Tranny help?

[reborn55]

Coming back from Bunny run yesterday--thought I felt the trans slipping a little in first gear only from a dead stop.  Not every time--but still worrysome.  Other gears, downshifting hard acceleration etc. are all OK after shifting out of first.  It has the 96-97 Vortec 5.7 with 4L60E out of a truck in it with Street and Performance wiring harness.  Kinda looking for some diagnostic aids before I condemn the trans.  Fluid is clean and no burning odor.  Level seems high--dip stick tube is not in factory position(PO install).  Little hard to get in the last inch to lock in position.  Going to pull pan later this week and see if any codes appear.

Did notice that when idling in drive the speedometer registers about 20 mph and is registering miles at the same time.  Could this be sending the computer goofy signals which in turn is sending the trans erroneous signals and possibly causing the slippage.

Thanks for any help.

[Crosley.In.AZ]

Coming back from Bunny run yesterday--thought I felt the trans slipping a little in first gear only from a dead stop.  Not every time--but still worrysome.  Other gears, downshifting hard acceleration etc. are all OK after shifting out of first.  It has the 96-97 Vortec 5.7 with 4L60E out of a truck in it with Street and Performance wiring harness.  Kinda looking for some diagnostic aids before I condemn the trans.  Fluid is clean and no burning odor.  Level seems high--dip stick tube is not in factory position(PO install).  Little hard to get in the last inch to lock in position.  Going to pull pan later this week and see if any codes appear.

Did notice that when idling in drive the speedometer registers about 20 mph and is registering miles at the same time.  Could this be sending the computer goofy signals which in turn is sending the trans erroneous signals and possibly causing the slippage.

Thanks for any help.

the speed-O reading at a stop is curious.

Should that cause slippage?  Nope.... the trans has minimum pressure at stop while in gear. IF all is OK , the trans should not slip or drop out of gear.

I am curious of the symptoms that lead to your slippage theory.....  :?

Does the engine rev up?  Is there a 'thump , bump feel" as you accelerate from a stop?

Are you using the GM PCM to control engine and trans with the mentioned wire harness??

[reborn55]

Coming back from Bunny run yesterday--thought I felt the trans slipping a little in first gear only from a dead stop.  Not every time--but still worrysome.  Other gears, downshifting hard acceleration etc. are all OK after shifting out of first.  It has the 96-97 Vortec 5.7 with 4L60E out of a truck in it with Street and Performance wiring harness.  Kinda looking for some diagnostic aids before I condemn the trans.  Fluid is clean and no burning odor.  Level seems high--dip stick tube is not in factory position(PO install).  Little hard to get in the last inch to lock in position.  Going to pull pan later this week and see if any codes appear.

Did notice that when idling in drive the speedometer registers about 20 mph and is registering miles at the same time.  Could this be sending the computer goofy signals which in turn is sending the trans erroneous signals and possibly causing the slippage.

Thanks for any help.

the speed-O reading at a stop is curious.

Should that cause slippage?  Nope.... the trans has minimum pressure at stop while in gear. IF all is OK , the trans should not slip or drop out of gear.

I am curious of the symptoms that lead to your slippage theory.....  :?

Does the engine rev up?  Is there a 'thump , bump feel" as you accelerate from a stop?

Are you using the GM PCM to control engine and trans with the mentioned wire harness??

Thanks Tony.  

When I took off from a dead stop yesterday it would accelerate fine, then feel like the engine would rev a little--trans slip and then accelerate Ok--then shift into 2nd gear and on through the rest of the power band.    Shift into 2nd gear was a little sloppy.  Didn't happen every time but when it did it would pretty much act the same.  engage on initial acceleration , slip, then be OK.  Only time there was a problem was in first gear.

It is supposed to be the correct PCM--for the wiring harness.  Had no problem going to the show and since i had bought it--probably 400 miles and then on the way home it acted up.  

