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Discussion Starter #1
What role does a MAF play, if any, in the shifting process of a 722.4 trannie?

If the MAF were failing could it cause delayed shifting or flaring?

Car idles fine however.

Thanks.

1994 128k on the clock and I'd guess original MAF, I haven't replaced it in the 7 years I've owned it.
 

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MAFaffecting shifts

Ya know, now that to mention it I have heard people complain about MAF affecting shifting too.

You can now attack your problem from any direction, you are surrounded!:D

If your MAF is that old I would just start there! Those buggers cause more Phantom problems than anything else by fooling the computer.

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #4
Ya know, now that to mention it I have heard people complain about MAF affecting shifting too.

You can now attack your problem from any direction, you are surrounded!:D

If your MAF is that old I would just start there! Those buggers cause more Phantom problems than anything else by fooling the computer.

Good Luck!:thumbsup:

C as in 220
I'm going to figure this thing out soon enough!

Thanks for all your help, you've been great.

Tomorrow I will clean the MAF and start from there. I do have a slight fluctuation in idle, but nothing crazy. Hmmm.....
 

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Discussion Starter #5
Also, something I just noticed, is that after the engine is warm (at least an hour of driving) it "jerks" under light throttle off the line. As I'm sifting through this PDF of the 722.4, my symptoms seem to be pointing to that modulator needing adjustment.
 

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Also, something I just noticed, is that after the engine is warm (at least an hour of driving) it "jerks" under light throttle off the line. As I'm sifting through this PDF of the 722.4, my symptoms seem to be pointing to that modulator needing adjustment.
CJShade is the modulator man. Now where is that thread?
 

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Discussion Starter #9 (Edited)
Great thread, and what I need.

Does the white cap ("Modulator Cover" seen below) also act as a seal for the modulator? Mine is cracked and I'd bet that if I pry it off, it would crack in two. So I stopped and worked my way back to the 'puter to check first.



(stole your pic btw-hope you don't mind.)
 

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Tranny Pic.

That Transmission looked awfully familiar...:rolleyes:

I may still have my old one if you need it. It doesn't hold any vacuum or fluid back at all. Just a dust cover really.

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #11
I took the MAF apart and thoroughly sprayed cleaner on it. Waited about fifteen and then put it back together and then back in. Idle was butter smooth, with no bumps, but it didn't effect the shifting one iota. Scratch that.

Will make first adjustment tomorrow and will keep you guys posted.
 

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Modulator Discovery

OK,

I went and looked at the old part (Modulator) and learned a great deal!!!

The Stock parts are NOT the same as replacement Modulators. The one in my old thread is a REPLACEMENT Mod. and did not have an adjustable Cap. The Stock ones, and maybe some other replacement Brands, allow you to turn the cap to change the pressure setting. It doesn't get any easier than that. I had replaced my stock one without removing the cap to see how they were different.

Your cap is cracked because someone else has tried to remove it in the car's history. DO NOT remove the cap on the Stock units or they will crack!:eek: I just learned that trying to remove the spare one I have. It can still be used if you need it and it is better than yours.

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #13
Hmm...what do you think I should use to try and turn the cap? Can you turn it by hand?

Do you think the stock one also acts as a seal then? Or no?
 

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Modulator Adjusting

Dude,

I hope I caught you before you broke your cap off!

The cap is still just a dust cover but it also has a little O-ring to keep water out of the adjuster screw.

All you have to do is rotate the cap (see the big tab in the Pic.) and that changes the pressure. There is a little T screwdriver dealie that adapts to the white cap inside. Mark where you start with a Sharpie pen so you have a referance point. It doesn't take much of a turn to change the pressure a great deal. If I remember right clockwise is up and C/C is down. You probably want to increase the pressure to fix your flashing. It's best to use the gauge since the pressure is supposed to be pretty precise.

Good Luck!:thumbsup:

C as in 220
 

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Mod. Adj.

It turns pretty easy by hand. The total range of adjustment is only maybe 120 degrees and you hit the stops. It doesn't take much to effect a big change.

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #17
Popped the cap off and it was not cracked. Looked different last night with the shop light I suppose. Turned it one full revolution clockwise and while the shifts are much firmer (which I like) it didn't solve my long 2-3 shift or my flaring in low speeds.

Frustrating.

I called Mercedes shop and they claim there is no k1 spring kit for this car. Although I thought this transmission 722.4 has a k1 spring that causes the 2-3 shift issues.

Grrrrrr..............
 

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Hard to tell...

It's hard to tell without a gauge what pressure you are operating at. You may not be there yet. You know your Mod. could be bad too.............. Won't know without the pressure test.

Did you try disabling the Upshift Delay circuit to see if it's that thing?

That Shift Kit deal you P.M.ed to me might be your answer yet. I don't remember if the front of the valve body had the same stuff on it the Pic. had or not. It will cost you about 7 quarts and a Shift Spring Kit to find out.:D

Good Luck!:thumbsup:

C as in 220
 

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Popped the cap off and it was not cracked. Looked different last night with the shop light I suppose. Turned it one full revolution clockwise and while the shifts are much firmer (which I like) it didn't solve my long 2-3 shift or my flaring in low speeds.

Frustrating.

I called Mercedes shop and they claim there is no k1 spring kit for this car. Although I thought this transmission 722.4 has a k1 spring that causes the 2-3 shift issues.

Grrrrrr..............
It is called the MERCEDES 722.6
PART NUMBERS 68942-07K, F-68942-TL7
Pressure Regulator Valve Kit
Pressure
Regulator Valve
Kit
68942-07K
1 Pressure Regulator Valve
1 Inner Spring
1 Reamer
F-68942-TL7
1 Guide Pin
1 Reamer Jig
1 Reamer

PM me your info and I will send you a PDF
 

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Discussion Starter #20
It's hard to tell without a gauge what pressure you are operating at. You may not be there yet. You know your Mod. could be bad too.............. Won't know without the pressure test.

Did you try disabling the Upshift Delay circuit to see if it's that thing?
Upshift delay was ruled out a while back. But....tell me how to disable it again please.

Next step is to pressure test. I really should get a vacuum gauge too.


That Shift Kit deal you P.M.ed to me might be your answer yet. I don't remember if the front of the valve body had the same stuff on it the Pic. had or not. It will cost you about 7 quarts and a Shift Spring Kit to find out.:D

Good Luck!:thumbsup:

C as in 220
Yea, counting the gasket maybe 20 bucks or so. I've serviced this trannie several times so I'm familiar with the process. That should make it fairly easy. Smelled the fluid the other night, and it was still red and didn't smell especially burnt.

Thanks again for the help.

It is called the MERCEDES 722.6
PART NUMBERS 68942-07K, F-68942-TL7
Pressure Regulator Valve Kit
Pressure
Regulator Valve
Kit
68942-07K
1 Pressure Regulator Valve
1 Inner Spring
1 Reamer
F-68942-TL7
1 Guide Pin
1 Reamer Jig
1 Reamer

PM me your info and I will send you a PDF
PM sent, thanks bud.
 
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