TCCoA Forums banner

1 - 14 of 14 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1 (Edited)
This is an 03 4r70w in an 03 turbocharged 4.3l mustang. Full manual pa trans-brake valve body, Huge trans cooler, deep pan, etc...

The issue I am having is intermittent. On the manual upshift into 2nd gear the rpms drop off way to far and it looses power. With the current converter it should not drop below 5200rpm under wot. It is falling off to 4200 almost like the converter is locking up. All trans controls are on a toggle switch inside the cabin. The pass before this the car ran 6.78 @ 105 mph like a champ. Driving it home it performed flawlessly. Test pass on the street yesterday it smoked the tires on 1-2 upshift like it's suppost to. Anyone have insight or opinions as to where I should looking? How can you physically disable converter lock up? Would plugging the solenoid hole in the valve body do this? Could the lu solenoid be weak allowing fluid to engage converter lu?
 

Attachments

·
Super Moderator
Joined
·
10,768 Posts
It could have been the TC locking, but I bet it was the clutch slipping, starting at about the 47 second mark.

Datalog the output shaft, and you should be able to see if it was spinning.

I used to spin the 2-piece Driveshaft at about that RPM, lol.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
I added output shaft to my config file so next time I beat on it I'll have some data there. Any other pid recommendations to help diagnose this? I'm going to take a look at some old logs and compare the tc act slip to this log to see whatI can figure out also.
 

·
50 years of Mercury Cougar 1967/2017
Joined
·
1,265 Posts
Once the RPM's get to 5200 does it feel like the TC unlocked or like another gear or shift?
 

·
Registered
Joined
·
7 Posts
Discussion Starter #5
On the trans-brake 2 step at 3300rpm, launch and pulls fine through first, manually shift into 2nd and it feels like it was bogging down, feather throttle and upshift into 3rd and it was fine again. For what it's worth I have not tuned the car for the manual vb so the ecu still thinks it has the job of shifting/lu etc... Also this lu shift schedule on this tune has the converter locking bottom of 2nd gear like it came from the factory.
 

·
Registered
Joined
·
1,888 Posts
The converter locks in 2nd gear from the factory? Never noticed that before.

Al
 

·
50 years of Mercury Cougar 1967/2017
Joined
·
1,265 Posts
That's what's happening.

Some computers on quick RPM'ing engines have bizzare episodes.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #8
The converter locks in 2nd gear from the factory? Never noticed that before.

Al
On the 03 v6 mustang yes it does lock up under wot. Don't know why because this kills any performance thiscar has stock. Even blanket performance tunes like from bama, vmp, etc leave the converter locked as soon as it shifts into 2nd.
 

·
50 years of Mercury Cougar 1967/2017
Joined
·
1,265 Posts
After spending a few $ more than I liked, I had a stand alone transmission controller installed.
One of the most awesome devices made.

You could control up shift, TQ lockup and downshift.
All gears, shifts at any time.

I had an issue with over6000 rpm operation.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #10
After spending a few $ more than I liked, I had a stand alone transmission controller installed.
One of the most awesome devices made.

You could control up shift, TQ lockup and downshift.
All gears, shifts at any time.

I had an issue with over6000 rpm operation.
If I put the stock vb in my ecu would control it. Sucks that the only trans-brake vb is full manual because my car shifted awesome with the modified shift schedule.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #11
Bump, same issue still happening intermittent. I'm thinking the converter is still trying to lock on a full manual vb. I don't know how it would do this but is what I suspect. I run a 1.42 60' 6.50 @ 104mph no issue, next pass went 1.35 60' but 6.76 @ 102 and the issue appeared on this pass. Final pass run 1.29, 6.39 @ 108 mph no issues! Keep in mind tq lock-up is on a switch located inside the cabin as well as od. Rpm falls off to 4500rpm and it feels sluggish because rpm falls out of power range. Engine load is pegged at 2.0 when this occurs, imediatlly shift into 3rd and the issue is gone.

Is there a way to physically disable lock -up with out resorting to electronics? What if I pull the lu solenoid out and or plug the hole in the vb? I guess my question is how do you mechanically disable lu on this trans?
 

·
Registered
Joined
·
2,977 Posts
Look, there is NO way that the computer is locking up your converter if you have a MVB and are controlling OD and lockup with switches. You have severed the connection. Can't happen. I think those offering advice here have missed that you have a MVB with switches for control and that part has been taken totally away from the computer.

Unless the valve body came from Freddy Brown then I have had all sorts of goofy issues with them. Stuff like this from internal leaks was pretty common before I switched to his stuff and never looked back.

Not sure what it is, but if you have taken lockup and put it on an entirely separate circuit with switches where the computer can't touch it then it is for sure not the computer messing with lockup.

D
 

·
Registered
Joined
·
2,977 Posts
Like a second after I posted I realized that I didn't give you advice.

Get a pressure gauge and check the pressures on all ports, one at a time obviously, as this is happening. In 2nd, you should have pressure on the forward and intermediate test ports.

D
 

·
Registered
Joined
·
7 Posts
Discussion Starter #14
Like a second after I posted I realized that I didn't give you advice.

Get a pressure gauge and check the pressures on all ports, one at a time obviously, as this is happening. In 2nd, you should have pressure on the forward and intermediate test ports.

D
Thanks Darrin, I will definitely test those ports. So far it's been hard to recreate the issue on the street. Going to put it the dyno to see if we can figure it out.
 
1 - 14 of 14 Posts
Top