Fuel injection? Open or Closed loop? - Page 9

Alan Roehrich · 02-05-2017, 12:27 AM

Longest lasting I've ever seen were the sensors that came with the NGK PowerDex kit. Things were tough enough to go about two years, on C-12, maybe 350-400 passes. Lasted until a huge wheelstand got them and the collectors they were in.

Ed Wright · 02-05-2017, 06:31 PM

Since I got my Stahl headers, that isn't near the problem. They are tucked up closer to the floor than the Hedman Hustlers. Oil pan will hit before anything else now. They should all be built like Stahl stuff. I could not find 1 7/8" headers from anybody but Hedman before Stahl. I tried to order a set from Jere originally, but he had no jigs for the 4th gen F body until Woodro took his up there. Jere told me "Just bring the car, we will build them on the car." Just a short jog from Tulsa, OK, to York, PA. Shorter tow for Woodro. Thanks Woodie! LOL

cmracing · 02-06-2017, 09:58 AM

I get about 200 or so passes on an NTK sensor using unleaded race fuel, sometimes more. This is with the Holley system. The Bosch sensor is about half that. If you limit your correction to +-5% or less, then if a sensor does go south, it won't kill the tune that bad. But, you do have to look at your datalogs and keep an eye on things....... I run Closed Loop in both of my cars, but also limit what I allow it to do.

Ed Wright · 02-06-2017, 12:36 PM

I agree. I would never allow it to make more than 5% correction. NTK sensors are great.

Darrel Goheen · 02-06-2017, 12:48 PM

Thanks for the info.!

Sean Marconette · 02-06-2017, 03:05 PM

Thanks as well for the information.

Ed are you planning on racing at the Topeka National open in May?

Sean

Ed Wright · 02-06-2017, 03:33 PM

Quote:

Originally Posted by Sean Marconette

Thanks as well for the information.

Ed are you planning on racing at the Topeka National open in May?

Sean

I don't know, Sean. Jeanie says I'm done. Says I'm too old to be going off like that. Still in discussion. LOL I will if I'm still racing. No AHFS at those. :-)

On the closed Loop thing, The RPM vs Load tables, for + & minus fuel correction limits, I have +4 & -4 percent in the top few cells at 6400, nowhere else. No cells above 6400.
Won't correct on the 2 step or return road. Or, 5600 & down. My converter hits at 6200/6300.

pbp1 · 03-21-2017, 06:58 PM

Neither closed or open loop offer a performance advantage. In a properly set up and tuned Speed Density system, closed loop is just a tuning tool to help guide the building of your VE table, which is simply an airflow model of your engine.
I am not satisfied until the O2 correction is less than + or - 2%. At that point, your VE table is properly calibrated and you should be able to put it in open loop and the engine will perform the same.
The argument that one mode has a performance advantage over the other is completely invalid.
As for the durability of sensors, NTK is the best, and while the NTK sensor is an upgrade on some systems, it is STANDARD EQUIPMENT with the FAST XFI, always has been.
It is basically a personal choice, running in closed loop offers some protection in the event of injector or fuel system failure. The other side of that is if the O2 fails or if you develop a leak in your header, you are going to have a rich condition as a result. Live by the O2, Die by the O2.
As for it being a good or bad idea, two of the top 5 qualifiers in Super Stock at Indy last year were running Closed Loop (and Speed Density) including the #1 qualifier.

The purpose of closed loop IS NOT to correct for changes in air. Speed Demsity does that automatically and in Alpha-N, the tuner does that manually when needed.

The biggest issue that people experience when trying to run in closed loop is the correction overshooting, and then see-sawing up and down. There are gain controls and corrrection limits that you can use to get the "speed" of the correction dialed in for your application to prevent over/under correction. It also works better as you get your base numbers closer so it doesn't have "so far to go".

pbp1 · 03-21-2017, 07:04 PM

On the location of the O2, it will definitely read leaner in a slip fit collector than it will in a primary even at higher TPM and under load, but it takes having 8 O2s plus one in each collector to see that. I have seen an average of one point leaner reading in the collector.
This doesn't mean that the collector is not an OK place for the sensor, you just need to know that and set your A/F targets accordingly.

At the end of the discussion, all that matters is that you find what A/F reading makes your car run the best no matter where you put the sensor.

cmracing · 03-21-2017, 10:27 PM

Quote:

Originally Posted by pbp1

on the location of the o2, it will definitely read leaner in a slip fit collector than it will in a primary even at higher tpm and under load, but it takes having 8 o2s plus one in each collector to see that. I have seen an average of one point leaner reading in the collector.
This doesn't mean that the collector is not an ok place for the sensor, you just need to know that and set your a/f targets accordingly.

at the end of the discussion, all that matters is that you find what a/f reading makes your car run the best no matter where you put the sensor.

amen!

