Dragon

I think anouther thing that is going to affect the injector lag time is the port and port timming, the port opening sooner etc.. the -.12 setting will cause the injector to fire earlier to match the side port opening sooner etc..

So basicly the pulse width of the injector and there for the amount of fuel injected should still be the same. what they are probably trying to do is match the injector to fire in conjunction with the port opening and closing to maximize fuel intake in to the combustion chamber during each intake cycle of the rotor... Also when ever you change diffrent things on you car that affect the intake of air you are slightly changing the velocity the air moves threw the intake, this will also affect the time it takes for the fuel to travel from the injector to the port and there for the injector lag time as well... just my $.02 don't know if I'm right, but it sounds logical...

twokrx7

iTrader: (1)

Stephen,

I did not use another intake air temp sensor, just common sense. After shutting off a warmed up motor the intake air temp will climb as heat transfers from the engine. If you drive in ice cold air afterwards, the intake air temp sensor will take forever to come down. You can do a simple test and that is to put your hand on the cool IC outlet while your intake air temp sensor is reading 40+degC!

Kyle

SPOautos

Yea, I've always suspected that but was wondering if you did a test with another sensore in the IC pipes to confirm.

Thanks
STEPHEN

SPOautos

That does kinda make sense. Most of the xs maps I've seen were cars with streetported motors and they all had the -.12.

Anyone else test thier? Has anyone else had thier PFC tuned at XS without a streetport? If so look at your inj lag and see if what it is.

STEPHEN

twokrx7

iTrader: (1)

Both the ported and non-ported XS maps (datalogit reads) that I have seen use -.12 for the primaries. Here's an interesting datapoint ... one of these maps use +.16 for the enlarged 1300 cc secondaries. I emailed RC engineering and they recommend +.2 to +.3 for the enlarged secondaries. Anyone else?

Kyle

SARX7

When I ordered my 850's bored out to 1300's Wayne @ RC told me to use .1 to .2 for the lag time.

A friend of mine works at Southwest Research and they should have an exhaust gas analyser that I we can test the theory here. I'll ask and see if we can run some test with it, he's already offered to help me tune the PFC before.

Drew

cewrx7r1

iTrader: (2)

I got hold of a dual trace scope, and hope to use it this weekend to verify what and how affects the primary injector pulse. Hope I can get it stabalized with the way the idle jumps around.

Scott Olsen

If you look at the injector settings page of the PFC manual, it gives you the correct lag time settings for 4 different size injectors:

550cc: 0.73 ms, 650cc: 0.75 ms, 850cc: 0.77 ms,
950cc: 0.80 ms

Continuing the trend exhibited here, you can get a good idea of what the best value would be for larger injectors:

1200cc: 0.875 ms, 1300cc: 0.90 ms, 1600cc: 1.00 ms

So, the lag time correction values for enlarged secondaries theoretically should be ~+.10 for 1200cc, ~+.13 for 1300cc, and ~+.23 for 1600cc.

I don't see why these value should be changed from 0 for the primaries if they are stock 550's. The manual says that the lag time for the 550's should be 0.73 ms, I think we should just trust that number.

Sorry if this is just pointing out the obvious

ech

More pointing out the obvious.

If you have an XS mapped PFC, don't assume that manually loading the "Base Mod" or "Base Stock" maps via the commander will work. That could cause problems. I would think the only way to undo their work would be through them, or with a Datalogit.

cewrx7r1

iTrader: (2)

I connected the Tektronics scope to one of the primary injector leads at the ecu connector. After adjusting a few controls, I got one clear saw tooth pulse to show up.

I played around with the temporary fuel adjustment and added so much fuel the engine started to run rough. Added 60% more fuel at idle, but I did not see any change in the pulse width.

Spent about 1 hour with no results and gave up on it.
Could be that the scope I used is really not suited for low frequency DC measurements. At 850 rpm idle, that is only about 14 cycles per sec of injector pulsing.

spyfish007

Most Tektronic scopes are really good. You should be able to see changes easily. Are you sure you had it setup correctly? You should be able to see one or multiple pulses show up.

TYSON

I don't know if this thread is dead or not, but thought I would add my own observations.
I installed the 850 cc injectors that RP sells online as my primary injectors. I made the assumption that these are the same injectors used as secondaries, and adjusted my PFC according to the information given in the manual. 64.5% +0.04 lag time. The car started immediately and idled solid at around 800 RPM with the air and coolant at room temperature. After a short drive to warm up, I pulled back into the garage. Next day, started the same, so I assume no leakage of fuel into the engine. When the car is well warmed up, there is a noticeable lope in the idle, and it idles between 850 - 810 RPM. Adjusting the lag time up to +0.2 on both rotors made no difference, though adjusting down to -0.10 smoothed the idle out and reduced it down to 750 RPM.
As for the exhaust, this adjustment made an immediate difference in the stink level of the exhaust. ( Not scientific) My car has all of the emissions gear removed, except for the disabled EGR and the plugged, ( assumption), stock cats. Before, the exhaust was enough to make your eyes water even with the original injectors, now it was possible to get close to the tailpipe without gagging.

