Poor Acceleration from a stop / DDEC I II III IV / smoke control / Fix ??

[RTS/Daytona]

Hi - Good News for DDEC (I-II-II-IV) Owners with poor acceleration from a stop

In talking about 6V92TA's with a painfully slow response when starting from a dead stop only - seems their DDEC is set with
some kind of  "smoke control" option - they do not smoke when you mash the throttle down 

DDEC I -
Thanks to the work of Butch Williams - Luke at US Coach stocks an EPROM replacement for approx $100 that will cure most N.J. MCI DDEC I of their poor acceleration. DDEC I's  have a replaceable EPROMS and are not programable

DDEC II,  DDEC III, DDEC IV,
Bill Gerrie and I have worked on this problem for the last few days- Via long distance phone call Between Daytona and Toronto - Thank
goodness for "Unlimit USA/Canada phone plans)

Bill used his PROLINK to verify and test the settings and ideas -

First a little history
The D/D DDEC TURBO BOOT SENSOR
old part#--- 16070629
new part#- 23528418
is a 3 pin solid state IC device
pin A = Sensor Return
pin B = Signal Line
pin C = +5 volt supply line

pin B - operating range - approx .5v to 4.75 - voltages outside this range will cause a DDEC Fault
example
pin B @ 1.00 volts = approx 00 PSI Boost
pin B @ 2.25 volts = approx 10 PSI Boost
pin B @ 3.80 vollts = approx 20 PSI Boost

<>The PROLINK was used to verify the correct action of Bill's TBS without the modifications

<>Bill came up with a unique solution - A 100 ohm resistor between pin B (sense line) and C (+5 volts) - will pull up the voltage at the sense line (pin B) to what would be an approx 4-5 psi boost voltage level (as measured/verified with the PROLINK)

<>AS the actual boost pressure increases past 5 or 6 PSI the pull-up effect goes away - allowing normal TBS voltage levels

<>AT full boost the pull-up resistor has no effect

<>The net result is that the DDEC thinks that there's is a little  boost pressure available at IDLE and allows for more fuel to be
delivered to the injectors upon acceleration

<>This does mean that if you mash the pedal - you will produce some black smoke - adding a 100 ohm potentiometer to the existing
100 ohm resistor will help you dial out excessive smoke - or - just use the throttle pedal wisely (especially in front of the smog control guys)

<>Idle still remained smoke free

Pete RTS/Daytona

[RTS/Daytona]

Your Result may vary - Use at your own Risk

[Clarke Echols]

DDEC II,  DDEC III, DDEC IV,

First a little history
The D/D DDEC TURBO BOOT SENSOR
old part#--- 16070629
new part#- 23528418
is a 3 pin solid state IC device
pin A = Sensor Return
pin B = Signal Line
pin C = +5 volt supply line

pin B - operating range - approx .5v to 4.75 - voltages outside this range will cause a DDEC Fault
example
pin B @ 1.00 volts = approx 00 PSI Boost
pin B @ 2.25 volts = approx 10 PSI Boost
pin B @ 3.80 vollts = approx 20 PSI Boost

<>The PROLINK was used to verify the correct action of Bill's TBS without the modifications

<>Bill came up with a unique solution - A 100 ohm resistor between pin B (sense line) and C (+5 volts) - will pull up the voltage at the sense line (pin B) to what would be an approx 4-5 psi boost voltage level (as measured/verified with the PROLINK)

<>AS the actual boost pressure increases past 5 or 6 PSI the pull-up effect goes away - allowing normal TBS voltage levels

<>AT full boost the pull-up resistor has no effect

<>The net result is that the DDEC thinks that there's is a little  boost pressure available at IDLE and allows for more fuel to be
delivered to the injectors upon acceleration

The DDEC guy at the DD truck shop at Stewart &Stevenson in Denver told me to put the 100 ohm resistor in series with the center wire from the boost sensor.  To prevent problems at smog test, add a SPST switch in parallel with the resistor and close it when testing.  I haven't tried it on my S-50 DDEC II engine yet.  That engine is amazingly clean at smog test (275-HP version).

