Trimming too much fuel in closed loop
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
Trimming too much fuel in closed loop 427 DART block with a 244/254 cam.
Open loop is pretty good but in closed loop it trims too much fuel off both banks and causes a bad stumble under load and the car goes super lean on the wideband.
Ideas? I'm attaching the scan file and tune.
Open loop is pretty good but in closed loop it trims too much fuel off both banks and causes a bad stumble under load and the car goes super lean on the wideband.
Ideas? I'm attaching the scan file and tune.
That cam won't want to run properly in closed loop with narrowband O2s. Do a hybrid tune where above a certain rpm it goes closed loop and tune the idle timing and AFR based on vacuum.
Launching!
Joined: Dec 2011
Posts: 230
Likes: 73
From: south florida
fwiw, mine idles fine in closed loop with 247/253 cam, as above tune it open loop for best timing and vac and then soften up the corrections. it starts to slip a couple % but i think that has more to do with o2 sensor placement
SD 80s are dirty and I mean DIRTY down at the lower pulsewidths, that is probably more the source of your problem then anything. Otherwise it looks like it idles fine and has decent vacuum and it should have no problem idling in closed loop with that cam. Your transient fueling settings look way off to me though so that may be contributing to your problems, specifically fuel boiling time and no reason to disable transient fuel below 1100 rpms. Otherwise there are plenty of SD setups that need a serious amount of fuel in the higher MAP / lower RPM areas.
SD 80s are dirty and I mean DIRTY down at the lower pulsewidths, that is probably more the source of your problem then anything. Otherwise it looks like it idles fine and has decent vacuum and it should have no problem idling in closed loop with that cam. Your transient fueling settings look way off to me though so that may be contributing to your problems, specifically fuel boiling time and no reason to disable transient fuel below 1100 rpms. Otherwise there are plenty of SD setups that need a serious amount of fuel in the higher MAP / lower RPM areas.
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Joined: Jun 2003
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Since your VE only goes to 105 kPa assume you are NA. But your IFR table appears to be setup for a boost referenced FPR. All of the values are the same instead of sloped.
You might want to check with the injector vendor about which values to use, if you are NA and/or if you have an aftermarket FPR and how to set up it for NA since it's not seeing any boost.
You might want to check with the injector vendor about which values to use, if you are NA and/or if you have an aftermarket FPR and how to set up it for NA since it's not seeing any boost.
Last edited by dlandsvZ28; Jul 20, 2021 at 04:47 PM. Reason: edit content
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Verdad Gallardo Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
Since your VE only goes to 105 kPa assume you are NA. But your IFR table appears to be setup for a boost referenced FPR. All of the values are the same instead of sloped.
You might want to check with the injector vendor about which values to use, if you are NA and/or if you have an aftermarket FPR and how to set up it for NA since it's not seeing any boost.
You might want to check with the injector vendor about which values to use, if you are NA and/or if you have an aftermarket FPR and how to set up it for NA since it's not seeing any boost.
So where in HP Tuners do I make that adjustment to ask it to only go closed loop above 2000 rpm? I did a search for hybrid tunes and can't see this anywhere.
Are you saying that's specific to the 80's? The 60's are rock solid and work like gold. I dont believe idling is the issue. It's the fuel trims in closed loop skewing the AFR due to the size cam. Longtubes, overlap, big injectors, yeah it wont like closed loop at idle with factory narrowband O2's.
Last edited by Gripenfelter; Jul 20, 2021 at 09:24 PM.
So where in HP Tuners do I make that adjustment to ask it to only go closed loop above 2000 rpm? I did a search for hybrid tunes and can't see this anywhere.
I agree. It idles fine in open loop. Itr's only when it starts to look at the stock O2s that it goes hairy. I just got home. I'll do some datalogging as soon as it stops raining.
I agree. It idles fine in open loop. Itr's only when it starts to look at the stock O2s that it goes hairy. I just got home. I'll do some datalogging as soon as it stops raining.
http://www.silveradoss.com/forums/to...sing-hptuners/
There's a section on big cams in bold that talk about setting it up.
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
Thanks ddnspider.
I'm going to copy and paste it here so we can find it here too.
So this part here: Disable closed loop at idle and part throttle by setting PE TPS vs. RPM to 0 from 0RPM to 1200RPM inclusive. This forces Pe mode at idle (and subsequently Open Loop) and ignores the O2’s
Is he referring to the HOT and COLD tabs under Power Enrich>Throttle?
I'm going to copy and paste it here so we can find it here too.
