Battery voltage Latency for Precision 1200cc ???
Anyone who wish to help?

 

bump for any any help on denso 720's for an 03 evo

 

check the last 2 pages dude come on now

 

Ok, this is probably a basic part of this concept... but I'm trying to get it now that I dropped in some RC 1200's this weekend.

When you increase the injector latency the result will be more negative fuel trims (more fuel and negative AFR change), because the ECU assumes it takes longer to open the injector and thereby sends the fuel pulse longer.

Is the above statement correct?

If so, I think the method of adjusting latencies for getting the Mid/Low long term trims closer to eachother (mentioned here and here) does not work in practice beyond DSMLink. In trying to get my values closer I've mostly just made my fuel trims drop, and the STFT that used to by a nice straight up and down slope has turned very jagged and sawtoothed, as well as the car *seems* to run worse.

I get the % change at different pulse widths explanation that means that should provide more of a change at idle than cruise by adjusting that latency, but it doesn't seem to work well in practice by my experience. Can anyone else comment?

EDIT: Sorry, I meant to mention I think MAF scaling/tuning should probably replace step 5 & 6 for getting the trims close to the same.

 

you mean 20 pages ago

I did this over a year ago

Scaling = 622

4.7V = 3.864
7.0V = 3.456
9.4V = 2.856
11.7V = 1.320
14.0V = 0.888
16.4V = 0.672
18.6V = 0.408

 

I am about to install some FIC1000's and would like a good starting point if someone has one. I will be doing a tune for pump and a tune for E85.


Thanks in advance

 

I have looked through the pages and have not been very successful in finding what i am looking for. Noone has a good starting point for these?

 

I would use the same latencies for the rc 1200's as the rc 1000's to start. Reason being is that rc rates the 1200's at 1200cc's at 55psi and at the standard 43.5 psi they flow like 1050's so I would think there would be a negligable difference between these and the 1000cc injectors.

I think yes. This is also the way I've come to understand it.



I have no idea about the rest and the MAF scaling...I'm still learning too.

 

Fost,

The stuff mentioned in the early posts is correct. It took me a week to keep it straight in my head but it does infact do as claimed.

1. the 14V latency value is really the only one that counts, the rest are for extremes in battery voltage which you rarely see. So the 14 V value is the critical one. I figured out the slope of the latency line from the spec sheet and then offset the rest of the values after figuring out the 14V one.

2. Changes in latency do effect idle more than cruise, so if your trims are unbalanced adjust latency. If idle trim is higher more latency. If cruise trim is higher less latency. You should be able to make adjustments and see when the trims converge and then diverge.

3. I noticed that you really need to go the whole 16 mins and maybe more to get the trims to settle. Don't cheat at 15 mins and stop, you'll miss that 4th cycle which can really change things.

 

jid2,

The 11V is important too.

Both the 14v and 11v are the critical values. But 14v is the more critical because the car runs closest to the 14v most of the time.

 

Here are the scaling and latency for FIC 750 injectors

Scaling 650

Latency
3.312
2.04
1.296
0.792
0.72
0.504
0.336

These worked fine and got the trims to +3 on the LTFT_low and LTFT_mid.

 

I logged voltage for a few days and never saw anything but 14V 99.99% of the time. At Idle there is a voltage dip (10V) about every 4 mins, but it is literally a blip of .25s. I think you are good to use the same slope as what the stated latency should be offset for your 14V findings.

 

Mine doesn't idle at 14v, it idles at like 12.5-13, and drives at 14-14.5

..... but I'm not an EVO either

 

Every single Evo that has been through the shop that has been healthy has idled and cruised at 14v.

The ones that haven't either had battery or alternator problems.

 

no help on the fic 1000