Auto. No Drive. Reverse works. Help!

[MrNeedles]

Hey,
Today, a buddy and I went on a tuning run around town. When we got back to my house, we turned the car off for a bit. I had to move it further up my driveway, so I started her back up and put her in drive. There was a slight feeling on engagement but it just would not move. It inched a little bit at low rpm but not much.

Earlier in the day I put on a 24,000 gvw trans cooler because my previous one was leaking. Could low ATF cause this to happen? I haven't checked it yet becuause it was dark when we got back.

Reverse seems to work fine. The car idles and rev perfectly fine. The only thing I noticed was that it was slipping slightly at full throttle and shifting a bit odd but still running strong.

Building a race car just seems like for every one step forward, there's 2 steps back.

 

[1996dsm]

Yes, Low fluid could cause that.

I once bought a gst that didn't move except reverse, it was just low on atf fluid. Lol

 

[94allwheeldsm]

Check that fluid level and get back to us!

 

[2slow4now]

Yep fluid level first and check to make sure the oil isn't burnt or discolored as well. If the transmission oil pump is going bad it will cause the same symptoms.

 

[MrNeedles]

Well I just checked the fluid and it was low. I really hate reading these dipsticks but I'm sure I read it right. I ended up putting I'm roughly 3.5 quarts to get it to cover the dipstick.

I'm still having the same problem though. This trans was rebuilt 2 years ago with an IPT kit. It has only about 5,000 miles on it.

It just barely creeps in drive. Soon as I press the gas, rpms rise but I go nowhere. But the bov will sound as if there's load.

Any other suggestion guys?

Update:

Pulled out the tcu and the car seems to be driving better in limo mode. At least it moves when I press the gas.

So what does this mean? Malfunctioning TCU?

 

[MrNeedles]

Anybody have anymore input on this. I'm about to pull the trans. I found a member with a similar problem http://www.dsmtuners.com/forums/new...-has-reverse-but-not-drive-forward-gears.html . Hopefully it's just the converter.

 

[Phantom DSM]

Anybody have anymore input on this. I'm about to pull the trans. I found a member with a similar problem http://www.dsmtuners.com/forums/new...-has-reverse-but-not-drive-forward-gears.html . Hopefully it's just the converter.

You have mentioned in previous post that the car drove better when you disconnected the tcu, Have you been able to source another tcu to test with?
If not, here is a link on how to pull Tcu codes from your current one while connected.
TCU Codes

The tranny must be in neutral on level surface with motor running to check for proper fluid level. The fluid must be hot as well after a good drive(if possible at the moment) and cycled though all the gears and stopping at neutral. the fluid would be at the Hot mark. Not sure if you checked it that way.

 

[fierosail]

ok here is a little info
Transaxle Remains In 3rd Gear
* Defective contacts at ignition switch
* Defective Damper Clutch Control Solenoid Valve (DCCSV)
on valve body or wiring circuit
* Defective end clutch
* Defective front clutch retainer
* Defective front or rear clutch
* Defective kickdown band
* Defective kickdown servo switch
* Defective low-reverse brake
* Defective or improperly adjusted inhibitor switch
* Defective Pressure Control Solenoid Valve (PCSV) on valve
body or wiring circuit
* Defective pulse generators "A" and "B" or wiring circuit
* Defective Shift Control Solenoid Valve (SCSV) "A" or "B"
on valve body or wiring circuit
* Defective Transaxle Control Unit (TCU)
* Improper shift cable adjustment
* Low fluid level
* Low line pressure
* Malfunction in valve body
* "O" Ring for low-reverse brake circuit not installed
between valve body and transaxle case
------------------------------------------------------------------------------------------------------
Vehicle Will Not Move Forward
* Defective oil pump
* Defective one-way clutch
* Defective Pressure Control Solenoid Valve (PCSV) on valve
body or wiring circuit
* Defective rear clutch
* Defective torque converter
* Improper shift cable adjustment
* Low fluid level
* Low line pressure
* Malfunction in valve body
_______________________________________________________________
you got one of those 2 going on

