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Author Topic: Poor Acceleration from a stop / DDEC I II III IV / smoke control / Fix ??  (Read 4825 times)
RTS/Daytona
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« on: July 03, 2006, 04:46:13 PM »

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
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RTS/Daytona
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #1 on: July 03, 2006, 07:45:39 PM »

Your Result may vary - Use at your own Risk
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Clarke Echols
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« Reply #2 on: July 04, 2006, 12:46:31 AM »


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
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RTS/Daytona
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #3 on: July 04, 2006, 10:59:17 AM »

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
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homermandy
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« Reply #4 on: July 05, 2006, 01:42:31 PM »

I have a nice clean 100ohm resistor to install tonight Smiley Will let you know how it goes. Thanks
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1991 Eagle 15
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« Reply #5 on: July 05, 2006, 03:24:35 PM »

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
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RTS/Daytona
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« Reply #6 on: July 05, 2006, 04:49:21 PM »

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 !!!!!
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« Reply #7 on: July 05, 2006, 04:55:18 PM »

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
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« Reply #8 on: July 05, 2006, 05:45:44 PM »

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
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1991 Eagle 15
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« Reply #9 on: July 10, 2006, 06:26:52 AM »

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:-)
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« Reply #10 on: July 10, 2006, 08:05:04 AM »

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:-)
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #11 on: July 10, 2006, 09:11:43 AM »

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
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« Reply #12 on: July 10, 2006, 10:12:31 AM »

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
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #13 on: July 10, 2006, 12:10:31 PM »

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
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« Reply #14 on: July 24, 2006, 05:28:18 AM »

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.  Smiley
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1991 Eagle 15
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« Reply #15 on: July 24, 2006, 05:30:01 AM »

Forgot to mention that on my Pro-Link, there is an option which shows Smoke Control YES/NO(I think option 31). Anyways, it shows NO on the ProLink.  I would have thought it would be set to Yes. 
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1991 Eagle 15
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #16 on: July 24, 2006, 06:06:20 AM »

homermandy

Thanks for the followup - hmmm don't understand your PRO-LINK "no boost" reading with the 100 ohm - when Bill did the testing his Pro-Link showed a few pounds boost ??

Glad the 100 ohm still works for you - received another report yesterday - 100 ohm worked great for a Blitz re-built RTS ddec II 6V92TA

Pete

I don't understand D/D "smoke Control" option - I'm confused - but we appear to have a good "work around" - the 100 Ohm resistor wired between the Turbo Sensor pin "C" and "B"
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« Reply #17 on: July 24, 2006, 04:25:21 PM »

Took another spin tonight. Had the prolink hooked up to monitor boost while driving.  Interesting, the boost registered on the prolink was half of the boost registered on my guage.  I can pull about 20psi at full boost.  However the prolink never got over about half.  Now someone else had a similar(maybe not similar) issue where the ECM read full boost then fell to zero. His problem was fuel starvation if I remember correctly. Anyways, it makes me intrigued.  I didn't measure boost without the resistor yet, but I would believe it would have no effect in the upper boost range. Anyone else seen this?  I doubt my guage is wrong......
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1991 Eagle 15
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« Reply #18 on: July 24, 2006, 05:18:04 PM »

I suppose on the troubleshooting side, 1st I should make sure I have 1volt at pinB for zero boost.  If that does not register correct voltage, sensor may be broken. AND, it could be possible I have a small enough leak in the hose from the blower to the sensor causing the low voltage. But I would think if voltage measures around 1V at idle, sensor probably is ok. 
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1991 Eagle 15
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #19 on: July 24, 2006, 05:20:30 PM »

homermandy

Hmmm - I think you need to remove the resistor and hookup the prolink and take it for another ride - just to eliminate any false readings due to the resistor

But I don't believe that the resistor has any effect at full boost

Pete RTS/Daytona
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« Reply #20 on: July 24, 2006, 05:52:31 PM »

Ok, so I got more ambitious. Without the resistor, lead c measures 5V, lead B measures 1V.  Prolink registers 0psi.
With the resistor, 5V at C, almost 2V at B, and still 0psi at Prolink. Won't be able to take for a spin until tomorrow evening.
Also put 5V directly to B and a fault registered on Prolink. hmmmmm
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« Reply #21 on: July 24, 2006, 06:50:03 PM »

pin B - operating range - approx .5v to 4.75 - voltages outside this range will cause a DDEC Fault
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« Reply #22 on: July 25, 2006, 04:12:37 PM »

Ok, so I think we may not understand how the DDEC program works. I had a potentiometer wired for about 50ohms between b and c pins. Checked voltage was about 3 volts or so. When yu turn on the ignition, it takes a while for the prolink to initialize. But i quickly scrolled down to boost PSI and it was dropping to zero(soonest I could get the display scrolled it was about 5psi). So I believe the prolink is getting the correct psi reading, but I believe it uses other parameters also. Not sure why it would not stay on what would be like 10psi? But it definately dropped to zero.  hmmmm.
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« Reply #23 on: July 25, 2006, 06:29:15 PM »

Here is the link to the similar boost behavior....

http://www.busnut.com/bbs/messages/233/10261.html
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« Reply #24 on: July 26, 2006, 11:13:35 AM »

Neat stuff Pete.............Keep me posted.

Rich
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