I Want Speed Density!

[misterp]

Too late! ...

Wait a minute we're getting lost here - If you go SD on your tune, then you are removing the O2s, and that will allow you to replace one with a WB sensor.

 

(Excuse the lecture but...)

 

There are 2 ways the engine can be fueled, either with the MAF or without the MAF. In the beginning (1980s) when we didn't have MAF sensors the engineers used a trio of sensors and some math to figure out how much air the engine was taking in, MAP sensor, IAT sensor, TP sensor and if you know these variables you can fuel the engine, in theory. You calculate according to gas laws how much air should be entering the motor, and then you add the corresponding amount of fuel... This is called "Speed Denisty" system, also called "Open Loop" and notice that no oxygen sensors are required at all, but your math and the values typed into your PCMs tune had better be spot on. For this reason you need a separate wideband to verify proper fueling of the motor 'cause it's all on you.

 

The second way to fuel a motor is called "Closed Loop" and basically you mount devices on the engine to directly measure the air coming into the motor (a MAF sensor) and for redundancy use oxygen sensors to verify/validate what you are seeing from the MAF. In Closed Loop all you need is the MAF, O2 sensors, and TP sensor; no math because you are actually measuring the incoming airflow. Problem with MAFs is that they don't work at low air velocities (low RPM), are an inlet restriction (well our 78mm one is) and O2 sensors and MAF sensors are complicated and never calibrated right and get dirty and are finiky etc etc so your tune is off a few percent (enough to loose the race).

 

The PCM is constantly switching from open loop to closed loop as you drive, you can watch this in logs.

 

So going OLSD means that you can remove the MAF and O2 sensors; replace the driver's NB one with your WB sensor and guage. If you do I call dibs on your NB sensors.

 

Mr. P.

Edited April 15, 2008 by Mr. P. (see edit history)

[RacerJJ]

Thanks for the help P. So let me get this straight...If I go OLSD, I can eliminate the FRONT o2 sensors, the MAF, and run open throttle body with no CAI?

 

If so, in order to do this, I need will need a WB o2, a guage, and an IAT sensor along with a re-tune correct?

[Justin Lamanna]

Thanks for the help P. So let me get this straight...If I go OLSD, I can eliminate the FRONT o2 sensors, the MAF, and run open throttle body with no CAI?

 

If so, in order to do this, I need will need a WB o2, a guage, and an IAT sensor along with a re-tune correct?

 

yea, quik was running speed density. PM him, he can give you some advice or suggestions.

[mean05]

i would stick with the MAF

Edited April 15, 2008 by mean05 (see edit history)

[sprayed99]

Wait a minute we're getting lost here - If you go SD on your tune, then you are removing the O2s, and that will allow you to replace one with a WB sensor.

 

(Excuse the lecture but...)

 

There are 2 ways the engine can be fueled, either with the MAF or without the MAF. In the beginning (1980s) when we didn't have MAF sensors the engineers used a trio of sensors and some math to figure out how much air the engine was taking in, MAP sensor, IAT sensor, TP sensor and if you know these variables you can fuel the engine, in theory. You calculate according to gas laws how much air should be entering the motor, and then you add the corresponding amount of fuel... This is called "Speed Denisty" system, also called "Open Loop" and notice that no oxygen sensors are required at all, but your math and the values typed into your PCMs tune had better be spot on. For this reason you need a separate wideband to verify proper fueling of the motor 'cause it's all on you.

 

The second way to fuel a motor is called "Closed Loop" and basically you mount devices on the engine to directly measure the air coming into the motor (a MAF sensor) and for redundancy use oxygen sensors to verify/validate what you are seeing from the MAF. In Closed Loop all you need is the MAF, O2 sensors, and TP sensor; no math because you are actually measuring the incoming airflow. Problem with MAFs is that they don't work at low air velocities (low RPM), are an inlet restriction (well our 78mm one is) and O2 sensors and MAF sensors are complicated and never calibrated right and get dirty and are finiky etc etc so your tune is off a few percent (enough to loose the race).

 

The PCM is constantly switching from open loop to closed loop as you drive, you can watch this in logs.

 

So going OLSD means that you can remove the MAF and O2 sensors; replace the driver's NB one with your WB sensor and guage. If you do I call dibs on your NB sensors.

 

Mr. P.

 

 

 

um no offense but why would you only read one bank............you need a wideband to read where the two banks come together..........remember the famous #7 issues in the Gen III/VI engines

[mean05]

um no offense but why would you only read one bank............you need a wideband to read where the two banks come together..........remember the famous #7 issues in the Gen III/VI engines

 

true and if i had only one side to read from being as you need the o2 sensor for the wideband close to the collector i would choose the passengers side...