this is how to test your Converter and see if it good

TESTING > TORQUE CONVERTER STALL SPEED TEST > STALL SPEED TEST PROCEDURE >

Watch tachometer. Ensure transaxle fluid level is correct. Start engine, and operate it until transaxle fluid is at normal operating temperature. Ensure engine operating temperature is approximately 180-190°F (80-90°C).
Block rear wheels. Apply parking and service brakes. Place transaxle in Drive, and open throttle to wide open position. Note maximum engine RPM. This is torque converter stall speed. Repeat procedure with transaxle in Reverse.
CAUTION: DO NOT open throttle to wide open position for more than 5 seconds, or transaxle damage may occur. If performing more than one torque converter stall speed test, operate engine at 1000 RPM in Neutral for at least 2 minutes to cool transaxle fluid before performing next stall speed test.
Stall speed should be within specification. Once stall speed is obtained, place transaxle in Neutral. Operate engine, allowing transaxle to cool. Stop engine and place transaxle in Park.
STALL SPEED SPECIFICATIONS
Stall Speed Engine RPM
3300-3800

next on list is to test the pump ( will need a oil presser tester)
TESTING > HYDRAULIC PRESSURE TEST >

Ensure transaxle is at normal operating temperature and fluid level is correct. Raise and support vehicle so drive wheels rotate freely. Install tachometer, and position it so driver can view it.
Note locations of hydraulic pressure taps on side of transaxle case and near oil pan. See Fig 2 . Remove plug, and install adapter and pressure gauge to each pressure tap.
CAUTION: A 400 psi (28 kg/cm squared) pressure gauge is required for checking certain pressures. See Fig 1 to determine when this gauge should be used in accordance with hydraulic pressure specification.
Measure hydraulic pressure at various specified engine RPM and transaxle gears. See Fig 1 . Ensure pressure is within specification. If proper line pressure or reducing pressure cannot be obtained, check for proper adjustment.
If proper pressure cannot be obtained, check for probable defective components. See Fig 3 . Remove pressure gauge. Install and tighten plug to specification.
Fig 1: Identifying Transaxle Hydraulic Pressure Taps
Fig 2: Testing Transaxle Hydraulic Pressures
save the last image to get a beter pic for some reson i cant get it clear
i hope this helps ill check back and see if you have any questions

 

[Phantom DSM]

Fierosail, is this info from factory service manual or other workshop info source ? This is very helpful, maybe we can get this to be a sticky. There is not too much diagnostic support for auto dsm's.

 

[fierosail]

Fierosail, is this info from factory service manual or other workshop info source ? This is very helpful, maybe we can get this to be a sticky. There is not too much diagnostic support for auto dsm's.

i use pro-demand for my shop and all-data and i know. in my rebuild trend ill cover allot of this for everybody. in my opinion if you can rebuild a engine you can rebuild a auto. they seem intimidation but they really not that bad till u get to the kind i posted a pic of .

 

[Phantom DSM]

We use mitchells, ill have to check into pro demand. Awesome info, much appreciated and helpful for original poster here. Ill be watching your thread as well.

 

[MrNeedles]

Ok. So it turned out that my TC was shot. Soooo... I'm swapping back to manual.

 

[EagleTalonTim]

MrNeedles, I will have to say that out of the past 13 years that I have owned DSM's, the Auto is by far the most reliable as long as you take care of it (Change fluid and don't brake boost every 5 minutes). I have destroyed over 8 manual transmissions in 6 years and finally got an Auto. So far, I have messed up 2 Auto transmissions in 7 years. The first one I snapped an axle and threw it into the case because one of the strut to hub bolts sheared off (Wrong size bolt), and the second one was because I had a coding error in my shift box as I was doing R&D which let me downshift at 4000 RPM into first gear. That was fixed and I am still using the same transmission.

With an Auto, you get more consistent times at the track, less drivetrain shock, less moving parts that can go wrong due to user error or abuse, and with the use of a shift box, you get to control the shifts like you can a manual....Minus the clutch of course