The Blazer is getting about 14mpg - torque converter question

[AJMBLAZER]

Yep, The Blazer is getting around 14mpg. Narrow 32's, seemingly well running C-code 6.2L with J-code intake, 700R4, 3.73's, a heavy right foot, no tach, and around a 40 mile commute with at least 60% of that being at 60-70mph speeds.

I'm fairly sure the torque converter is NOT locking up. I drive around in D and then around 50mph shift it manually into OD. If I don't do this it tries to shift into OD around 35mph unless I have the hammer down hard. There's the rpm drop as it goes into OD but I swear I never catch the other drop as the torque converter does it's thing. Just rumbles along at the same or increasing rpms.

How much efficiency would I be loosing due to not having the TC lock up?

When I put the J code intake on everyone said just cap off and remove the various vacuum lines and the solenoids on the back D-side corner of the engine. Now I'm wondering if those had to do with the TC?

I do recall one guy mentioning running a switch to turn his TC on and off as he manually went into and out of OD. Anyone doing this and how would I go about setting this up?

 

[AJMBLAZER]

 

[longbedder]

I've got a manual lockup switch in mine. I simply put a rocker switch for manual control, but it's interrupted by the brake light switch so the TC unlocks when the brakes are applied - you have to use a relay to do this.

I pretty much followed the schematic here, but I don't have the optional vacuum switch, and therefore only have one wire going to the trans in pin A.

In stock configuration, your Blazer probably had a sensor on the side of the injection pump with electrical connections and/or vacuum lines (to sense throttle position). It would have used the electrical connections for a 700R4 and vacuum for a TH400. The purpose is so that the TC would unlock near full throttle. I bypassed that on mine.

FWIW, it sounds like TC lockup is not your only problem. I would check and make sure that the TV cable is set correctly - there's a good chance it got messed up when swapping intakes, and the consequences could be dire if you let it go. Article here: http://www.tvmadeez.com/article/index.php

 

[AJMBLAZER]

The TV cable thing is on my list. Don't remember touching that during the intake swap though. I only caught about half of what they wrote there though. Definitely written for someone who knows wtf they are doing.

I think I'm going to invest in a Tiny Tach this paycheck. I SWEAR I felt the TC unlock the other day while slowing from 70 to 55. So now I'm doubting myself and curious.

 

[longbedder]

Here's the simple version of the TV cable story:

1) Drop the pan
2) Find the steel plunger in the valve body that moves when the TV cable moves.
3) At zero throttle, the arm that moves the plunger should be juuuuust barely touching it. At the first hint of throttle actuation, the plunger should start to move.

4) At full throttle, the plunger should be about buried (flush) with the bushing that it rides in.

3 & 4 depend on the correct cable setting and the correct throttle arm geometry (the radius from the throttle pivot to the cable attachment point).

 

[AJMBLAZER]

So I have to drop the pan to do this?

Funny how no one else ever mentions this.


**** I hate automatics. I can now see why there's that Transgo kit that eliminates the TV cable assembly.

 

[kennyw]

So I have to drop the pan to do this?

Technically, no. You only have to adjust the cable from the motor. Push in the button, go to WOT, then release the button.

Dropping the pan and watching the movement is just the best way to make sure you got it 100% correct.

 

[AJMBLAZER]

Ah, okay. Well, might plan on doing that when I drop the pan, which is increasingly getting sooner. Put it on the list...

 

[longbedder]

So I have to drop the pan to do this?

Funny how no one else ever mentions this.

Most (95%) of people don't understand and/or don't care enough about what's actually happening. Alot of problems crop up because of that. I'll also say that a 700R4 requires a deeper degree of understanding than a TH400 or TH350.

Hating automatics is usually due to not understanding them. This is't a jab at you - I did not understand them either for a very long time.

Dropping the pan not only gives you the proper answer in this situation, but it also forces a fluid change (which is never a bad thing for an auto). When it's all said and done, a pan drop is super easy.

 

[AJMBLAZER]

I just dislike autos. Always make me nervous whenever they shift funny or do something odd. Not a big fan of the power loss either. Both my trucks have a 5 speed with OD in their future somewhere. Sticks are just better except for the effort to operate them...which I enjoy.

On another site I was told to basically just release the holder clip thing, slide the cable all the way back towards the firewall, reattach the clip there, then put the pedal to the floor. Done and adjusted. I may just do that today and see how it goes and then try to do a pan drop soon.

 

[Greg Ducato]

Two basic rules of tv cable adjustment apply to every situation. The cable should have about one and an eighth inches total travel from idle to wide open throttle in a straight line pull, and the cable should be as tight as it can possibly be at wide open throttle. If these two parameters are in place then you will be OK.The self adjusting cables seldom are, and in most cases too much cable slack will ensue when you put the throttle to the floor, especially with an old cable. Always best to check that the cable is as tight as can be at wide open throttle when you are finished.