Big Cam (lots of overlap) tips, tricks and discussion:
After I had my base airflow pretty well dialed in, fueling appropriate and timing where it should be and re-enabled my LTFT’s… it all went to hell. My fuel trims would just dump the max amount of fuel (+25); the motor would shudder, misfire and smell very rich with heavy soot on the exhaust openings. Keep in mind that positive fuel trims are dumped on top of your Power Enrichment at WOT as well and I certainly didn’t want all that extra fuel at WOT. I should have figured this however I didn’t realize it would be this bad. After refusing to believe just the overlap and the headers would cause this bad of a false lean condition (and subsequent maxed + fuel trims), I confirmed I had no air/exhaust leaks. Now I needed to find a way to keep my fueling stable during idle. I figured I had the choice of going full on Speed Density or do a Hybrid Open Loop approach. Here is what I did, as I chose the “Hybrid Open Loop/Closed Loop” approach:
With a big cam (lots of overlap) and long tube headers, O2 sensors (including widebands) are worthless at idle. I had two approaches that I tried. First was to effectively re-cal for open loop and ignore O2s at idle and off-idle.
Disable closed loop at idle and part throttle by setting PE TPS vs. RPM to 0 from 0RPM to 1200RPM inclusive. This forces Pe mode at idle (and subsequently Open Loop) and ignores the O2’s[/b]
Set Pe enrichment to 1.0 from 0RPM to 1200RPM inclusive. This “prevents” any Pe mode fuel enrichment to occur.
Set columns 68*F through 230*F in your OL F/A vs. Coolant Temp vs. Map to 1.00 (one) up to the Map value you saw during your idle scans. For me I have a 1.00 in all cells from column 68*F – 230*F and 20-80 kPa inclusive. (HPT > Engine > Fuel Control > OL/CL > Open Loop > Eq Ratio).
Set Pe enable to a value lower than what you see at idle (look at your previous idle scans), I set mine to 50kPa and see 75-76kPa at idle (HPT > Engine > Fuel Control > Power Enrichment > Power Enrichment Pe Enable tables). In the same group of tables, set the Delay RPM and Enable Torque to Zero. I also made sure there was no “adders” adding fuel such as “Add vs. ECT” and “Add vs. IAT”. Doing all of this ensures you will actually be in Pe Mode and subsequently OL at idle.
Disable STFT Open Loop (HPT > Engine > Fuel Control > OL/CL > Open Loop > STFT Open Loop).
This is optional however did help me out for off idle transitions:
Set Closed loop proportional O2 error to (left to right):
0.06250 0.06250 0.06250 0.06250 0.06250 0.06250 0.06250 0.15479 0.18750 0.21484 0.24023 0.27002 0.27979
Disable DTC codes P0131 and P0151 by setting the code to “3- no error reported” and be sure to have the SES box checked. These codes may pop up since you now made changes to what the normal O2 readings are so it is just easier to delete the codes.
Save the changes and Flash the PCM with the new settings.
.
After I had my base airflow pretty well dialed in, fueling appropriate and timing where it should be and re-enabled my LTFT’s… it all went to hell. My fuel trims would just dump the max amount of fuel (+25); the motor would shudder, misfire and smell very rich with heavy soot on the exhaust openings. Keep in mind that positive fuel trims are dumped on top of your Power Enrichment at WOT as well and I certainly didn’t want all that extra fuel at WOT. I should have figured this however I didn’t realize it would be this bad. After refusing to believe just the overlap and the headers would cause this bad of a false lean condition (and subsequent maxed + fuel trims), I confirmed I had no air/exhaust leaks. Now I needed to find a way to keep my fueling stable during idle. I figured I had the choice of going full on Speed Density or do a Hybrid Open Loop approach. Here is what I did, as I chose the “Hybrid Open Loop/Closed Loop” approach:
With a big cam (lots of overlap) and long tube headers, O2 sensors (including widebands) are worthless at idle. I had two approaches that I tried. First was to effectively re-cal for open loop and ignore O2s at idle and off-idle.
Disable closed loop at idle and part throttle by setting PE TPS vs. RPM to 0 from 0RPM to 1200RPM inclusive. This forces Pe mode at idle (and subsequently Open Loop) and ignores the O2’s[/b]
Set Pe enrichment to 1.0 from 0RPM to 1200RPM inclusive. This “prevents” any Pe mode fuel enrichment to occur.
Set columns 68*F through 230*F in your OL F/A vs. Coolant Temp vs. Map to 1.00 (one) up to the Map value you saw during your idle scans. For me I have a 1.00 in all cells from column 68*F – 230*F and 20-80 kPa inclusive. (HPT > Engine > Fuel Control > OL/CL > Open Loop > Eq Ratio).
