Badog

I am thinking about using PFC settings 64.5 and 0.04 for the 850cc primaries. I tried 100/-0.04 but idled like caca.

Suggestions? Experience? TIA!

TYSON

You have to use the 64.5, becuase the original injectors are 64.5% of the size of your 850's. You were dumping in a ton of fuel with 100. It will still probably lope a little at idle, mine did. I got my 850's from RP, but when I called Rocky he didn't know if the spec were the same as the originals. (0.04) Moving it up and down did change the idle quality, but I left it at 0.04. I haven't done a complete tuning with mine yet, so it is very rich down low.

silikenrf

I found 850cc primaries to work great once you have leaned out the idle circuit (tuned the vacuum cells). The oil gets saturated with gas pretty easy when your tuning.

RX794

You can use injectors as big as 1000cc in the primary position with no problems, I am personally using 950cc's with no issues whatsoever.

TailHappy

I personally don't see how you guys are succeeding with the big primaries. I'm ready to rip them out and go back with 550's. As I lean out the main percentage, anything below about 68% starts causing MAJOR tip in problems, and it seems like the more I try to adjust the individual cells, the more problems I make.... Seems to make more sense to me to just put the 550's in the primary position since that's all that's ever needed for cruising, and then put big 1600's in the secondaries. Sure is a lot easier to tune for WOT than it is for cruise...or at least that's been MY experience.

And to add...I can't seem to do ANYTHING to get the idle leaned out above 11:1. It's either 11:1 or stalling. I don't like the idea of trying to use lag to trick it into running leaner...

RX794

Are you using a datalogit?

TailHappy

Yep. As I reduce the 1-5 P and N cell block, it has no effect, until I reach a certain point, and then car stalls.

Though I WAS wondering... I have my idle set at 1100. I remember a datalogit thread a while back where people were trying to set their timing at idle, and it wouldn't work until they set their idle to 0rpm, set the ignition, and then set the idle back up to their preferred RPM. I have yet to try that with the fuel maps...

Anyway, I don't understand why I have such trouble, and others have no problem at all with the 850s. Maybe I have some kind of non-standard streetport...

ZoomZoom

iTrader: (2)

"carlisi"runs 850 low IMP Pri 1600 cc low IMP Secwith his PFC. From what he has mentioned it was not as easy as plug and play. He might be able to elaborate further if you PM him.

TailHappy

Thanks, I PM'ed him with this thread address to see if he could give us any additional input.

On a side note, do any of you guys know if I can just plop my 550's back in, or did the grinding process to get the 850s in ruin the rail? I had my mechanic install the 850's when he was putting in the new motor, so I didn't see the process first-hand.

R2Germany

You have to lower the minimum possible amount of injected gas working with a stable idle. Go to Settings 5 and try the following values for
INJ Sc Lag (uS) vs BatV
0,568
0,768
1,048
1,408
2,008
2,840

Be cautious, the overall map will be quite mixed up and might be to lean on your
personal car. You have to retune the whole map. A wideband O2 sensor is inevitable.
Start tuning the whole vacuum to 14,7 in P1 to P10-12 and then lower the AFRs from
P10-12 to Pxx according to your desired levels.
MY idle AFRs are bouncing a bit beween 12.0 and 13.4 and idle inj duty is 2.7/2.8%
I was never able to lower the idle inj value below 2.7/2.8%.
If you experience similiar IDLE AFR values I might mail my current map.

silikenrf

That might be the difference some successful 850cc primary users just got them cleaned and spec'd at Marrent and put an extra O-ring in. Worked like a charm. This was an arduous decision, but after tuning (datalogit with O2 and EGT feedback) and many posts with Max and Chuck Westbrook etc. I am glad I did it.

TailHappy

Well I finally got some good advice and now I'm much happier with my 850's. Had a forum member suggest using 80% and -0.4 lag, and sure enough, it has made my maps a lot closer to where they should be. I pulled about 10% out of the idle cells and now I'm idling at 14:1. Added about 10% to the low RPM high load section, adn bumped up the cold water enrichenment, and now things are looking great. Just a little bit of hesitation in some areas to take care of, but that shouldn't be a big deal. I'm a happy camper again.

AlienHack

RAISE FROM THE DEAD!!! lol
sorry for ressurecting but its time for me to do this mod. actually 12 hours ago i did the primary rail mod and installed the secondaries... so i have 4x850cc . i did all the recomended setings in the datalogit/fcedit but.... i came to the exact position tail happy was

As I lean out the main percentage, anything below about 68% starts causing MAJOR tip in problems
And to add...I can't seem to do ANYTHING to get the idle leaned out above 11:1. It's either 11:1 or stalling.

as far as i understand i have leaned the inj map (and the base map) to their minimum but the idle AR is stuck at 10.8 . the only way to lower this is by adding lag but this makes the whole map a mess.... so i have to either choose a 10.8 idle and perfect map or a 13 idle and a mess map that i have to make over again.... :-( maybe the 850 primaries were not such a good idea after all... :-(

Slides

The dead time values you are using are obviously too large so that the minimum open time overfuels or it cuts out if you try to go leaner. Reduce the dead time numbers and try again.