GooRoo

iTrader: (4)

Have a PFC and was trying to lean out my map in the vac ranges today. Using TE wideband and datalogit.

The issue is that at 2400 rpm and nearly any pressure the car goes way way lean. Like 17+ AFR. The only way to get it down is to add 25%+ fuel to the cell and 10% to those around it. Seems to me like this is a hack, and there must be something else wrong.

Fuel pressure is good. Injectors are new 160lbs in the secondaries, and freshly cleaned/tested 850's in the primaries. Motor has moderate to aggressive street port and I'm running a 35r kit from a-spec. The wiring harness was completely dissassembled, cleaned, tested and rewound over the winter. ECU was bought used from a forum member.

Can anyone come up with something that would cause this? So far Damian and I have come up with ECU failure or wierd injector problem, but both seem unlikely. What are we missing? TIA

cewrx7r1

iTrader: (2)

Most likely the point where the secondaries are coming online too lean.
That means your transistion for the secondaries is not set up properly.

GooRoo

iTrader: (4)

I thought the transition was at 3800?

crazyrx7

Its closer to 3000rpm; hense the 3000rpm hesitation on most stock fd's.

R.K.

GooRoo

iTrader: (4)

Ah ok, I've read about that, but my car never has had it.

Aparently I need to read/search more about the transition then. Thanks.

twokrx7

iTrader: (1)

Did you setup the injector settings for the larger injectors? Pri/Sec transition, lag, size, and injector overlap?

GooRoo

iTrader: (4)

I am running the map from Damian's track car currently, and he has the same fuel system as me. The exception to that is he has top feed 720's for primary injectors, whereas I have 850's in the stock rail.

The map I originally got from Steve Kan for my car had some of these settings the same and some different, but the 2500 issue was evident there as well.

What I'm running off Damian's Map

Inj:
Front Primary: 75 0.35
Front Secondary: 0.40
Rear Primary: 75 0.35
Rear Secondary: 0.40

Q Primary 850
Q Secondary 1600

Pri/Sec transition (%) 40.0
Sec transition (ms) 1.000


Inj Overlap:
Boost Setting
14848 7
9984 7
4864 2

cewrx7r1

iTrader: (2)

Try 7-7-4 for overlap.

GooRoo

iTrader: (4)

Update, tried different overlap, pri/sec transition, and sec transition numbers. No effect. Also swapped in another ECU from a friend that was brand new. No effect.

I have a hard time believing this is a transition problem since it's so rpm dependent... Is there something I'm missing there? I thought the last gasp transition (at low low load) would be at 3800rpm. Also if I accelerate very very slowly it goes lean only a small amount.

pluto

The only thing I could think of is that your 1600cc injectors are really not 1600cc injectors. I'm don't see why your car would run that lean on a map that was tuned with the same setup in a different car. Even though the car isn't tuned, but it shouldn't be more than 5-8% more at most.

GooRoo

iTrader: (4)

Additional information: Tuned a bit more last night and got my vaccuum numbers up to near 14. Idle is still somewhat ugly and the 2400 issue is still there even with 15% more fuel than the surrounding cells.

Here's a log of the wideband. I tried to hold about 0in vac in 4th from 1500rpm to 4000. The relevant portion of that is here.

Screenshot of datalog

Column G is the wideband, column B is inj duty. You can see as it starts to go lean the injector numbers jump up a bit as I try to add fuel, then they level off as it accelerates past the hesitation and my added fuel goes back to normal.

GooRoo

iTrader: (4)

The map you gave me is way lean everywhere so I'm not using it anymore. I'm not sure what the 1600's would have to do with that since they aren't even on in most of the vac cells I'm talking about?

Right now I'm using the map you gave D for his track car, and leaning that to fit my car. That is working much better for me, since it started out pig rich (9-10 AFR) and now I have it to 13.5-14 in most of the vac cells. At 0 boost it's getting closer to 12-13 as I haven't really touched any of that since I'm still breaking it in. I need 70 more miles and I will be at 500 and I can start to go minimal boost and see what happens there.

I do agree that it seems there is something mechanically or electrically wrong for this to happen. But I'm not sure what it is yet.

pluto

The 7-7-4, 7-7-2 number that kyle recommended you adjusting correlates on how much overlap between the primary and secondary. The higher the number, the more the secondary overlaps with the primary. The first # is in the vacuum, the 2nd # is at 0psi, the 3rd # is at 7.5psi. Another thing to test is to set those #'s to 0 and see what happens (not to boost of course). I never tried this before so I could be totally off but the logic make sense from the overlap point of view.

