| Author |
Message |
augerdogger
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 6:56 pm: | |
I have a '94 Prevost with a DDEC II 8v92, ATEC 755, and a 3.21 rear end. Due to emissions and the rear axle ratio, I have very little low end from a dead start. I have heard that you can trick the DDEC controller into thinking that you have more turbo boost and it will inject more fuel. Does anybody know how and where to bypass the turbo boost sensor and the resistor value required to accomplish the DEED. Once it starts rolling and the boost comes up, it runs fine. |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 7:20 pm: | |
bound to be a chip for it..know they sell them for big trucks...hey jimmc9 |
Ed Jewett (Kristinsgrandpa)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 8:00 pm: | |
I read a post a while back that was about a similar problem and the guru (sorry I don't remember who) that answered, said that it was the DDEC that held the fuel back to keep the engine from smoking. Smog control I guess.
If you could find the sensor and put a switch on it, it might help but you would get a lot of smoke till the rpms increased.
Have you ever thought about a propane injection system? Some of the truckers (short haul) around here have them.
Ed |
pete32174
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 9:04 pm: | |
TURBO BOOST SENSOR (TBS) is a three wire device
TBS connector #12015384 terminals are marked
A - B - C on outside of connector
terminal A = engine sensor return (-)
Terminal B = signal
Treminal C = engine harness 5 volts (+)
step 1
measure OHMs between term A and C (record OHMS)
(this should be greater than 10,000 ohms)
Step 2
measure OHMS between term A and B
(this should be less than 5 ohms) - (no boost)
step 3
to determine resistance at full boost
1-attach volt meter between term B(+) and A(-)
2-run bus at max or hign boost - record volts
step 4
The resistance at max or high boost equals
Voltage reading at full/max boost (in step 3)
divided by 5 volt (reference voltage)
times the Ohms from (step 1)
I can fax you a copy of the DDECII Page for TBS
Pete RTS/Daytona
.____________
/_][][]/____/[]_| 1989 RTS-II T70206 6V92-TA DDEC-II V731 4.10/24.5
*--O-----------O-* Daytona FL.-Hard Beaches/Soft Women (386)672-0571 |
Pete RTS/Daytona
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 9:11 pm: | |
this is not a bus 8v92 - but it will show you what a TBS looks like
http://www.tpub.com/content/constructionpaletizedsystems/TM-9-2320-364-20-4/css/TM-9-2320- 364-20-4_711.htm |
Greg Roberts (Gregeagle20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 04, 2004 - 10:07 pm: | |
As I have mentioned in the past, the answer is too hook up a prolink to the computer and and turn off the smoke control. I did this with my 6V92 DDEC II and it made a HUGE difference. Detroit can also do this with a laptop and they can do it with a prolink too. |
augerdogger
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 05, 2004 - 12:47 pm: | |
Thx for the input.
Greg: I like your approach but I don't own a prolink and my local DD service won't touch it because it is emission related.
Off the record, it was recommended to pull B to ground through a resistor value of about half the value measured using Pete's approach. Pete how do I get high boost w/o moving? Can I use the output from my air compressor set to say 30 psig?
bill |
Henry R. Bergman, Jr. (Henryofcj)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 05, 2004 - 4:53 pm: | |
My brother's fire department shops did something to the computer(s) on their older apparatus powered by 6V92TI and 8V92TI computer controlled Detroits.
Do NOT know what they did, but turned real slugs into rubber burners. Just a reprogramming thing. Tremendous difference, according to my brother.
No other apparent changes. Seems the computer would not let the apparatus employ immediate full power. Anyway, they fixed the problems. Legal? Do do know. Good luck. |
Pete RTS/Daytona
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 05, 2004 - 5:22 pm: | |
Augerdogger
Hmmm let's see now
Radio Shack part # 271-1715 10k linear taper potentiometer
just wire it in place of the sensor - with the wiper terminal to "B" and the other terminals (10K) to "A" and "C"
dial the pot to half way (5K) - look for black smoke (should be running rich) - see what the acceleration is like - don't rev real high cause you would be running lean at max boost conditions cause your "hard wired for 5k
try a couple of pot settings - If the acceleration is good - then use a switch to "cut in" the pot when you need takeoff power
or
I'm Not sure what boost pressure a D/D can make at full boost - but if someone else that has a guage can tell you - then you could also remove the sensor and duplicate the pressure input with your shop compressor and do all the actual measurements "on the bench"
Pete RTS/Daytona Senior Engineer - IBM 30 years retired |