hello all,

im new to the site and new to the Cummins - -i recently bought a 94 3500 4x4 with 124k on it - the tranny was supposedly rebuilt about 20k ago.

i love the truck but the trans makes nervous, it shifts fine through 1-2-3 then it does some weird stuff between 40 and 60 mph, goes into over drive then jumps back out sometimes, goes into overdrive then seems to go into a torque converter lock up{?} - -the rpms drop to around 1600-1800 rpm at 60 mph.................but it jumps out like every 30 seconds sending the rpms to 2000-2100 - - -back and forth - - -driveing me crazy..........

if i take it out of overdrive it runs 2500-2600 rpm at 55-60 mph which feels like its going to pop out of the hood and slap me in the face

whats the deal? is it just the nature of the beast? ive heard nightmare stories about early Dodge Cummins transmission combinations - - -

this is a plow truck and a trailer puller so i need to be confident in my rig.

any help or advice on were to start and what to do or look for is greatly appreciated

thank-you

when i wired my pyro guage i just grabbed a hot wire under the dash (not the smartest idea) drove my truck for about 35 miles on the freeway and it was doing the same things as you have described. so i pulled over and unhooked the guage and it was fine. never found out what wire i grabbed but would asume it was to do with the tranny. that is just my story as i don't know enough about trannys and the electrical supply to fully understand. have never had that problem since.

lodal cummins's Sig:

1996 Dodge 12 Valve
100 Fuel Plate ff, Silencer Ring Removed, K&N Filter, AFC Tuned, Boost Elbow
3" exhaust with aereo turbine muffler
Boost & Pyro Meter Gauges, Automatic with low stall converter & Shift Kit kdp killed, timing 15.5* 3kGSK

Sounds like the TPS or the brake light switch. Both can cause lock-up issues are are pretty common.

Dusterb318's Sig:

-Phil-98 Dodge Ram 2500 4x4,12V,47RE Suncoast Billet input shaft, Suncoast H/D Extreme Trans kit, Goerend Triple disc converter, FASS 150/90, FASS Suction tube, Amsoil Ea air and pre-filter, 100 plate, 4K GSK, 370's, AFC Mods, CoolerTubz intake, 5" stacks, BD-SBS, Autometer Z-series Pyro/Boost/Trans/FP, Amsoil front to back.
'73 Plymouth Duster -318/904- 11.85@117

ok forgive my ignorance, im a reasonably adept mechanic and can do most anything...................but.................... ....

what's a tps?

i do have a touchy brake light switch, i noticed one day working under the dash that my brake controller was "on" so i finally found that just pulling up on the pedal a little bit turned it - - - think there might be a wireing short or something causeing and issue with the transmission???

what would i look for ?

while we're talking about my ignorance on cummins motors, , i was told this truck has a bigger turbo and a "cam" in the injector pump? - - the turbo says "swittzer" on it and the injector pump looks pretty original - -is there something i can check with out takeing the pump apart to verify this information?

ive put a K&N cold air intake on her, and it has 4 inch exhaust on it right now, my buddy is building me a 4x8 inch rectangle stack here in a week or so, i have a hal-pak box between the cab and flat bed and the pipe will run up the center between the bed and box with a big nasty flapper on top of course.........

thanks for the help !!! looking forward to more...


"help Boss make a monster"

TPS switch = Throttle Position sensor

TPS testing and adjustment

ill be checking this as soon as i have an opportunity - - -thankgiving coming up ya know- -momma won't like me under the hood while families in the house,

thank you for the tip

Al

boss3500's Sig:

SnowBoss
__________________________________________________
1994 Dodge 3500 4x4, 12V, Ford captains chairs and center console interior, K&N intake, Schwitzer turbo, 5 inch single stack[no muffler], flat bed, hal-pak box, lots-o lights, Boss 9'2" VXT plow, swenson spreader

I doubt they changed the cam in the pump. More than likely it has a different fuel plate in it maybe they called it a cam plate......you definetly have a different turbo as they can stock with Holset turbos.

