[kismetcapitan]

so in went my Sard 700cc injectors this morning, replacing the stock 444cc units. I got them from Nengun, so I'm sure they sent me the correct items. They popped in no hassle (even getting them into the fuel rail wasn't as bad as its made out to be), I reset my PFC injector settings to 63%, +0.18ms lag, and now the damned thing won't idle. It starts, idles fine, but once you drive a bit and then come to a stop, or even just rev the engine a touch in place, it loses its precarious balance and starts trying to die, surging back to 900rpm once a second, until it either finally conks out or some very delicate throttle work gets it back into balance. Turning off O2 feedback keeps the engine alive, but the seesaw action is still there, just not fatal to the idle.

The car was in basically perfect tune before the injector swap - I had the ignition tables mapped for snappy response and knock under 30 under full 1 bar boost to 8K rpm. Now the car bogs under throttle and I think it's running rich (I can hear lots of quiet pops and burbles from the tailpipe, plus it smells very petrolly, although I did toss the cat for a decat).

Although I had done a lot of tweaking to get my old map so good, I hit reset as I figure the 700cc injectors wont scale down in the same way as the 444cc and tried to get the unit to self-learn idle - the car died halfway during the second 10 minutes (with A/C on) after running rather smoothly up until then. Is there a particular procedure to get the car into self-learning idle mode? I reset the maps in the ETC menu, then set injector settings, then fired up the engine. Might I need to fire up the engine as soon as I reset, and then make my injector settings while the engine is running?

I do need to get my fuel pressure checked to insure that I'm at exactly 3bar and that my 444/700 correction is appropriate. But if my Nismo FPR is set at something a little different, then wouldn't changing the injector correction percent eventually hit the right number? I tried everything from 58% to 68% with no luck or joy. And with the 444cc units, and injector settings at 100%/0.00ms, everything was blissfully smooth.

I'll try to run the self-learning idle cycle again, global ignition and injector changes had no effect. Any other ideas? Could something have been missed in reconnecting everything? As I said, the car was running absolutely, immaculately and fastidiously perfect up to the moment we shut off the car and swapped the injectors.

The 700cc units were meant to allow me to boost higher, but my car is now a hobbling cripple. And I must do something straightaway - there is no one, no one at all in this country who can professionally tune a PFC. I mapped my original map successfully on my own, I hope I can get my car running smoothly again....

 

[kismetcapitan]

just a shot in the dark, but might anyone have A: Denso 700cc injectors in their car and B: their entire PFC map in an excel file?

 

[kismetcapitan]

well, after running the self-learning idle three times, I've now gotten my car to idle with the A/C on. Still lumpy and wants to cut out when the A/C is off, but turning on the A/C solves that. Car runs fine when moving, and after putting in my own ignition map, I got some nice pulls, 1.25bar, knock 21, inj duty 64%, rpm 8K. Felt nice

Still would like to have a stable and buttery smooth idle w/AC off like I did with the stock injectors, but I've got it halfway sorted and so I throw in the towel for the day. Any ideas? Could I be running extremely rich, thus causing lumpy idle and stalling when releasing the throttle?

 

[EvolutionVI]

You need to look after more things when changing injectors and fuelpressure,did you check the AFR?? Maybe it runs that lean or rich that is cant run at idle,and if it does,it cant be right under boost. Dont drive it when the fueling is wrong.

Check it first

 

[spottdog]

hi,

If they are denso 195500-0830 type injectors, then I think your lag is a bit short. I have searched and the best I can come up with is that they have a dead time of 0.96ms @3.05kg/cm2 and 14V. This was from an evo forum.

I too would be interested in seeing maps, I don't know why everyone is so coy about posting them as I think they would be a very useful community resource.

 

[kismetcapitan]

well, for starters, I'll post my map when done, and perhaps we could get a subforum dedicated to Skyline PFC users?

Also, is there an idle screw on the RB26?? Perhaps I'm trying to fix with software something that can be tuned in with a screwdriver...

 

[GTR RICH]

Paul's Homepage
Fuel Injector Technical Information - RC Engineering
might be helpfull

 

[reefyman]

hi ive got sard 700cc injectors in mine and when it was mapped the injectors were set to 50% with a lag of 0.38 runs lovely now
dont know if that helps
simon

 

[kismetcapitan]

hi ive got sard 700cc injectors in mine and when it was mapped the injectors were set to 50% with a lag of 0.38 runs lovely now
dont know if that helps
simon

jeebus, that did the trick! Would have never thought to input numbers so off from the calculated values, but yep it works, and my smooth buttery idle is back. Bless your heart Simon!

 

[ExScoobyT]

To echo what has been said above - what are your AFR`s? By changing the injector scaling you are directly affecting the AFR you are running with the same fuel correction numbers. Changing to 50 from 63 is leaning everything out.......

 

[kismetcapitan]

gonna get my AFRs checked tomorrow. But leaning everything out was a good thing - the map was, and I suspect still is, far too rich. 12mpg commuting in traffic, driving like a normal car, well, that's not normal gas mileage! Just guesstimating right now, I'm betting that I can further lean out the fuel map in the "puttering around" zone (RPM axis 1-6, load axis 1-10), and I may need to richen/maybe further retard a few cells as I got a single knock of 55 on a 4th gear pull (but I could actually hear the detonation, it popped from under the engine bay, rather than coming from the tailpipe where the popping sounds usually come from). I haven't been able to replicate that knock but better safe than sorry.

One odd thing though - the car likes the injector scaling at exactly 50%, no more, no less. I've had to further advance the timing correction though - it started having a surging idle at 38ms, kept doing it until it went away at 48ms. The idle stumbling came back slightly, and I reset it at 50ms and it's gone. I wonder if the Densos are really that sluggish, or if I've now advanced the fuel timing so much that I'm squirting the valve before it opens. The car runs great though at these settings (50%/+50ms). It implies that my fuel pressure is above the standard 3 bar (will have that checked too), although my 444cc JECS stockers ran just fine with the exact same setup.

As my map gets more precisely dialed in, I'm hoping to get the low rpm/low load parts as lean as possible, obviously with an eagle eye on knock and EGT (I trust my knock sensors, they go ballistic when the Bee*R is engaged - which is why the box is turned off and is now a dash ornament). Lean mixes and advanced timing should mean better fuel economy, as well as quicker response under 3500rpm - which means I can get to the high load/high rpm parts of the map faster, where I'll be liberal with the fueling (I feel the timing is more or less spot on for the 99RON I'm running)