Tim Benton

iTrader: (1)

back from the dead for people to use.

Tim

RX794

I wish Ralph from Xcessive Motorsports(http://xcessive-motorsports.com/) would add some of his knowledge to this thread, he knows ALOT about how this works and why. His member name on the forum is Xcessive I believe.

Boostn7

here's my findings....

Last few days been tunning my car w/datalogit (thanks RX794) and since I'm running 4x 850cc injectos I started messing with lag time....
My idle has always been rich, low 11's A/F (FJO) but rock solid @ 850rpm....I changed my lag time from .04 to -.10 and -.12 and idle so much smoother !!!! well the FJO showed A/F had gone leaner (11.6-11.9). When I started tunning I realized my accelaretions were much leaner !!!! as I changed the lag time back to original my accelarations were richer.
So for now I back to .04 lag time til everything else is tunned.

FYI: With 4x850cc I've menaged to have 17psi(stock twins) or 1.12kg/cm2 on PowerFC/FCEdit logs with A/Fs in the low 11's and Inj duty hitting 92-94%
Car will soon see a dyno.

SPOautos

John - Was there not a setting between .4 and .-10 that still helped with the idle and didn't lean out the acceleration to much?

What about adjusting the injectors to .-10 for idle them playing with the acceleration factors to make up for the lean acc?

STEPHEN

Boostn7

Stephen,

Yes, by setting lag to -.10 which helped w/ idle and by adding fuel to the accelaration #'s it did help quite a bit.
But some more fuel was needed to be added on the base map in columns N3-N5 under 'til it hit "0" psi.

I went back to original settings 'til I have more time to datalog few runs..

Boostn7

Stephen,

Yes, by setting lag to -.10 which helped w/ idle and by adding fuel to the accelaration #'s it did help quite a bit.
But some more fuel was needed to be added on the base map in columns N3-N5 under 'til it hit "0" psi.

I went back to original settings 'til I have more time to datalog few runs...

Xcessive

I am going to throw a winger in here. I found from trial and error that 850cc @83% & -.40 works great on my car. I tried all type of combos up and down with the figures even going to -.9 and 60% etc.
Why I dont know?

Badog

I still have my temperature lab/experiement hooked up under the hood.

We had a thread about this early on in the Datalogit group and this forum. Net result is the stock IAT is slow acting and is directly affected by the medium it is in. Reaction time is affected down to the limits of the IAT sensor. You can go from never seeing a change in IAT at the sensor in the UIM, to actually seeing a temperature drop coming off of a 5 minute heatsoak idle into a 30 seconds later cruising at 70 MPH.

Most high HP cars have adjusted for this. While mine is no where near "high HP", taking the IAT into the a pre-TB location has had significant advantages in tuning.

Back on topic, I have not played with lag settings at all.

Tony

Ranzo

Hmm I thought it was common knowledge that lag time was needed because of the slower moving larger injectors. The ECU will send the signal earlier or later according to that setting. a + would send the signal earlier for larger injectors and a - signal would send then signal later for smaller injectors.

These settings might change your o2 sensor readings because the injector will start firing earlier (+setting) in the cycle wich might not be on target for your ignition timing causing all the fuel not to be burned properly. The same could be said about a negative setting and so on. I this will not change the overall amount of fuel being delivered because you are not changing the pulsewidth, you are changing when it starts.

Dragon

for those of you running 1680 cc injectors in your secondary's you will want to run +.46 in the secondary MS injector settings. Me and a friend of mine, after tons of playing with them in diffrent cars with diffrent ports etc. have found this # has worked great. Also any one using weird size injector combinations PM me if your using the datalogit and I can probably hook you up with the settings you'll neet to get your injector change over to happen smootly as well since I've been doing a **** load of diffrent combinations of them on customers cars. I'm currently running stock 550's in the primarys and 1680's in the secondarys paired with 2 x 720cc injectors that come on line with the secondarys in the primary runners for a total of 5900cc's of fuel and I've got it running smother than a baby's *** while boosting 24psi with water injection a T70 and huge side port/ex port. After 15 runs my highest knock reading was 17..

twokrx7

iTrader: (1)

17 knock ... water injection is the sh*t.

Dragon