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    Results 1 to 7 of 7
    1. #1
      Join Date
      Sep 2010
      Location
      Orange County, CA
      Posts
      665

      GM ecu vs aftermarket and PWM control

      I’m trying understand the wiring difference between GMPP (connect and cruise kit) or an aftermarket kit such as Holley (pwm capable sytem) to run a LS3 w/T56. My question is more related to function and wiring hook up, not about additional features or preferences. I would like PWM fan control for sure, and most likely PWM fuel pump. My goal is to keep wiring as simple and direct as possible. So am I understanding this correctly,

      1. GMPP ecu offers no PWM control or signal but PWM can be adapted. I’ve read the entire massive thread on PWM going around here and on the other forum. Or a stand alone PWM controller such as the DCC units, but this takes the ecu fan control out of the loop and runs independently? Does it get temp from ecu or does it require another temp sender?

      2. Aftermarket ecu w/PWM (ie Holley) will provide a signal, but will still need a PWM controller such as the C6 controller? This would be more or less and play?

      3. How about A/C trinary switch, it gets wired in either way so no difference either way?

      4. PWM fuel pump, not as concerned with it as much as I am about PWM fan, but would still like to use it. GMPP ecu then use vaporworx pwm fuel pump controller? Aftermarket ecu still need vaporworx controller, or what other options to hook it up?

      I’m mostly asking about PWM in this post, but as an additional question comparing the different ecu’s, and instead of starting another thread,

      5. GMPP uses 2 - O2 sensors and the Holley (Terminator X for example) only uses 1 - O2 sensors. What are the pros and cons if this, if any?

      6. GMPP uses MAF and Holley uses MAP, correct? I know this can be complicated to answer quickly, but is there any major pros or cons either way? I’ve done a ton of research on this but it seems like it’s a 50/50 mix of opinions. I’m running the LS3 525/ASA cam, if that makes any difference.

      I’ve been going back and forth for a while now if I’d like to stick with factory stuff or go aftermarket, so I’m really looking forward to your opinions. Thanks for the help.

    2. #2
      Join Date
      Jun 2010
      Location
      Deployed
      Posts
      3,280
      Country Flag: United States
      I’m not a fan of 1 O2 sensor with an engine with two separate banks. I’m sure the job can be done with one, and from a marketing standpoint it’s not worth the extra cost. pwm for the fuel pump is more important than the fan. I run the vaporwork and it better IMHO because it’s in the trunk.

      I like my GM E67 ECM. It’s not very large and works fine. The self tuning feature is really all I see to be valued in the Holley, but a dyno tune can’t be replaced for maximum performance.
      1970 Camaro/DSE build


      Are you driver enough? Maybe....come on blue!
      https://www.pro-touring.com/threads/...71#post1147371

    3. #3
      Join Date
      Sep 2010
      Location
      Beach Park IL
      Posts
      2,838
      Country Flag: United States
      You don't use a trinary switch, you use a binary switch and it only functions as a high/low pressure cutout for the compressor. The third function in the trinary is fan control, instead you would use a pressure sensor in the high side of the system and scale your fan control against that.

      Not all fuel pumps will run on pwm, I talked to Carl about using a Dominator to run the fuel pump and at the time he didn't recommend it. I do not remember why, hopefully he chimes in.

      The single O2 bothers me but not enough to keep me from using that system.

      There could be a whole forum about MAF vs SD.......Perfect world, MAF is better for driveability but hot rods are imperfect.
      Donny

      Support your local hot rod shop!

    4. #4
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      4,488
      Country Flag: United States
      pwm fan control is fairly forgiving in that it doesn’t matter much if you have overshoot or undershoot etc in your fan speed.

      PWM of a fuel pump is quite different in that you pretty much need that exact fuel pressure. Overshoot, undershoot, ringing etc is not a good thing. You better know your control loop theory and nail the implementation or your car is likely going to run like crap...

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain
      1959 Apache Fleetside

    5. #5
      Join Date
      Jun 2001
      Location
      Newbury Park, CA
      Posts
      5,821
      Country Flag: United States
      Quote Originally Posted by dhutton View Post
      pwm fan control is fairly forgiving in that it doesn’t matter much if you have overshoot or undershoot etc in your fan speed.

      PWM of a fuel pump is quite different in that you pretty much need that exact fuel pressure. Overshoot, undershoot, ringing etc is not a good thing. You better know your control loop theory and nail the implementation or your car is likely going to run like crap...

      Don
      Fortunately, we've got the control strategy pretty well figured out. Constant, manifold referenced, LSA, etc. is no problem.

