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Ok,
first the specs and background..
L-31 crate motor / LT4 hotcam /1.6 rocker arms
Stock TPI upper / Edelbrock large tubes / SD lower vorteq TPI
52mm throttle body
Bosch III red 30lbs. injectors - BPW adjusted...
EBL P4
I'm attaching my initial tune and data log, and the last one I did today. I've been having some surge problems, but increasing the fuel pressure seems to have improved the situation quite a bit. The one thing I can't figure out is how to get the steps up to ~10 or so at idle. I followed the method on zeroing the IAC and pulled the connector, and set the base idle to around 700rpm.
Couple questions:
1. How to get the IAC counts up?
2. Is there anything I'm missing that you guys can see that would contribute to idle surge? It's a bit better, but not great.
Need to increase the idle speed in the BIN. It is currently at 550 RPM, which is way too low for that cam. Try a 750 RPM idle at regular engine coolant temperature, which means to add 200 RPM across this table:
IAC - Idle Speed: Drive
Will also need to work on the VE table at the low RPM and high MAP area. See the only images on this page for what to do:
ok, so I did that... it helped some, and I ran a few more VE runs.
I attached two datalogs
first one is (fan on3.dat)
open loop idles 750~850 rpm, and seems fine until closed loop
closed loop starts at run time of 1:06 surging from 630~960rpm after a while it settles down to 630~900rpm.
At run time of 4:54 you can see the fan kicked on and the voltage changes from 13.7v to 13.2v, then the surging increases from 575~1000 rpm.
I'm not sure why the initial surging, but the voltage change may be because the injector correction offset chart might be off a bit with the larger injectors???
The second datalog is (after gas up ve run.dat) longer driving run. I'm wondering if there is anything that looks unusual to anyone. The IAC steps seem a bit strange to me, they climb up to over 100 steps. Is this normal?
I also added the bin file, its coming together, probably needs more smoothing.....
OK, the idle surging is from not enough proportional gains. Open this parameter:
PRP - Gain Multiplier for Idle (Airflow)
And set it to 25%, see if that does the trick. May need to tweak it from there. Also be sure to grab the latest XDF file from our web site. There are some corrections to the idle proportional gains conversions.
OK, the idle surging is from not enough proportional gains. Open this parameter:
PRP - Gain Multiplier for Idle (Airflow)
And set it to 25%, see if that does the trick. May need to tweak it from there. Also be sure to grab the latest XDF file from our web site. There are some corrections to the idle proportional gains conversions.
RBob.
Ok ill try that. Im already using the latest .XDF
The prp gain multiplier was set to .78
Should that number be .25 or 25?
I set it to 25 for now...
The Idle surge (oscillation) is now maybe 75% improved, but still present...
Today I worked on the idle and started with the PRP gain multiplier. I tried tweaking the % and watching RPM oscillation amount at each %. I'm not exactly sure what all to watch, but what I did was run 3 minute datalogs with the engine warm and closed loop. I tried 21/23/24/25/27% runs and output each datalog into a .csv file and compared RPM's/O2mv/sPw standard deviations in excel. The best situation seemed to be 24% (same as your screenshot).
Then I moved on to duration for idle, originally it was set at 800 mSec, so I tried 200 mSec (like your screenshot), and also 400mSec. I again compared RPM oscillation/O2mv/sPW standard deviations in excel, and 200mSec had again improved the RPM oscillation slightly. I didn't get a chance to try below 200 mSec, as I ran out of time today...
Questions:
1. Is this correct method? Is there something else I should be monitoring from the data logs?
2. Should I just completely copy the tables in your screenshot?
3. If not copy, should I just change the tables by a % increase or decrease?
Thanks for the help! Its coming along.... slowly but surely
When I was TBI and had a larger cam(224/230@.05) I chose to idle OL. Fixed the oscillation nicely. Down side was idle A/F would range from 15.0 to 13.9 day to day depending on under hood air temps and environmental temps. Adding an inlet air temp sensor helped as well. Also locked idle SA at 22 deg.
I looked at your latest log from above, at first the O2 sensor was quite active. But then as time went on it just goes high with some low going activity. Not sure what is going on with the O2 sensor, maybe it is bad.
The idle was quite smooth until the ECM went closed loop. But in closed loop the INT hardly moves, the RPM is jumpy, and even the IAC is getting in on the action.
Need to open the idle stop screw some. Get the IAC step count in the 20 - 25 step range. As you tune the idle in better you may need to readjust the IAC along the way.
The jumpy RPM may be due to too much idle compensation SA. Can reduce it by half in these two tables, see if that helps:
SA - Idle Low Compensation
SA - Idle High Compensation
The other thing is to drive the car a bit, even if just around the block. Get some heat into the engine, exhaust and O2 sensor. Then see how the idle is.
So I had a few things to fix in the last couple weeks, so I've got back to working on the idle problem.
I tried the SA adjustment, and put some miles on it.
Since the SA adjustment, it seems to stall at intersections (holding the brakes)
and the surge still hasn't changed. Ive noticed it actually does it in open loop as well.