Set Pe enable to a value lower than what you see at idle (look at your previous idle scans), I set mine to 50kPa and see 75-76kPa at idle (HPT > Engine > Fuel Control > Power Enrichment > Power Enrichment Pe Enable tables). In the same group of tables, set the Delay RPM and Enable Torque to Zero. I also made sure there was no “adders” adding fuel such as “Add vs. ECT” and “Add vs. IAT”. Doing all of this ensures you will actually be in Pe Mode and subsequently OL at idle.
Disable STFT Open Loop (HPT > Engine > Fuel Control > OL/CL > Open Loop > STFT Open Loop).
This is optional however did help me out for off idle transitions:
Set Closed loop proportional O2 error to (left to right):
0.06250 0.06250 0.06250 0.06250 0.06250 0.06250 0.06250 0.15479 0.18750 0.21484 0.24023 0.27002 0.27979
Disable DTC codes P0131 and P0151 by setting the code to “3- no error reported” and be sure to have the SES box checked. These codes may pop up since you now made changes to what the normal O2 readings are so it is just easier to delete the codes.
Save the changes and Flash the PCM with the new settings.
.
Is he referring to the HOT and COLD tabs under Power Enrich>Throttle?
Are you saying that's specific to the 80's? The 60's are rock solid and work like gold. I dont believe idling is the issue. It's the fuel trims in closed loop skewing the AFR due to the size cam. Longtubes, overlap, big injectors, yeah it wont like closed loop at idle with factory narrowband O2's.
The 80's are totally different than the 60's at idle. The 80's are horrible at idle compared to a good injector. We run FIC 2150's in a bunch of builds and I can make them idle like stock in closed loop.
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
In open loop the idle isn't that bad. In the datalog I posted in the original post there was one dip which is out of the norm honestly. It normally doesn't do that.
It was raining yesterday and I'm on MT drag radials so I didn't do any logging. Hoping to do some logging tonight.
I made changes to the tune as ddnspider recommended. In the HOT COLD tabs under THROTTLE I zeroed it out till 2000 rpm. In the EQ Ratio gas table I made everything 1.0 from 0 to 2000 rpm (This equates to stoich as ddnspider mentioned).
Let's see how that works.
The other issue I'm having is I never see knock because I'm using ICT Billet relocation blocks. They desensitize the sensor too much. So I'm debating either increasing the gains on the KNOCK SENSOR GLOBAL GAIN table by doing the following or just simply drilling the block and mounting the knock sensors directly to the block:
It was raining yesterday and I'm on MT drag radials so I didn't do any logging. Hoping to do some logging tonight.
I made changes to the tune as ddnspider recommended. In the HOT COLD tabs under THROTTLE I zeroed it out till 2000 rpm. In the EQ Ratio gas table I made everything 1.0 from 0 to 2000 rpm (This equates to stoich as ddnspider mentioned).
Let's see how that works.
The other issue I'm having is I never see knock because I'm using ICT Billet relocation blocks. They desensitize the sensor too much. So I'm debating either increasing the gains on the KNOCK SENSOR GLOBAL GAIN table by doing the following or just simply drilling the block and mounting the knock sensors directly to the block:
multiply the entire table by .9 at at time to increase the knock sensor sensitivity until spark knock is seen with sensible spark timing, then increase the table by 5%.
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
Here is the latest tune and data logs. Less stumbling under load but car wants to stall more. I'm going to play with the timing this weekend.
Anything else you guys think I should change?
Not sure why the wideband isn't working. Might be a broken wire somewhere. Gauge works fine. I'll take a look tonight.
It stumbles a bit when you first hit the gas and the wideband jumps to 17 but half a second later it's fine.
Anything else you guys think I should change?
Not sure why the wideband isn't working. Might be a broken wire somewhere. Gauge works fine. I'll take a look tonight.
It stumbles a bit when you first hit the gas and the wideband jumps to 17 but half a second later it's fine.
Last edited by Gripenfelter; Jul 22, 2021 at 04:58 AM.
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
It feels like it needs more air. I'll take a look. I think my TB screw backed out. My IAC counts are up again around 110 instead of 40-60.
Last edited by Gripenfelter; Jul 22, 2021 at 03:19 PM.
Deka Siemens 60's are the gold standard for fuel injectors. In the last decade before or after them I have not seen anything that can compare for fuel flow, repeatability, or range of useable fuel pressure. Almost every competitor has at the very minimum idle problems, and on the other end high pressure lockup. It seems that we should have something better all these years later.
Deka Siemens 60's are the gold standard for fuel injectors. In the last decade before or after them I have not seen anything that can compare for fuel flow, repeatability, or range of useable fuel pressure. Almost every competitor has at the very minimum idle problems, and on the other end high pressure lockup. It seems that we should have something better all these years later.