no low rpm power

[josephw]

hello, this is my first post here! just some info ony my truck...
01 1500 4x4 off-road, blacked out on 285/75's, grey leather interior, stock except for 3" single flowmaster 40- catback. hopefully many mods to come.
i have had this truck for about a year now and have a unique problem... looking at past posts i cant find one that is exactly like my problem. up to about 2000 rpm's i have NO power under moderate to full acceleration. it boggs down but it dont do any bucking, missing, backfiring, nothing like that. after 2000 rpm's it will jerk you back in your seat with the power surge. my transmission is acting up too, occasionally it kind of hops around between first and second until it gets up to about 35 or 40 mph, then it shifts fine, its only 1st and 2nd. most of the time it shifts perfect. also, the other day it wouldnt drop to 1st at a stop light until i shifted into first manually. ive heard this is a common problem but i havent heard a solution! the only code its showing is the low-speed output sensor which ive changed 3 times with no difference. i can clear the code, crank the truck, put it in drive, and it throws it right back up! i've done a complete tune-up about 5 months ago with no difference. sorry to ask so many questions right off the bat but i use this truck for my business and cant afford much down time. could this be the TPS, or is this all stemming from the trans? thanks in advance for any help. God bless!

 

[josephw]

i also replaced the catalytic converter with no improvement either

 

[SmokedRam]

Can you look on your PCM and see if it has a sticker that says "FACTORY AUTHORIZED UPDATE" on it?

 

[swamp_life hemi 05]

Replace the tps. That use to give me the same issues on an old Ford I had.

It aint easy.... bein' Easy

 

[josephw]

Can you look on your PCM and see if it has a sticker that says "FACTORY AUTHORIZED UPDATE" on it?

it doesnt have one but there is a clean place where it could have falle off from.

 

[SmokedRam]

Well, here's where I'd start just to rule everything out...

#1...get that trans problem fixed...your trans could be not shifting down to 1st and starting in 2nd which, would give you the symptoms you are having with your engine.

It's normally a bad solenoid in your trans that needs to be replaced.

 

[josephw]

I'm taking the truck in for trans service tommorrow but i'll put on a new TPS before i take it in, do you think the tp sensor has any effect on the trans issues?

 

[Okiespaniel]

Welcome to RF!

Your tranny is probably going to need a govenor pressure switch...or a PCM/ wiring issue which is causing your trans to start out in the wrong gear. I would also replace the OD/lockup selenoids while the valve body is out. If they haven't given you problems they will.
A fresh batch of fluid and properly adjusted bands should solve most everything else.

Your CEL is the VSS sensor on the output where a speedo gear would go right? Are you buying discount auto parts sensors?
If the tranny service doesn't solve the problem, check for pinched or damaged wires...and then get a sensor from Chrysler. Pay the 2.00


EDIT: BTW this isn't a guess deal on my part... I'm troubleshooting from a 2001 factory service manual. It shows either gps, PCM/wiring, or second gear lockup band is not engaging.

 

[SmokedRam]

It could...but, If you know for a fact that sometimes it's not shifting between 1st and second gears now, you need to drop the trans pan and valve body and replace the solenoids. You can get all fo them for about $120 or so from Transmissioncenter...or you can pay a shop to do them.

If it's starting in 2nd from a dead stop, it will have 0 power til the RPM's get up there to satisfy the gear...my old gen2 did the very same thing before I replaced the transmission.

 

[josephw]

Welcome to RF!

Your tranny is probably going to need a govenor pressure switch...or a PCM/ wiring issue which is causing your trans to start out in the wrong gear. I would also replace the OD/lockup selenoids while the valve body is out. If they haven't given you problems they will.
A fresh batch of fluid and properly adjusted bands should solve most everything else.

Your CEL is the VSS sensor on the output where a speedo gear would go right? Are you buying discount auto parts sensors?
If the tranny service doesn't solve the problem, check for pinched or damaged wires...and then get a sensor from Chrysler. Pay the 2.00

i'm buying borg-werner sensors from o'reilly's, its on the driver side of the tranny just above the crossmember, the scan tool says its the low-speed input sensor, i think i may have said output i my first post... sorry bout that

also, i can put the shifter in low myself and its still a lazy pig.

 

[Okiespaniel]

i'm buying borg-werner sensors from o'reilly's, its on the driver side of the tranny just above the crossmember, the scan tool says its the low-speed input sensor, i think i may have said output i my first post... sorry bout that

also, i can put the shifter in low myself and its still a lazy pig.

Borg Warner...that name, like so many others...used to mean something. Now it's just imported crap stuck in whatever box the distributor needs to put it in. I have had so many BW sensors fail a voltage test straight out of the box I don't even bother anymore.

Here's some service manula info:

SHIFTS DELAYED OR
ERRATIC (SHIFTS ALSO
HARSH AT TIMES)
1. Fluid Level Low/High.
1. Correct fluid level and check for leaks if
low.

2. Fluid Filter Clogged.
2. Replace filter. If filter and fluid contained
clutch material or metal particles, an
overhaul may be necessary. Perform lube
flow test.

3. Throttle Linkage Mis-adjusted.
3. Adjust linkage as described in service
section.

4. Throttle Linkage Binding.
4. Check cable for binding. Check for return
to closed throttle at transmission.

5. Gearshift Linkage/Cable
Mis-adjusted.
5. Adjust linkage/cable as described in
service section.

6. Clutch or Servo Failure.
6. Remove valve body and air test clutch,
and band servo operation. Disassemble
and repair transmission as needed.

7. Governor Circuit Electrical Fault.
7. Test using DRBT scan tool and repair as
required.

8. Front Band Mis-adjusted.
8. Adjust band.

9. Pump Suction Passage Leak.
9. Check for excessive foam on dipstick
after normal driving. Check for loose pump
bolts, defective gasket. Replace pump
assembly if needed.

I see you've mentioned the TPS...this can sometimes cause erratic shifting...usually whiles the truck is moving. Harsh downshifts in kickdown or aceelerating after turning a corner or tc lockup flutter at highway speeds are usually TPS issues. You can perform a voltage check to test one.

 

[josephw]

Borg Warner...that name, like so many others...used to mean something. Now it's just imported crap stuck in whatever box the distributor needs to put it in. I have had so many BW sensors fail a voltage test straight out of the box I don't even bother anymore.

i had no idea, i thought bw was a reputable brand. looks like im gonna have to befriend a dodge dealership counterman! i'm thinking that my front bands need adjusting and a good service will solve my issues. gotta get this fixed cuz i love this truck, id hate to have to shoot it!
(i only said that to use the shooter smiley hahaha)

 

[Okiespaniel]

BTW...what specifc code are you getting...I am looking at the service manual and is
P0720 the code your getting?

 

[josephw]

BTW...what specifc code are you getting...I am looking at the service manual and is
P0720 the code your getting?

yes i do believe it is P0720,

 

[Okiespaniel]

Yes...low speed sensor 15-60 mph...etc. The VSS is a big magnet that reads pulses off a rotating notched disc on the rear output shaft. There isn't much to fail inside it but on cheaper ones the windings apparently break down quicker...but you still should check for damaged wiring.
Dirt/metal buildup on the end that's in the tranny can also give a code. Since you didn't note that in your 1st post I though I'd mention it.