Zener Diode Boost Fooler
Thread Starter
|
Senior User
Joined: Mar 2007
Posts: 473
Likes: 3
From: Issaquah, WA
Zener Diode Boost Fooler
Anybody out there using a zener diode at the MAP sensor to limit the boost signal to the PCM in order to avoid defueling.
Just curious if there is a downside to this method..?
Mike
Just curious if there is a downside to this method..?
Mike
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
Popular opinion says it works. There are a few guys who caution against it for reasons I can't remember, but it had to do with damage to the MAP sensor. I have one some place... I wish I could find the bugger and install it.
I had a thread on this a while back, I'll try to dig it up.
I had a thread on this a while back, I'll try to dig it up.
Hotshot
Joined: Jan 2008
Posts: 13,144
Likes: 11
From: Rochdale MA
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
I think the closest zener is going to be 4.7 volt.
Not sure what the output impeadence/drive capability of the MAP sensor is but there may be an issue with the zener clamp current, depending on what diode you use. I believe the EEC-IV inputs are BJTs with input impeadence in the 10's of kohm range so it will only ask the sensor for 1ma or so. most zeners need way more current than that to hold there voltage rating (4.7volts or whatever)
I went with the ITP OBA because it is proven, simple and I didn't want to hack up the factory wiring.
Now, if you really wanted to over engineer a voltage clamp with nano second delay, use a mircrocontroller with a A/D & D/A converters and write some software
Not sure what the output impeadence/drive capability of the MAP sensor is but there may be an issue with the zener clamp current, depending on what diode you use. I believe the EEC-IV inputs are BJTs with input impeadence in the 10's of kohm range so it will only ask the sensor for 1ma or so. most zeners need way more current than that to hold there voltage rating (4.7volts or whatever)
I went with the ITP OBA because it is proven, simple and I didn't want to hack up the factory wiring.
Now, if you really wanted to over engineer a voltage clamp with nano second delay, use a mircrocontroller with a A/D & D/A converters and write some software
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
I think the closest zener is going to be 4.7 volt.
Not sure what the output impeadence/drive capability of the MAP sensor is but there may be an issue with the zener clamp current, depending on what diode you use. I believe the EEC-IV inputs are BJTs with input impeadence in the 10's of kohm range so it will only ask the sensor for 1ma or so.
I went with the ITP OBA because it is proven, simple and I didn't want to hack up the factory wiring.
Now, if you really wanted to over engineer a voltage clamp with nano second delay, use a mircrocontroller with a A/D input and write some software
Not sure what the output impeadence/drive capability of the MAP sensor is but there may be an issue with the zener clamp current, depending on what diode you use. I believe the EEC-IV inputs are BJTs with input impeadence in the 10's of kohm range so it will only ask the sensor for 1ma or so.
I went with the ITP OBA because it is proven, simple and I didn't want to hack up the factory wiring.
Now, if you really wanted to over engineer a voltage clamp with nano second delay, use a mircrocontroller with a A/D input and write some software
You lost me after EEC-IV
Trending Topics
Thread Starter
|
Senior User
Joined: Mar 2007
Posts: 473
Likes: 3
From: Issaquah, WA
Chase, Thanks for the links. Not sure I'm seeing a definitive answer. Maybe effects the map, maybe not... Maybe need a to add a resistor, maybe not... Both the diode and a mechanical solutions have some "non-ideal" characteristics.
Being a mechanical guy who doesn't tust anything electrical, I guess I'm leaning toward the mechanical solution.
Thanks again.
Being a mechanical guy who doesn't tust anything electrical, I guess I'm leaning toward the mechanical solution.
Thanks again.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
Post Fiend
Joined: Jun 2006
Posts: 9,714
Likes: 2
From: White Mnt's,New Hampshire
electronic "do-dads". a number of these were replaced due to their effect on low speed, low boost drivability. don't mess with the electronics, the PCM and MAP Sensor maintain 100% normal connectivity with no electronic interference withthe OBA..the OBA lets the map see live ###''s at that moment.. the resistor is slow to re act..
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
electronic "do-dads". a number of these were replaced due to their effect on low speed, low boost drivability. don't mess with the electronics, the PCM and MAP Sensor maintain 100% normal connectivity with no electronic interference withthe OBA..the OBA lets the map see live ###''s at that moment.. the resistor is slow to re act..
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
all electronics operate at the speed of light.
it is the non-ideal charateristics of a diode that give the precepion of a 'delay'. the plot by ernest eugene in one of the links above shows it well
adding a resistor in series to the diode circuit to protect overloading the MAP will only make it preform less ideal, or not at all. a typical zener needs to be reverse biased and fed 20-100ma to get it to drop (or hold) it's rated voltage. the MAP isn't going to support that, it would need a voltage follower current amplifer.
it is the non-ideal charateristics of a diode that give the precepion of a 'delay'. the plot by ernest eugene in one of the links above shows it well
adding a resistor in series to the diode circuit to protect overloading the MAP will only make it preform less ideal, or not at all. a typical zener needs to be reverse biased and fed 20-100ma to get it to drop (or hold) it's rated voltage. the MAP isn't going to support that, it would need a voltage follower current amplifer.
Thread
Thread Starter
Forum
Replies
Last Post
Scndsin
1987 - 1996 F150 & Larger F-Series Trucks
19
Feb 6, 2019 11:48 AM
rtcabal
1967 - 1972 F-100 & Larger F-Series Trucks
16
Dec 29, 2015 07:04 PM