ok thanks..............being an old powerstroke fan, i have 2 tuners sitting on the shelf now that are useless to me, and the 12v being a mechanical motor i have no idea what can be modded and still keep it dependable. I am not going to be pullin sleds or doing monster mudding with this rig but would love to get as much power and attitude out of her as posable without blowing stuff up................whats the most common things done to these beasts to tweak em up a bit?

thanks for all the help, this is a good site. ive been to a couple other forums and the people acted like i was bothering them because i wasn't driving a 60,000 dollar 4 door dually haulin cattle

Al

get gauges(boost,pyro,trans temp)<-- first thing!!! tourqe converter, valve body, pull the plate,slide the afc and crank it open, set timing to 18.5* out, head studs, and a boost elbow.should be a good start for ya

12.valve.hauler's Sig:

97 ctd 4x4,230,000,215hp pump,no plate, star wheel ff, silencer ring disposed of, open turbo,courser mt's, 5 inch mitre cut stack(stuck up under the bed)

ok gauges are pretty self explanitory - - and i think i need a tourqe converter now, so whats a decent brand and how much can i wxpect to pay for one?

the fuelplate and timeing stuff sounds pretty intense...........are these hard things to do?

head studs im assuming are for added strength from over fueling?

and whats a boost elbow and what does it do


thanks for the help

the fuel plate is pretty easy, you can get a new one or grind your own. you could even just slide yours if your looking for a small gain. i would recomend going with no plate but make sure you have torque converter and valvebody to hold it. the timing is best done by someone who knows what they are doing, but if you are a pretty decent mechanic its not that hard. a boost elbow is used to fool the wastegate to get more boost out of you turbo. its a basic install and the you just play around with it till you get where you want it. if you ask some of the other guys they can give you step by step instructions wit pics. the guys on this site will take care of ya

sweet...........

can i assume messing with the fuelplate, either modding it or removeing it will affect mileage? or does it just use the fuel to its full capabilities?

ill look into the boost elbow for sure - - i think i saw a pic on the site of one, is it on the right side of the motor going over the injector pump?

it sounds like gauges are definatley in order but more importantly getting this tranny solid - - - i dont want to put stock parts back into the truck if i don't have to and im haveing a hard time finding a good tranny or converter and what i have found are thousands of dollars.
if im gonna have to spend that kind of money can i put a 6 speed manual in her or better yet find an Allison trans somewhere? theres got to be a better option than a beefed up 1960's tourque flight ..............no?

yea there is always the option of a manual tranny, i would say go for it. good clutch and tranny and youll never have to worry about it again. now as for the fuel plate it depends on how you do it. as long as you keep enough air to lean it out youll get great milage but if you jus blow a bunch of smoke it wont help milage. and the reason we say gauges first is because if you dont know how the motor is reacting to all the mods its real easy to mess up something. with my truck im running a stock turbo with no plate and i used the afc to tune it out and i was getting pretty damn good milage, much better than stock, and a whole lot more power. let me warn you though, once you start modding youll catch the bug and enough is never enough.

(once you start modding youll catch the bug and enough is never enough.)

Soooo true

97cummins's Sig:

oh im very well aware of the moding bug..............its a love hate relationship for sure. i come from a very bad sports car habit 80's and early 90's liquid cooled Porsche's are my weekness................a very nasty divorce cured me of that though....

so now im fat and happy with my high school sweetheart and any moding i do has to be functional {never could get a 928S4 to push much snow} but i can totally see the need for 6 or 700 horses to get the lawn mower hauled down the road bwah hahahahahaha hence my concern for this tranny,

jeesh if im reading right info from the forums and websites im looking at 4-5000 bucks to do a built up billet shaft trans and a good triple disk TC ? does that sound about right? thats what i paid for the truck ...........dam and thats before i touch the pump or turbo

i built a full autocross 944 SM2 for 4500.....................