View Poll Results: Fuel injection? Do you run in open loop or closed loop
Open Loop	77	66.38%
Closed Loop	39	33.62%
Voters: 116. You may not vote on this poll

02-05-2017, 12:27 AM	#81
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,930 Likes: 1,003 Liked 1,079 Times in 282 Posts	Re: Fuel injection? Open or Closed loop? Longest lasting I've ever seen were the sensors that came with the NGK PowerDex kit. Things were tough enough to go about two years, on C-12, maybe 350-400 passes. Lasted until a huge wheelstand got them and the collectors they were in. __________________ Alan Roehrich 212A G/S

02-05-2017, 06:31 PM	#82
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 389 Times in 168 Posts	Re: Fuel injection? Open or Closed loop? Since I got my Stahl headers, that isn't near the problem. They are tucked up closer to the floor than the Hedman Hustlers. Oil pan will hit before anything else now. They should all be built like Stahl stuff. I could not find 1 7/8" headers from anybody but Hedman before Stahl. I tried to order a set from Jere originally, but he had no jigs for the 4th gen F body until Woodro took his up there. Jere told me "Just bring the car, we will build them on the car." Just a short jog from Tulsa, OK, to York, PA. Shorter tow for Woodro. Thanks Woodie! LOL __________________ Ed Wright 4156 SS/JA Last edited by Ed Wright; 02-05-2017 at 06:37 PM.

02-06-2017, 09:58 AM	#83
cmracing Member Join Date: Aug 2016 Posts: 173 Likes: 113 Liked 62 Times in 29 Posts	Re: Fuel injection? Open or Closed loop? I get about 200 or so passes on an NTK sensor using unleaded race fuel, sometimes more. This is with the Holley system. The Bosch sensor is about half that. If you limit your correction to +-5% or less, then if a sensor does go south, it won't kill the tune that bad. But, you do have to look at your datalogs and keep an eye on things....... I run Closed Loop in both of my cars, but also limit what I allow it to do.

02-06-2017, 12:36 PM	#84
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 389 Times in 168 Posts	Re: Fuel injection? Open or Closed loop? I agree. I would never allow it to make more than 5% correction. NTK sensors are great. __________________ Ed Wright 4156 SS/JA

02-06-2017, 12:48 PM	#85
Darrel Goheen Member Join Date: Jan 2011 Location: Hays, KS Posts: 379 Likes: 226 Liked 70 Times in 31 Posts	Re: Fuel injection? Open or Closed loop? Thanks for the info.! __________________ Darrel Goheen 785-623-7021 Stock Eliminator 585 94 Camaro Z/28 LT1/ET 585 67 Chevelle 427 Tehnician for JustAnswer.com

02-06-2017, 03:05 PM	#86
Sean Marconette Senior Member Join Date: Mar 2006 Posts: 960 Likes: 629 Liked 167 Times in 61 Posts	Re: Fuel injection? Open or Closed loop? Thanks as well for the information. Ed are you planning on racing at the Topeka National open in May? Sean __________________ Sean Marconette 84 Mustang 5060 SS/N

03-21-2017, 06:58 PM	#88
pbp1 Junior Member Join Date: Mar 2013 Posts: 78 Likes: 11 Liked 18 Times in 5 Posts	Re: Fuel injection? Open or Closed loop? Neither closed or open loop offer a performance advantage. In a properly set up and tuned Speed Density system, closed loop is just a tuning tool to help guide the building of your VE table, which is simply an airflow model of your engine. I am not satisfied until the O2 correction is less than + or - 2%. At that point, your VE table is properly calibrated and you should be able to put it in open loop and the engine will perform the same. The argument that one mode has a performance advantage over the other is completely invalid. As for the durability of sensors, NTK is the best, and while the NTK sensor is an upgrade on some systems, it is STANDARD EQUIPMENT with the FAST XFI, always has been. It is basically a personal choice, running in closed loop offers some protection in the event of injector or fuel system failure. The other side of that is if the O2 fails or if you develop a leak in your header, you are going to have a rich condition as a result. Live by the O2, Die by the O2. As for it being a good or bad idea, two of the top 5 qualifiers in Super Stock at Indy last year were running Closed Loop (and Speed Density) including the #1 qualifier. The purpose of closed loop IS NOT to correct for changes in air. Speed Demsity does that automatically and in Alpha-N, the tuner does that manually when needed. The biggest issue that people experience when trying to run in closed loop is the correction overshooting, and then see-sawing up and down. There are gain controls and corrrection limits that you can use to get the "speed" of the correction dialed in for your application to prevent over/under correction. It also works better as you get your base numbers closer so it doesn't have "so far to go".

03-21-2017, 07:04 PM	#89
pbp1 Junior Member Join Date: Mar 2013 Posts: 78 Likes: 11 Liked 18 Times in 5 Posts	Re: Fuel injection? Open or Closed loop? On the location of the O2, it will definitely read leaner in a slip fit collector than it will in a primary even at higher TPM and under load, but it takes having 8 O2s plus one in each collector to see that. I have seen an average of one point leaner reading in the collector. This doesn't mean that the collector is not an OK place for the sensor, you just need to know that and set your A/F targets accordingly. At the end of the discussion, all that matters is that you find what A/F reading makes your car run the best no matter where you put the sensor.