[e46lucas]

i got a 99' 328i with the m52tu meaning i have the weird ass half cable half electronic throttle body.
my original tps sensor went to sh!t so i had to get a used TB and couple months pass by and now this one is done, getting constant EML and limp mode from throttle issues and i was thinking if its possible to swap a m54 TB onto the m52tu hoping maybe that would help with the terrible m52tu TB
anyone know how to or if its even possible to swap the m54 TB to the m52tu?

also when the car goes to limp mode i reset the throttle and reset the codes and it drives fine for ~15 miles and then happens again, goes into limp mode for the same thing

 

[Bali]

Not possible to swap just the TB, because the DME, wiring, etc., all expect that type.
You would have to also swap to a matching DME, such as MS43, which is a much bigger project.

Have you read through all the existing M52TU TB threads on here? There are many.

Search results for query: M52TU throttle

www.e46fanatics.com

 

[Effduration]

Been there and done that.

It is not likely you have another bad TB. What is likely is that there is corrosion, etc in the stupid round 10-pin connector which points toward the rear of the car and which has no rubber to protect the connections from the elements and the air stream around the engine...

As you may know the Throttle body /DME in the M52TU engine is extremely sensitive to changes in resistance, voltages, etc. A deterioration in the wiring is likely a cause of your issues.

you have a couple of options.
1. Spray de-oxit or something similar in the back of the connector - might or might not work
2. Replace with a used M52tu harness - might last for a while
3. Replace with a new harness - part# avail on RealOEM. Expensive and likely not avail.
4. Replace just the connector as outlined here:

Electronic Throttle Faults & Repair

Diagnosing electronic throttle body faults and replacing its connector plug on 99-00 BMW 5 series.

www.frankies-bmw.com

There are people who have tried - with mixed success - to wire in an M54 Drive by wire pedal. Usually done as part of an upgrade from M52TU to M54. Not easy, and full of risk of add'l problems - Not recommended.

323Ci (M52tuB25) to M54B30 Complete Conversion, with...

As I mentioned in my header build thread, http://forum.e46fanatics.com/showthread.php?t=829844&highlight= a buddy of mine was DD'ing. Long story short, I egged him on to drive the car hard and he money-shifted it. Based on gear ratios and engine speed when he shifted, I calculated 8500 RPM. I...

www.e46fanatics.com

 

[Sapote]

i had to get a used TB and couple months pass by and now this one is done, getting constant EML and limp mode from throttle issues

Most of the time this issue was caused by the TB butterfly valve seized and doesn't move freely. Clean up the TB barrel around the valve should fix it.

 

[Effduration]

Most of the time this issue was caused by the TB butterfly valve seized and doesn't move freely. Clean up the TB barrel around the valve should fix it.

OP has already replaced his TB once...So were both butterfly valves seized?
It's fine to clean the throttle body, I just wouldn't manually open and close the main vane. Treat it gingerly.

 

[Sapote]

OP has already replaced his TB once...So were both butterfly valves seized?
It's fine to clean the throttle body, I just wouldn't manually open and close the main vane. Treat it gingerly.

10 years ago when my wife cracked the cylinder head and hydraulock the engine with coolant in cylinders, after I fixed it and took a drive test. I was going around 35 to 40 mph and everything was fine until I got faster before entering the FWY, then hell broke loose with limping mode and barely moving at 5mph going home. It turned out the ICV was working all the time to 35 or 40 and when the main TB butterfly needed to open for higher speed then the DME detected it was jammed and threw me into limp mode. Within 15 minutes I have the TB out and cleaned the inside barrel to free up the butterfly. The moisture from the coolant in engine corroded the TB aluminum barrel and locked up the butterfly.

 

[dmax]

I'd remove the tb and icv, clean both well with tb cleaner, replace gaskets, lube throttle cable...and make sure the icv connection is on right. It's a pitb two-stage connector that will make you think it's on okay, when it's not.

Turn icv every direction you can and spray then drain fluid until you hear the valve brightly clicking.