      Some of the throttle body type system can sometimes cause an erratic fuel pressure at idle even with the fuel pressure sensor mounted in the rear of the car. It's a combination of injector size and frequency that can cause the fuel pressure sensor in a PWM system to pick up the injector pulses and chase them, causing the erratic pressure. Most of the time the flexibility of the lines and column of fuel have enough affect as a damper. The fix is a fuel pressure damper from Radium Engineering. These can often help even on mechanically regulated systems.

      Tuning of the ECM when using a stand alone PWM fuel pump controller is the same as if it were a return system, so it's easy for any tuner to work with.

      Donny is spot-on about pumps. Some will work well with PWM, some just won't. From an overall packaging standpoint, using the Gen5 Camaro ZL1 fuel module is one of the best overall deals out there. 750hp NA capable, internal filter, surge tank, safety valve, etc. It will drain the tank dry during hard driving on our cars. A single fuel line with no filters, return lines, external regulators, etc. All for about $175. There's really nothing in the aftermarket that is in the same orbit as an OEM fuel module.

      There is a lot to be said about both MAF and SD. Personally, I dig MAF. Some of the well known folks that build big HP cars use MAF. It's not as easy to tune, and placement of the sensor is critical for it to work correctly, but when it's working right it's great. Altitude, heat changes, etc. make no difference in mine.

      How much have the OEM's embraced the MAF? So much so at Ford that the Coyote does not have a MAP sensor.
      VaporWorx. We Give You Gas http://www.vaporworx.com

    6. #6
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      4,488
      Country Flag: United States
      Quote Originally Posted by CarlC View Post
      Fortunately, we've got the control strategy pretty well figured out. Constant, manifold referenced, LSA, etc. is no problem.

      Some of the throttle body type system can sometimes cause an erratic fuel pressure at idle even with the fuel pressure sensor mounted in the rear of the car. It's a combination of injector size and frequency that can cause the fuel pressure sensor in a pwm system to pick up the injector pulses and chase them, causing the erratic pressure. Most of the time the flexibility of the lines and column of fuel have enough affect as a damper. The fix is a fuel pressure damper from Radium Engineering. These can often help even on mechanically regulated systems.

      Tuning of the ECM when using a stand alone PWM fuel pump controller is the same as if it were a return system, so it's easy for any tuner to work with.

      Donny is spot-on about pumps. Some will work well with PWM, some just won't. From an overall packaging standpoint, using the Gen5 Camaro ZL1 fuel module is one of the best overall deals out there. 750hp NA capable, internal filter, surge tank, safety valve, etc. It will drain the tank dry during hard driving on our cars. A single fuel line with no filters, return lines, external regulators, etc. All for about $175. There's really nothing in the aftermarket that is in the same orbit as an OEM fuel module.

      There is a lot to be said about both MAF and SD. Personally, I dig MAF. Some of the well known folks that build big HP cars use MAF. It's not as easy to tune, and placement of the sensor is critical for it to work correctly, but when it's working right it's great. Altitude, heat changes, etc. make no difference in mine.

      How much have the OEM's embraced the MAF? So much so at Ford that the Coyote does not have a MAP sensor.
      Hi Carl. My comments weren’t directed to your controller. I’ve used several of them. I was referring to the idea of using the Holley PWM output to implement fuel pump PWM control.

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain
      1959 Apache Fleetside

    7. #7
      Join Date
      Oct 2011
      Posts
      696
      Since your questioning mostly pwm fan control and if you are looking for the SIMPLEST setup, go with aftermarket PWM fan control such as DCC. It’s simple plug and play and yes they have their own temp sensor which is totally separate from ECU. In order to use ECU as PWM fan control you would need to buy the C6 controller, various connectors, wires, (it is NOT plug and play) then the main thing is activate PWM in ECu and put in the values manually. So you will need a program such as HP tuners to even get in to access those functions. If you can’t do it yourself sure a tuner can do it but I’m sure it will be expensive as it’s time consuming. So value to reward to me is very low considering a DCC unit is under $200 plug and play.

      As far as PWM fuel control again you can try to adapt factory PWM controller but again you would need HP tuners and constantly manually tune the values because none of this stuff is active GMPP ECU. So again going aftermarket with vaporworx is a no brainer. It’s a simple system, plug and play and IT WORKS!



      For me I’m a simple DIY guy not an ex auto tech so for me I need stuff that’s proven to work that’s pretty much plug and play. I don’t need stuff that I’m going to waste countless hours trying to get working that in the end I will have to pay someone else to figure out. For me PWM control=reliability, right? That’s what we are all shooting for OE reliability but if it’s comolicated and we can’t get it to function properly than it defeats the whole purpose. KEEP IT SIMPLE STUPID that’s my motto. If something offers PWM reliability and plug and play GO FOR IT!






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