Clarke

[RTS/Daytona]

Clarke

Bill tried putting the 100 ohm resistor in the center wire - (pin B) - it did nothing at all
It didn't change the signal or register anything higher on the PROLINK

I had seen this post before about the 100 ohm in the center wire - that's one of the things that got us started testing
and it was one of the very first things we did - trust me - it didn't work

I had also heard about switching the A and B wire to fool the computer - that didn't work either

Flipping the A and C wire made it work backwards - full boost at idle - none at full speed/load

Pete RTS/Daytona

[homermandy]

I have a nice clean 100ohm resistor to install tonight Will let you know how it goes. Thanks

[homermandy]

Ok, I must report. I have a roadburner. I installed the 100ohm resistor between the 5V line and the middle line of the turbos boost sensor plug. OMG, forgot i was in a bus. It really does make a huge difference. I had to be careful and not mash the accelerator(too much black smoke), but if you take care not to mash from a stop, the response is 100 times better than without the resistor. I cut some sheathing off the wires and twisted the resistor around each wire, then squeezed with pliers and put tight electricians tape over it.  I should solder it, but the resistor ends are long enough to wrap 3 or 4 times easily, so the connection should be fine. I suggest others try it, thanks for the tip!!!!!!!!!!!!!!!!!!!!111

[RTS/Daytona]

Homermandy

Could you do us a big favor - Could you try a 200 ohm resistor and tell us about the acceleration / smoke

Pete

HEY BILL GERRIE - YOUR THE MAN !!!!!

[RTS/Daytona]

homermandy

Please remember - BLACK SMOKE = OVER FUELING - That can wash down cylinders - Please be carefull !!

let's us know how more resistance works for you - Please

Pete RTS/Daytona

[homermandy]

I'll try to pick some more resistors up tomorrow. Might not be until Friday. I think the 100ohm is fine as long as you dont mash the pedal:))) Will keep you posted. Thanks

[homermandy]

I picked up a potentiometer and some additional 150 and 220 ohm resistors yesterday. I'll try some additional testing this week. Per Greg Peterson, I am also wondering what the additional amperage is doing to the circuit. Has anyone run this way for an extended period of time? It would be nice to know someone has 200K miles on this mod and no problems:-)

[DrivingMissLazy]

Adding resistance to a circuit would decrease the amperage.
Richard

I picked up a potentiometer and some additional 150 and 220 ohm resistors yesterday. I'll try some additional testing this week. Per Greg Peterson, I am also wondering what the additional amperage is doing to the circuit. Has anyone run this way for an extended period of time? It would be nice to know someone has 200K miles on this mod and no problems:-)

[RTS/Daytona]

Rich

Actually the added resistor is in sort of a parrallel configuration - at worst case it could add 50 milliamp additional load to the 5v sensor supply line - thats 1/20 of an amp

you guys decide for ourselves -

Pete RTS/Daytona

[DrivingMissLazy]

Sorry, I thought it was in series.

I believe you stated that this circuit is bypassed when the normal circuit takes over. Is that correct? If so, then the currrent would not be any more than the normal circuit draws.
Richard

Rich

Actually the added resistor is in sort of a parrallel configuration - at worst case it could add 50 milliamp additional load to the 5v sensor supply line - thats 1/20 of an amp

you guys decide for ourselves -

Pete RTS/Daytona

[RTS/Daytona]

DML

The Turbo Boost Sensor is an unique IC Device (not just a simple variable resistor - I do not know it's actual internal configuration - the 100 ohm resistor appears to hold the bias at a level that approximates a few pounds of boost and seems to have no effect after the actual boost pressure climbs above that valve.

see--> http://www.autoshop101.com/forms/h35.pdf  - look at page 4 & 5   -   

Pete RTS/Daytona

[homermandy]

Update:
I installed a 220ohm resistor in place of the 100 ohm and the slow acceleration was back.  Now I did get my Pro-Link last week and while idling with the 100ohm resistor, I did not register any boost on the Pro-Link.  Anyways, I installed the 100 ohm resistor back in place and road-burner is back.