EFIDynoTuning Forum

canuck1

Obviously my goal is to use the lowest ms value I can to work at warmer temps, but I’m trying to calculate the upper limit.

I was running the same injectors at 55psi in my first tune (using different data). The new data works vastly better in every respect, but I didn’t want to alter any of the manufacturer’s values to start, so I reduced pressure to 43.5 psi to match what was provided.

Since pressure impacts injector flow, if I had a working FN348 (.42) ms value at 55psi, doesn’t it mathematically calculate that at 43.5psi that same volume of fuel would require something approaching .47ms?

Am I on the right track?

Sean

canuck1

FYI, I've been using the Continental data for my Siemens-Deka V (shorty) injectors since the earlier this year. I have to tell you it's a night and day improvement over the earlier model (Deka IV) data I had tried using before. It's nice to be able to input changes and have the expected result come back to you in a log. It helped me figure out very quickly that my MAF transfer function was accurate and the car is running best ever! I'm super happy you pointed me towards this info. Hope it works out as well for you when you get around to working on the truck again.

Sean

canuck1

Nope, no luck. Increased pump prime time (from 3 seconds) to 6 seconds after lowering higher temp cranking pw from .49 back down to .42 ms.

Parked warm car, left it for 10 min to let it heat soak sitting in my garage, would not fire. 2nd attempt it sputtered once during cranking, but no start. Pushed the pedal to the floor for third attempt to make sure I didn't flood it, no difference.
Anyone else dealt with this???

In my case, .42ms of pw amounts to 25% more than calculated requirement.

Sean

canuck1

Thanks. It was at .42ms for 200+ ECT but when I switched the injector data to the stuff Chris at PAS pointed to, it was only provided for 43.5 psi (dropped from the 55 I was running).
I think you’re pointing to the key element. Main issue is restarting after getting fuel (embarrassing when it doesn’t go vroom!). I’ll report back after increasing pump prime time & dropping PW.
Sean

canuck1

My injector size and engine displacement are accounted for, but I had to keep bumping up the higher temp values (above 160) to where its beginning to make me nervous:
-65536 5.70
-40 5.70
0 5.22
40 2.50
80 1.21
120 0.82
160 0.49
200 0.49
65534 .0.49

canuck1

OK, thanks once again. It must be near the minimum at 800, since it won't stabilize at a lower rpm. I'd be OK at 800 if it wasn't over/under shooting that value. I have a good idle air log now, looks very close to right. Is there something I can do to keep idle rpm closer to the actual nubase setting? Maybe raise it further or perhaps alter my spark advance??

Sean

canuck1

A9L2 uses a stoich AFR setting of 14.079:1. Where I fill up, the premium fuel is labelled "NO ethanol". Do you think that's a valid enough reason for me to change my stoich AFR to 14.64:1? Any precautions I should be aware of?

Sean

canuck1

OK, so I drew up tables in Excel of my ATMR/temp isdc values and it looks like they correspond very closely to whats in the FN1862 ISC multipler base target table. I gues thats why Desmaf is 0, is that correct?

I still would like to lower and stabilize my idle rpm. DSDRPM is 800, but its typically +/- 70 rpm. I'd like to see if I can set it at 750 and maintain within +/- 25 rpm. Will I end up chasing my tail for little gain if I mess with it now? Where should I start if I decide to try?

Sean

canuck1

I've not been keeping up to date and have only just learned about new method for dialing in idle air in A9L2:

The new file has dashpot and the isc multiplier simplified even further to make dialing in the idle air iscdc extremely simple. How simple? Stupid simple!!!

iscdc = isc multiplier table value

dashpot = +iscdc adder
ipsibr (desmaf_pid_n) = +iscdc adder

The logged dashpot value will be the iscdc added to the base iscdc (the base iscdc is the value in the isc multplier table).
The logged ipsibr correction is the ISCDC correction for adjusting the isc multiplier table. I.E. (ISCDC = ISC Multiplier table + ipsisbr)
An ipsibr value of 0.10 means its adding .10 to the iscdc.

DASHPOT gain value of 0.001 comes out to (TPREL * 0.001) so tprel is the iscdc adder for dashpot.
EX: 750 tprel (wot) * 0.001 == 0.75
at wot, the dashpot value will be 0.75 therefore dashpot is adding 0.75 duty cycle to the isc.

E"XTREMELY SIMPLE. This will make dialing in the base iscdc in the isc multiplier table about as easy as possible. You simply look at the iscdc at a given cell and plug that value in and done.

I have a new dashboard item (DESMAF_PID_N) but there are zeros showing there.

What isc multiplier table do I need to enter values into? Is it FN1861 ISDC Base Targe Neutral/Park (ISC Multiplier) or one of the other variations that are listed?

Any other more explicit tips about how I enter the isdc value at (given run time/temp)?

What role does Desmaf play?

Sean

canuck1

Just to follow up. I’m not sure whether the difference was installing the latest version of A9L2 and overwriting an error in my earlier bin or maybe using an older (modified) ADX but all seems normal now.

Sean

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