ct9a_mr

iTrader: (46)

I have been playing around with the injector latencies to get my car not to studder under low RPM. It does this between 1500 and 2500 rpm and is really annoying when taking off from a light. I basically have to rev it to leave smoothly.

I have logged the car with mitsu logger but the low fuel trims never move off 0.
I have tried adjusting the latency below 11v by lowering the values and it does help but I still don't see the fuel trim changing and if I go too low the car shuts off a idle I assume due to the lack of fuel.

I read that below 11v is where I need to adjust, but I also read that with large injectors you need to increase the latency to get them open so I am basically confused.

Currently my injector latency is below with an injector scaling of 860.
Volts Latency
4.6875 2.904
7.03125 1.176
9.375 1.056
11.7188 1.104
14.0625 0.84
16.4062 0.504
18.6768 0.24

I am running FIC 1000cc injectors with FP cams that have -10 vac at idle which I believe is causing the ecu to run into the lower latency tables.
Or the cams are adding much more air at idle and I need to add more fuel to compensate.
Idle is set at 900rpm but I plan to bump it to 1000 tommrow.

I have tried some other recommendations on here for FIC 1000cc injectors but they don't seem to work well in the low rpm for my setup. The upper rpm is clean and smooth (above 3k).
The boost is turned down on my car since I know adjusting this will affect the entire map and I have no wideband.

The intake is BR filter on an injent pipe currently but I had a different K&N on there before and my maf scaling has not been readjusted from the old K&N settings.

Thanks for any help you can provide.

sabastian458

iTrader: (25)

I am very interested to know as well. I have BC280's and I have the same issue. My fuel trims will not move off .1008

mrfred

iTrader: (50)

For latency, all that matters is the voltage. When the car is running, the voltage should be somewhere between 13.5 V and 14.5 V. The latency entry that will have the most effect is the value corresponding to 14.06 V. I just finished measuring an FIC 1050 injector and came up with a value of 0.63 ms at 14.1 V. Your value of 0.84 ms is pretty close. If lowering the latency down to 0.7 ms doesn't improve things, I'd say the problem is not with latency.

Jack_of_Trades

iTrader: (17)

Check your open loop tables and make sure the load values are above 80-85 in the lower load areas and try to log the problem while its occuring along with your wideband readings. This problem is usually a lean mix or modified timing in your lower rpm/load cells.

ct9a_mr

iTrader: (46)

Mrfred I will try adjusting it down to see if I can get the fuel trims to trigger.
Logically the 14v should be the one to make the most different and per my mr voltage gauge since the car is running 14v at idle.
But changing the latencies below 14v seem to make the most difference.

I will keep plugging away with my trail and error method. I am just trying it close and get rid of the studder since the car will be going to TTP to get the final tune.

Jack I don't have a wide band so I am just making adjustments based on mitsulogger and evoscan.

Thanks for the help so far.

ct9a_mr

iTrader: (46)

Jack, I checked the tables and they are where they should be.

I was able to finally get the trims to show up in mitsuloger witht he following settings, but I am not sure where to go from here still it is still studdering but a lot less.

Volts Latency
4.6875 2.904
7.03125 0.912
9.375 0.864
11.7188 0.624
14.0625 0.696
16.4062 0.408
18.6768 0.264

Low fuel trim is showing a contast -2 and the Mid is showing -4.
I have not driven it yet to see what is being transfered over to high.

dan l

iTrader: (3)

The FIC 1000's are different than the newer FIC 1050's. They changed suppliers. Try the following only for FIC 1000's. Also via your trims you don't have enough latency.

4.512
2.568
1.608
1.296
1.104
1.008
0.912

RazorLab

iTrader: (8)

dan, if it's negative trims he needs less latency.

negative = too much fuel = take away latency
positive = too little fuel = add latency

dan l

iTrader: (3)

My bad, brain fart........

erioshi

One trick I used to help with my P300 problem & driveability issues was to change the base injector size and then rework the latencies. My car is running 1000 cc injectors & e85 so YMMV, but here's what I found.

Initially I had the injectors scaled at 609 cc with latencies near the recommended settings. The car ran OK but I still had P300, idle drop & low speed surging problems - nothing critical but the car didn't feel right. Next I tried rescaling the injectors to 622 cc & reworked the latencies. The car ran a bit better but still wasn't right.

Eventually I got really tired of the problems & experimented with a wide variety injector sizing & latencies and ended up with the best driveability, stock like idle, no more P300 issues & no more idle-drop problems with my injectors scaled for 780 cc with latencies that I worked out through trial & error. The car now runs almost exactly like stock except for the extra go I have from the green, cams, e85, etc.

<rant>
For me the big win is NO MORE P300 CODES! My car threw them ever since I first added cams. I tried a bunch of different tricks, but none of them worked until this. The driveability is a huge win for me as well.
</rant>

ct9a_mr

iTrader: (46)

Thanks for the insight guys and I will definitly give your settings a try.
I did forget to mention that the injector size scaling is now down to 812 as well.

ct9a_mr

iTrader: (46)

Problem resolved by TTP-E !

The injectors where too big for my setup, Scott hooked me up with some 745's and retuned the car and it pulls great now!
No low RPM studder and I can finally enjoy the cams.

Big thanks to TTP for his troubleshooting and tuning abilities.
Scott is the man!