Guy at Stewart Warner said the speedometer is bad--don't know if I agree as it might be picking up a pulse near some of the wiring.  Was thinking about disabling it and see what happens.

Is there any thing I can do to check as to why it is slipping.  Would too much fluid cause this problem.  I know it can create problems.  

Thanks again

[Crosley.In.AZ]

2 things about the speed-O wire feeds.....

they must be twisted around each other . This cancels out 'ghost' signals from the wires.

2nd ; they should be wrapped in a foil to reduce RF interference .

IS the fluid level OK?

After market dip stick and tube   or is the OEM parts used??

[Dave]

Check the speedo leads and if its grounded at both ends with the braid or foil or what ever your cable has try disconnecting one end.. the grounds
Dave

[reborn55]

Thanks guys

Tony--fluid level according to the dipstick is overfilled.  It has the original dipstick in it but is mounted off to the side--in other words it is not bolted to the back of the motor, due to firewall clearance.  Will see if I have pic later this evening.  

Tony and Dave--not sure if the leads to trans for sensor are twisted or wrapped.  Previous owner installed the SW speedometer(dip switch calibration) and then added a Dakota Digital interface which I have used to try to calibrate the speedo.  Wires were wrapped together--pulled them apart last night will no apparent help.  Still sat there in either Nuetral or Drive and registered 20 mph and clicked off mileage on the odometer.

Also no codes stored.

Thanks for the help.

[Dave]

Thanks guys

Tony--fluid level according to the dipstick is overfilled.  It has the original dipstick in it but is mounted off to the side--in other words it is not bolted to the back of the motor, due to firewall clearance.  Will see if I have pic later this evening.  

Tony and Dave--not sure if the leads to trans for sensor are twisted or wrapped.  Previous owner installed the SW speedometer(dip switch calibration) and then added a Dakota Digital interface which I have used to try to calibrate the speedo.  Wires were wrapped together--pulled them apart last night will no apparent help.  Still sat there in either Nuetral or Drive and registered 20 mph and clicked off mileage on the odometer.

Also no codes stored.

Thanks for the help.

Thats crazy.. Heres the deal even a pulse sender can cause rfi radio frequency interference and can also be messed up by it. When you only ground one end like at the sender and dont ground it at the other the RFI can kinda escape with out getting into the instruments. For lack of a better way to describe it I hope this helps.
Dave

[reborn55]

Thanks guys

Tony--fluid level according to the dipstick is overfilled.  It has the original dipstick in it but is mounted off to the side--in other words it is not bolted to the back of the motor, due to firewall clearance.  Will see if I have pic later this evening.  

Tony and Dave--not sure if the leads to trans for sensor are twisted or wrapped.  Previous owner installed the SW speedometer(dip switch calibration) and then added a Dakota Digital interface which I have used to try to calibrate the speedo.  Wires were wrapped together--pulled them apart last night will no apparent help.  Still sat there in either Nuetral or Drive and registered 20 mph and clicked off mileage on the odometer.

Also no codes stored.

Thanks for the help.

Thats crazy.. Heres the deal even a pulse sender can cause rfi radio frequency interference and can also be messed up by it. When you only ground one end like at the sender and dont ground it at the other the RFI can kinda escape with out getting into the instruments. For lack of a better way to describe it I hope this helps.
Dave

Thanks again.

Dave, the interface is grounded at the dash.  There are four wires in and out--looks like about 18 gauge with one grounded.  Wasn't able to crawl under the car this evening, but according to wiring schematics from Street and Performance the wire to the speed sensor look to be twisted like you guys have said.  So I am going to guess that the wire harness is correct and that the problem is with the speedometer and or interface.  Think I might just go ahead and buy a new set of TPI gauges andtry them.  Might be better off in the long run by geting away from the dip switches.
What kind of problem would I run into if I disable the speedo.  Had another friend die suddenly yesterday and need to use the car for services.  

Tony am enclosing a picture of the dipstick tube install on my setup

Thanks again for all your help