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?

[Robyn]

You definately should be able to feel the converter lockup when that happens.

First before you go to work trying to wire in switches and such, get the rig on a level road and check to see that the converter is actually locking up.

If there is no lockup then you need to find out why.

There could be an electrical issue that is causing no lockup, or the converter clutch is worn out.

There is a thermal switch in the internal wiring setup that can fail but thats a long shot.

Once you get this issue sorted out, the best setup for the converter lockup is lockup kit sold by Transgo.

This installs in the valve body and controls the Lockup hydraulicaly and works real well.

It can be adjusted (Spring selection) to allow the lockup to occur at around 45-50 MPH

The factory setup that allowed the very low speed lockup causes the lockup clutch to take a lot more abuse than it can really tollerate.

The constant in out, in out around town wears the clutch out quickly.

If the clutch is not engaging, I would drop the pan and see whats in there in the way of crap in the bottom.

If there is a lot of crud in the pan, the lockup clutch is likely toast.

Keep us posted.

Robyn

[AJMBLAZER]

Level surface...have you ever been to Kentucky?;) I've been harboring this suspicion for a while and I don't know.

Every now and then the trans will sort of shudder if I'm in OD and trying to give it a little gas, like it's trying to unlock or something.
Then today on the way home from work as I was leaving the freeway I started to coast from around 70mph and as it slowed I SWEAR I felt the TC unlock. Frustrating and making me second guess myself. I really need that tach.

My frustration is I know jack**** about auto trans other than, "they're expensive", "they make me nervous", and "I prefer sticks". I'd REALLY like to swap a NV3500 in some day soon but just not in the cards right now.

How do I test this stuff? I don't know where to start.

How much does the Transgo kit go for?

I need to change the fluid anyway but it is red(ish). I was told the trans was rebuilt 2 years ago before I got it. I have seen stuff that makes me think this is the case...but lord knows if they reused the old TC or rebuilt it correctly/well.

[AJMBLAZER]

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[convert2diesel]

With the truck at a constant speed in OD (or 3rd), keep one foot on the gas and then slightly apply the brakes. Not enough to slow the truck down, just enough to unlock the TC (turn on the brake light). You should notice a slight rise in RPMs, release the brake pedal and you should feel it go back into lock-up after about 3 seconds. Its easier if you do it in OD as this loads up the engine more at speed and will give you a more definitive indication of the torque locking and unlocking.

These trannys are notorious for the TCC solinoid going south. Quick easy fix for about 50 bucks. You do have to drop the pan but then your changing the fluid anyways.

Hope this helps

Bill