[misterp]

um no offense but why would you only read one bank............you need a wideband to read where the two banks come together..........remember the famous #7 issues in the Gen III/VI engines

true and if i had only one side to read from being as you need the o2 sensor for the wideband close to the collector i would choose the passengers side...

Because 2 WB's would be like $500! I would monitor the driver's side, as the #5 and #7 plugs are consecutive in the firing order combined with the intake manifold biasing more air to #7 and making it run lean.

 

Mr. P.

Edited April 15, 2008 by Mr. P. (see edit history)

[sprayed99]

true and if i had only one side to read from being as you need the o2 sensor for the wideband close to the collector i would choose the passengers side...

 

Because 2 WB's would be like $500! I would monitor the driver's side, as the #5 and #7 plugs are consecutive in the firing order combined with the intake manifold biasing more air to #7 and making it run lean.

 

Mr. P.

 

which will still not give you the true reading from all 8 cyl. I always run my widebands at the y

[RacerJJ]

which will still not give you the true reading from all 8 cyl. I always run my widebands at the y

What and where is this Y you speak of?

[Holty]

you also have the option to run SDCL (speed density, closed loop) which is what i run. It works very well for me.

[RacerJJ]

you also have the option to run SDCL (speed density, closed loop) which is what i run. It works very well for me.

Explain please!!! I am not 100% familiar with these terms just yet. Thanks...

[chpspecial]

john, this week end I might be helping another SSS member with teh install of the vortech supercharger, I will read up on SD tunning with hptuners to help you out. also you might have to purchase more credits on HPTuners to be able to do it. I have a WB o2 sensor that we can use to tune, its the LM1 so we wont have a problem there and you don't have to purchase one if you don't want to. Another thing is that if you do buy a wb o2, you can use it to simulate a narrow band o2 so that it would replace a stock o2 sensor, and lastly, as mr.p said, I would put the wbo2 senser in the drivers side as that is the side that runs lean, so basically if you can get the driverside tuned to your targeted afr, the passanger will also be there, only slightly richer, but its better to be on the rich side than the lean. Having the wb o2 on the passanger side will cause the drivers side to run slightly leaner, as will having the o2 on the Y of the exhauset system. Idealy having 2 wb sensors would be better, but the banks can not be tuned seperatly, and if you want to be technical having a wb on each cylinder woudl be the best, if not a wb a pyrometer (sp)

[dozer]

um no offense but why would you only read one bank............you need a wideband to read where the two banks come together..........remember the famous #7 issues in the Gen III/VI engines

Bank 1 is famous for being the leaner of the 2 banks so that is the side you put the wideband in. 2 widebands would be ideal but you would still tune using the readings form bank 1 because of it being leaner. The bank 2 wideband would be nice to for it could let you know of a problem but I would not use it to tune. Most of us run dual exhaust so the WB gets put in the Bank 1.

Edited April 16, 2008 by dozer (see edit history)

[RacerJJ]

john, this week end I might be helping another SSS member with teh install of the vortech supercharger, I will read up on SD tunning with hptuners to help you out. also you might have to purchase more credits on HPTuners to be able to do it. I have a WB o2 sensor that we can use to tune, its the LM1 so we wont have a problem there and you don't have to purchase one if you don't want to. Another thing is that if you do buy a wb o2, you can use it to simulate a narrow band o2 so that it would replace a stock o2 sensor, and lastly, as mr.p said, I would put the wbo2 senser in the drivers side as that is the side that runs lean, so basically if you can get the driverside tuned to your targeted afr, the passanger will also be there, only slightly richer, but its better to be on the rich side than the lean. Having the wb o2 on the passanger side will cause the drivers side to run slightly leaner, as will having the o2 on the Y of the exhauset system. Idealy having 2 wb sensors would be better, but the banks can not be tuned seperatly, and if you want to be technical having a wb on each cylinder woudl be the best, if not a wb a pyrometer (sp)

Thanks reynaldo. That would be great to have your help. Why would I need to buy more credits? Can't we just modify my existing tune? I can buy another credit but it's complicated because the system isn't mine so I would have to pay 06vho and he would have to buy them, etc. etc. PM me and let me know when you are free. I am pretty free on weekends for the next month and I am free Monday, Tuesday, and Friday evenings. It would be awsome to have this done within the next two weeks so I can test at the next Fontana Street Legal event. LMK...

[SS_bnoon_SS]

Thanks reynaldo. That would be great to have your help. Why would I need to buy more credits?

 

You don't need to buy more credits to run SD tuning without boost. HPT offers higher resolution tuning files to run 2 and 3 bar SD systems needed for running boost, but you don't need those. You'll be fine on the stock 1 bar sensor.