M20B25 with a ZF 4HP22 revs only up to 5500 in S mode after a HG

[Mordan]

Hello,

So back then I did a HG. Before that I could rev up to redline 6200 without a hitch.

After the HG job which I did all by myself, I noticed that it would always change gear at around 5500. Has anyone experienced this before? The fluid level is correct and a refill was done. Oil color is good.

I didn't drive the car much but now I want to fix this problem because I'm driving it again.

I wanted to check my TPS which is a 6-pin round connector which I'm told has both a potentiometer and the idle/wot switches inside and a "rehostat' (???) to send some data to the tranny.

The idle click is quite crystal clear. The WOT click is more muted. I wanted to do some multimeter checking but couldn't find the values for this 6 pins connector.

I have already checked this nice page I'd trust the BMW shop manual first. but it is missing the symptoms page. Does anyone has it?

Mordan.

[myles]

If your car uses the non-electronic controlled transmission (you don't have a sports, economy switch) I would guess that the tension on the kick down cable is wrong. If you've got the electronic transmission, I've got no idea.

[Mordan]

If your car uses the non-electronic controlled transmission (you don't have a sports, economy switch) I would guess that the tension on the kick down cable is wrong. If you've got the electronic transmission, I've got no idea.

it is in the title happens in S mode. So I do have a sports-economy-123 switch.

[Mordan]

Hello, I found some info about testing the 6 pins connector. Still any comment is appreciated about the 5500 rev limit.

Pin 1-black wire-5volt in
Pin 2-shielded wire-ground
Pin 3-yellow wire-signal out
Pin 4-ground
Pin 5-WOT switch
Pin 6-Closed switch

From Motronic 1.3 and auto TPS - Page 2 - BMW E9 Coupe Discussion Forum
I personally I won't touch a used TPS because I have tested so many bad ones. Usually it is corroded WOT connections inside.

To test- pull the rubber boot off and test for continuity between the brown/blue and brown/orange wires for your idle signal.

test WOT circuit by checking for continuity between brown/black and brown/orange.

This test is done with the plug OFF! If it makes it easier for you- with the plug off, 12:00 pin is brown/black, 2:00 pin is brown/blue and 10:00 pin is brown/orange.

Attachment 7687

I will check this ASAP.

[myles]

Back to reading 101 for me.

[632 Regal]

Cam timing off 1 tooth?

[Mordan]

Hello

I went underneath the tranny and it says 4HP22.

so I have a euro version with 4HP22 AND Sport Mode and the TPS with the 6 pins potentiometer.

I drove a little without the TPS connected. Idle went up to 1200 and car drove nicely except without kick down function and much slower acceleration. No Overdrive. Slow gear shifting.

So the TPS seems to work.

The Cam timing off 1 tooth is indeed a possibility. But otherwise the engine idle is smooth and everything is fine. So I would guess a cam timing off by one tooth would be generating other symptoms than just the too fast gear shifting at WOT. I did the HG myself and was pretty cautious with the timing belt.

I noticed the WOT shifting in Economy mode is 4500. In my memory it was around 5300. It is like WOT shifting in either E or S mode are now faster. Both have lost like 700-800 RPM.

[whiskychaser]

Rheostat is just a posh name for a variable resistor. It is similar to what you have in the volume control of your radio. IIRC the throttle pot is linear whereas the radio ones are not. There are a few different 4HP22s around and so maybe Google Zf Tech Guide.pdf. (7138kb) If you cant find it, PM me your email address and I will send if to you

[Mordan]

Found it! thx whisky

Great document.

Since my car is from 1987, it seems I have a 5 solenoid model. There is a table with resistance values . That's nice.

But the shifting is still controlled by an ECU which controls solenoid 1 and 2 for a total of 4 combinations.

Gear 1 : MV 1 on MV 2 on
Gear 2 : MV 1 off MV 2 on
Gear 3 : MV 1 on MV 2 off
Gear 4 : MV 1 off MV 2 off

So it is pure electronic control for automatic upshifts from 1st thru 4th and automatic downshifts from 4th thru 1st
gears.

The solenoid are obviously good. The speed output sensor could be a possibility.