GooRoo

iTrader: (4)

I experimented a bit with those yesterday Steve. I had the default 3-2-1, the ones from D's map, 7-7-2, a modification suggested here, 7-7-4 and I also tried 9-7-5 which was posted elsewhere on the boards. None of those changes seemed to make any difference.

I left it at 7-7-4 just because that seemed to be the consensus.

GooRoo

iTrader: (4)

Ok, I may have found something interesting here... I'm looking at the InjFS(mS) in my datalog and it never goes above zero. Unless I'm mistaken the secondaries should have come on by 4k rpm at near 0 in of vac.

Check it out:
2005-8-14-0in-vac-4th-pull.txt

GooRoo

iTrader: (4)

Just to update, my last post was way off, since I had the transition set to 40% the duty never got high enough to turn the secondaries on.

I still have the flat spot at 2400. I'm pretty sure at this point it's not the ECU since a similar one swapped in did the same thing, and I'm pretty sure it's not the ignition, since that would make it go rich, not lean.

I'm trying to avoid it, since it's a pain, but maybe I need to try different injectors?

On the plus side I made it to 1500 miles so I'm broken in, and can do whatever rpm/boost testing I need to do.

Howard Coleman

iTrader: (6)

i was looking over the thread as i have a transition problem also... around zero p10 thru 8 psi p15 i have to jump my fuel almost 50% from one N cell to the next to maintain proper afr. i do think it is a pri/sec transition setting. as to which one, well i am working on it.

just one thing w your situation. i believe you are running 850/1600. why is your primary set at 75? shouldn't it be 550/850 or approx 64.5? also your lag values are quite diff than the norm of .04 and .14.

i do realize that others run somewhat different numbers. i run different numbers on my front and rear rotors to balance egts. yours seem to be quite a bit away from the norm. i realize this probably doesn't relate to your problem.

if i figure out how to smooth out my fuel i will post it..

good luck,

howard coleman

GooRoo

iTrader: (4)

You are right Howard, the primary was set oddly in the numbers I posted above. I was just using what was on Damian's map. I have since changed them on my development map (which I haven't put on the car yet) to 64.5 and I did also switch the lag to .04 for primary and .05 for secondary. Where did you get the .14 number for the secondary from? I have the standard 160lb top feed secondaries that most people have and I thought the manual used those as an example at .05

I need to get Damian's wideband up and running again (had sensor failure on the way to MRR) before I'm willing to switch to that new map. It might make a difference, it might not.

I am still not convinced this is a transition issue since according to my logs the secondaries are not turning on at 2400 rpm, and that is always exactly where I go lean. Is there something I'm missing there? I now have the pri/sec transition % set to 40 and the sec transition (ms) set to .796

cewrx7r1

iTrader: (2)

[QUOTE=GooRoo]The issue is that at 2400 rpm and nearly any pressure the car goes way way lean. Like 17+ AFR. The only way to get it down is to add 25%+ fuel to the cell and 10% to those around it. Seems to me like this is a hack, and there must be something else wrong.
/QUOTE]


Post your fuel base map after a recalc so we can actualyl see the fuel cell times.

GooRoo

iTrader: (4)

Here's the base map after a re-calc on the map I'm currently running. I have a different map ready to go, however the wideband sensors we had died so I'm waiting for one of those to try it out.

This map has the problem at 2400 tuned down to a hesitation. The AFR's go to about 15 or so.

kevinbtz

iTrader: (4)

have you checked to make sure your fuel pulsation dampner is working?

GooRoo

iTrader: (4)

I don't actually have one anymore, I have the KG parts modified primary rail, top feed secondary rail, and a Aeromotive FPR.

kevinbtz

iTrader: (4)

I have heard before that if you do not have a fpd that when your fuel pump and injectors are pulsing in rythem you will go lean.

GooRoo

iTrader: (4)

True, but the Aeromotive FPR is supposed to also show some FPD characteristics.

The other thing is that I can add 30% more fuel in at 2400, thereby changing the injector pulsing quite a bit, and it will still go lean on the wb.

GooRoo

iTrader: (4)

Just an update, I am now running on my changed map (since the wideband is back working) and there have been significant changes.

My idle has cleaned up some.
I had to add all the fuel back in (nearly to 1.0 on the inj map from Damian's Track car map) because of the changed injector lag times/other settings.
I have a slight 1600rpm stumble as well as the 2400 one.

My current theory is that the car is not actually lean, it's that the gas is going unburned because of a ignition problem. I put in Sam's twin power and it didn't seem to do much either way. It did clean up some of the high rpm vibration I was having.

I'm going to try adding some grounding wires to various places and see if that has any effect. If that doesn't work I'll probably have to try different injectors and see what happens.