I actually have a legit VII, imported from the UK (I think at least). It is pretty damned similar to an VIII except for the AYC and ACD.

Dan

 

Interesting.

Do the latency values in the ECU actually reflect true values or are the scaling just something somebody came up with that roughly approximates what they think the values were?

Also, isn't there more then one latency values that are always used? Base Latency along with Battery Latency?

 

I hadn't thought of that, I hope beyond hope they are legit values...

I don't know enough about injectors, but I seem to recall what you are talking about. With the information sheet given to me by Injector Dynamics, only one set of values is listed, based on different fuel pressures.

Dan

 

The latencies used in ECUFlash are derived from the ROM code and time slices used by the code. They seem to be pretty close to reality.

 

Now what does the High Trim tell me?

Dan

 

Impressive... I know the injectors are marked 1000cc under gasoline test conditions, but compare to other injectors at about 880cc (kerosene test fluid is industry standard). I'm surprised they scale out so large for you.

The difference in e85 scaling between my RC 1200cc injectors is only ~88% while figures for rated flow (using 1150 cc and 880cc) are closer to 76%.

Unfortunately my IDC is ~90% on my current injectors, so unless I bumped base fuel pressure up (which I would, it just adds another cost and complexity to the setup) I'll be a bit low on flow for my current setup.

Let me know if you want me to take this question elsewhere, but it is semi-on-topic: Does anyone know of a 50 or 55psi base fuel pressure regulator that fits our rail and flows well enough (and still fills all other requirements IE 1:1 etc)?

Mind posting a copy of it for others to use? If nothing else it will get you a double check by the gurus....

Trims are bracketed by airflow hz. low -> mid ~50hz and mid -> high 1600hz

 

Its called a hammer, vise, and 1/4 drive extension and 30 min, you could get the stock fpr to 50-55 base pressure. Yeah its not the best way......but it works

 

Travis the hammer and/or vice is a DSM trick. You don't have a DSM now do you?

 

No prob... you may notice that I did not use the exact latency numbers given out by the formula. I used it as a solid estimate and then added my own opinion before entering it into the ECU.



I figured that out for the most part. I was more interested in what changes High Trims tell me I should make if the numbers are out of wack.

Dan

 

Someone makes an adapter that allows generic fprs to hang off the fuel rail.

 

Oh, I'm all over the DSM crush-mod, I'd just prefer not to go on/off/on/off until I got it right Part of my on-the-end of the fuel rail thing was to prevent giant FPR that doesn't move with the engine syndrome (AKA my old DSM). I might wind up doing a crush mod just to see what happens there, but then I need a fuel pressure guage and a place to locate it and all of that other good stuff... and then I'm just tempted to buy a bunch more goodies .


Essentially you should never see the high trims adjust on most of the models. They are a relic. You cross out of closed loop ~100 load (depending on the car/table/RPM) which is almost always under 1600hz. It is near impossible to be under the load barrier and over the airflow barrier, especially for any significant enough amount of time to adjust the long term trims.

 

I guesstimated the latencies based on the cheat sheet that came with the injectors (since the battery values don't match). And have done some very minor adjustments to those values since. Have had the scaling from 835 to 750, currently at 790.

my town cruise is really close, the highway aspect of cruise wants to subtract more fuel. right now I think my trims run from +1 & -1 to about +8 idle and -8 cruise, depending on the drive conditions.
Since I've not heard others express the same issue concerning low speed cruise and high speed cruise I may have some more tuning to do.

used Travman's latencies and had to up the scaling to 835. strange because it was an increase in latencies from before. However I introduced a variable into the picture. Removed one of those restrictions from my exhaust. I continue to be amazed how much exhaust restrictions play in fuel maps too.

 

Use your high school math skills and build a function based off the given latency values that cross at nice whole decimal numbers. Use the function to find out where the line would cross in the ecu's hex brain. I had to add a bit of latency, which I added to the whole curve by percentage as that is how a coil works in practice. That is the second function that crosses the Y axis at a higher point.

 

After spending an hour cruising around town my Trims...

Low: -2.449
Mid: 3.042
High: No changes

These both stayed pretty stable after some time.

Good enough? Or should I make changes? Thanks.

Dan

(PS No problems with hot starts)

 

Great, now what are the latency and scaling values that you're using in ECUFlash?