTE looks good.

Taking you at your word that TVUB is correct requires me to believe you understand what you're doing. Please post the values you're using, along with the fuel pressure you're running.

I'm guessing when you said you read the entire section on injector on time calculation, you meant the S4wiki.
If you look around on this forum there is a thread or 2 where somebody has already dialed in some 1000cc injectors, EV14 I think. Maybe they had the same problem and solved it. use TVUB, KRKTE, FKKVS, and TEMIN as search words in the search box of the main forum page or use Google and put in the search:   site:nefariousmotorsports.com <----then after here, put in whatever search words or phrases.

You are probably wasting your time with TEMIN though. Unless the engine requires for injector on time less than TEMIN, lowering the value of TEMIN will do nothing. Stock TEMIN for my HSbox is .7493 --->IF<--- I defined it properly in the definition file. I have never seen injector on time that low ever on my 1.8t. I'm running 550cc injectors though but I don't think you need to mess with TEMIN unless you are going 2000cc+.
Which 7.5box are you working with? What is the address for TEMIN in your definition file? I would like to confirm the address in mine if possible.

the fuel system for ME7.5(mine anyway AWP motor) is sequential, so fuel pressure is referenced by boost! The ECU sends PWM signals to the fuel pump to raise the fuel pressure at a ratio of roughly 1 to 1 in psi. Before this happens the fuel reg references vacuum. So this may explain why you don't see changes in the injector on time like you explained and are expecting.

You have to adjust TEMIN/VA with 1000's and idle is not the lowest load point.

1000cc@4bar runs around .55ms effective ontime just on idle.

He's set TEMIN to .3ms, I'd think that would be sufficiently low (for idle at the very least).

I think he's using wacky TVUB values or hasn't adjusted for a change in fuel pressure.

Yeah .30ms is sufficient, but as if you say TVUB is super high he will hit that TEMIN anyway and O2 correction shuts off.

TVUB must be over like 1.4-1.5ms@14v to hit a TEMIN of .30ms at idle :)

It is 4bar (58psi) returnless on an Audi.  I have read 11.40 Calculation of injection time.

I've run several different sizes of injectors and never had issues adjusting TVUB/KRKTE before.

I've tried everything from stock TVUB (very low) to the dead times from the data sheet (quite large) @12v for example that is from .611 to well over 1.0  It idles the same... always 1.8x ms.

According to the documentation, I think in theory you're just supposed to use the dead times from the data sheet at the correct pressure and then FRLFSDP is supposed to take care of the rest in terms of the ambient reference pressure.  In these files though it does seem that using the measured dead times would give way too high an injection time and when stock values are compared to stock manifold referenced TVUB values in other files they seem generally lower.

It does seem that it is not actually in closed loop, it just mindlessly runs rich etc and the additive trim does not move off of zero.  I'm pretty confident that something is being calculated that is below a threshold and then wham toss it out and plug in a default value.  How else do you get the exact same injector on time for anything between 3.5-4.5g/s?

As far as finding TEMIN/VA in all the files I've seen they are just before the TVUB axis values, one or two 16bit values just before 05 71 8E AA C7 E3



 

Is rk_w the same at 3.5 g/s and 4.5 g/s?

TEMIN should be set to the "knee" at the bottom of the low slope. The smallest change at this pulsewidth with cause the engine to stall. This should be calculated and not just arbitrarily set out of the way.

1.8ms may be in the low slope and require linearization.

Yes I believe rk_w is the same, same day, same ambient temp, idle to full temp, just a higher idle set point.

Once you go high enough with the pedal to generate a pulsewidth at or above 2ms happiness.

So you're saying that TEMIN should be set so that in conjunction with TVUB the smallest pulse width that could be generated is above the low slope "knee" in the linear deviation correct?

For example in the 6th plot down or so, "Linearity Deviation @ 4 Bar" -the minimum should never be below 1.5ms or so and anywhere between there and 2ms should expect hefty adjustments with FKKVS?

http://www.injectordynamics.com/ID1000.html#Dynamic Flow Characteristics - 4 Bar (58.0 psi)

Thanks for the tip!

If rk_w is the same, then most likely ti will be the same.


Yes, TEMIN is the minimum final pulsewidth.


Yup.

Do they provide any hard data (not just graphs) other than static flow and battery compensation?

Yup I'm stumped then two latest attempts:
TVUB: .88 @ 14V (ECU reports 13.5v at idle).  TEMIN at .30 => idles .85-.90 at 900rpm 1.8x (ms) TI

TVUB: .58 @ 14V (ECU reports 13.5v at idle).  TEMIN at .25 => idles .85-.90 at 900rpm 1.8x (ms) TI

Target 1.0, O2 correction 1.0, ECU knows its rich but wont lower the injection time... then get up over 2ms and its < +/-4% correction.

Added a 10% linearity correction between 1.5-2.0ms and its still crap, no change... >:(

Added?

What changes to FKKVS did you make?

If the original value was 1, you should have changed it to 0.9.

Posting a log might be a good idea too.

Why would you bump a 11 year old thread, just make a new one with proper info.