Is it possible the fuel pump isn't keeping up? The pressure doesn't seem to be very stable and drops as rpms come up. I haven't been able to find out what it should be (above idle)
It idles at 42~44 and mostly is at 43psi
I'll see if I can get a log of it later
I ran a log, you can see a few stalls in there in the beginning.
I wasn't able to output the fuel pressure into .csv file, apparently that's not an option?
A couple of things, the stalling at idle is being caused by a MAP HI 33 malfunction. The engine is struggling somewhat to run which isn't helping. Increase this value to 80 KPa:
MALF33 - MAP Hi BARO Limit (1bar)
As for fuel pressure, service range is something like 43 to 47 psi. This is done with the vacuum line off. The pressure will vary according to intake manifold pressure, which is normal.
It appears to be set at about 50 psi line off. As for the fuel pressure in the csv file, it was there when I dumped the log. The very last column.
Need to change the BLM cell 2 RPM threshold, make this value 1000 RPM:
BLM - Idle Cell RPM Threshold
That should help with the surging some. But since it also does it in open loop likely need to work the lean area out of the VE table.
OK, I've been fooling with this tune for a few days, and finally started doing WB VE learns. I'm not sure I have this set correctly for VE learns, and or its working correctly. I am still having some issues with idle, not great, but it will do for now.
I selected WB for VE learns in the preferences tab, set the CTS for 151 and set my TT-1 WB filter to 10%. I also set the smoothing factor to 8.
It seems the TT-1 WB is only outputting 14.7 signal until around 7:20 in the datalog??? Is this normal? At key off it drops, but I'm not sure why it doesn't start working from the beginning??? Also is it normal for it to drop out of closed loop so frequently, not sure it looks normal?
I think the VE tables are taking shape, maybe someone could have a look and see if anything looks very odd? I'm hoping someone can give me some direction of how to improve my results...
I did drop the hammer today, and got a backfire pop out of the tailpipe, but so far no knock...
I lowered the cts to 47 for this datalog, to see how it would run in closed loop.
It seems the TT-1 WB is only outputting 14.7 signal until around 7:20 in the datalog?
It should become operational at about 25 seconds after power up. Maybe the sensor is on the way out?
Also is it normal for it to drop out of closed loop so frequently, not sure it looks normal?
Yes, every time you lift or go WOT it will drop out of closed loop. The open loop decel is a flag to enable it. Can unset the flag to re-enable closed loop decel. Note that this is useful for tuning but can also cause surging.
I think the VE tables are taking shape, maybe someone could have a look and see if anything looks very odd? I'm hoping someone can give me some direction of how to improve my results.
The VE tables still need some work but are getting there. Look at them in the TunerPro graph.
Note that there is a fuel delivery issue. See the log at the 7:32 - 7:34 run time area. The lean spikes in the WB data are due to the fuel pressure dropping as low as 14 psi. Can also see the pressure drop in the 7:51 - 7:54 area.
Low fuel level can cause this, along with a poorly baffled fuel tank.
Well thanks once again! I suspected my fuel pump was on its way out so I already had one and a new filter on hand.
Made a big difference in how the truck runs. I noticed that the ve learns were adding some fuel in one learn then taking away in the next... Going in circles.
One question, can I just replace the sensor on the TT1, or do I have to buy the whole unit again?
If just the sensor, is there a part number you can recommend?
Most brick & mortar stores have it in stock. Just ask for a Bosch O2 sensor with the above part number.
Good deal on getting the fuel delivery squared away. A note on truck fuel tanks, they tend to be poorly baffled and run fore and aft. It is easy to create fuel slosh that uncovers the pickup.
Say the tank is down to about 1/2 full. Pull out hard for a second then lift, pause and hit the go-pedal hard, the engine falls on it's face as the pickup sucks air. Just something to be aware of.
[QUOTEI noticed that the ve learns were adding some fuel in one learn then taking away in the next][/QUOTE]
Not uncommon if VE-L are on differing days. After all it is adjusting the VE table to attain stoich which varies on inlet temps, heat sink, atmospheric pressure, etc. If VE tuned for 85dF (128 BLM)and then you drive on a 50d day it will add fuel (raise BLM)and that will appear in a log with a VE correction. I would attempt to attain a smooth transition in VE table rather than chasing perfection in BLM. Been there......... .
It's an 87' Toyota 4 runner, and I forgot to mention I had the fuel pump mounted to the inside of the frame rail...outside the tank.
I was running sand dunes after replacing the fuel pump (inside the tank) and didn't notice any cut out on any of the hills, even down to 1/4 tank. The tank does have a sump well with a 1/2" filler line.
Kinda like this one, slightly deeper though
The adding and removing fuel in ve learn was on the same day within 20 minutes of each other...
I need to run a few learns since the fuel pump change to see the difference, it still has a minor idle surge. I'll see if I can get a new WB sensor this week.
It's an 87' Toyota 4 runner, and I forgot to mention I had the fuel pump mounted to the inside of the frame rail...outside the tank.
I was running sand dunes after replacing the fuel pump (inside the tank) and didn't notice any cut out on any of the hills, even down to 1/4 tank. The tank does have a sump well with a 1/2" filler line.
04-09-2016, 03:32 PM