 

[Effduration]

10 years ago when my wife cracked the cylinder head and hydraulock the engine with coolant in cylinders.....The moisture from the coolant in engine corroded the TB aluminum barrel and locked up the butterfly.

Most of the time this issue was caused by the TB butterfly valve seized and doesn't move freely. Clean up the TB barrel around the valve should fix it.

Sapote a cracked cylinder head that leaks coolant into the intake and throttle body is pretty damn rare. Is that what made you say "Most of the time" TB Butterfly seized...?

OP should certainly clean his TB - very carefully without manually opening the vane. But I am willing to bet he has the much more common M52tu throttle body wiring issue.

 

[Sapote]

Sapote a cracked cylinder head that leaks coolant into the intake and throttle body is pretty damn rare. Is that what made you say "Most of the time" TB Butterfly seized...?

No coolant leaked into the TB as the engine never rotated backward, but the collected hot coolant in the cylinder -- with IN valves opened -- created high moisture enough to cause condensation in the intake manifold and associated parts, and car not driving for a week this led to seized butterfly valve. Most of the times with M52TU TB issue with limp mode, the butterfly was seized due to corroded barrel due to various reasons, but living in high moisture environment and car not driving often would promote this issue.

 

[nareck]

Any updates @e46lucas ? I am having the same issue for a long time, tried changing TB (used) 3 times. Same issues. The only thing that was changing is how fast it went to limp mode at first I drove for couple of months then weeks, now it fails within 20 minutes...
Thanks @Effduration for the tips I should probably try the 4th tip (Replace just the connector). Just don't want to ruin something which I am not sure is the problem.
Attaching the pics of error codes in INPA I am having in random order:

 

[e46lucas]

Any updates @e46lucas ? I am having the same issue for a long time, tried changing TB (used) 3 times. Same issues. The only thing that was changing is how fast it went to limp mode at first I drove for couple of months then weeks, now it fails within 20 minutes...
Thanks @Effduration for the tips I should probably try the 4th tip (Replace just the connector). Just don't want to ruin something which I am not sure is the problem.
Attaching the pics of error codes in INPA I am having in random order:

I actually disconnected the connector and sprayed some electrical connector cleaner thing from autozoneon both sides of the connector like the side you plug into the throttle body and the side where the wires go into the connector, let it dry and sprayed it again, and when it was dry I plugged it back in and it worked fine ever since

 

[Sapote]

I am having the same issue for a long time, tried changing TB (used) 3 times. Same issues.

You seem to have an electrical issue with with TB, and why the battery reported in one of the pic was 6.43V instead of close to 12v?

 

[NZ00Z3]

A clue from the 112 code. Potentiometer 1 does not have a power supply. It should be 5V. You need to check the voltage at pins 2 to 4 and 1 to 7 at the MDK or there equivalent at the DME end.

Attached is some MDK information I have found on the Interweb over the years. Hope it is useful.

 

[nareck]

A clue from the 112 code. Potentiometer 1 does not have a power supply. It should be 5V. You need to check the voltage at pins 2 to 4 and 1 to 7 at the MDK or there equivalent at the DME end.

Attached is some MDK information I have found on the Interweb over the years. Hope it is useful.

Thanks a lot! That PDF is a gem. First will test the TB then will do the voodoo on the 10-pin connector. Meanwhile found 2 more photos of other error codes from past.
It's annoying how one error code (173) says "short circuit" other (119 from earlier post) says "mecanical error" :-|

 

[nareck]

I've tested one of my "failed" TBs (other one is under the hood yet). There are clear deviations from the PDF provided by @NZ00Z3

Requirements: 1600 - 1000 Ohm, tolerance: 10%
2 & 5 : 1866 - 1228
2 & 3 : 1720 - 977
1 & 6 : 1753 - 1012
1 & 8 : 1843 - 1182

Requirements: 1000 - 1650 Ohm, tolerance: 10%
4 & 3 : 1035 - 1725
4 & 5 : 1040 - 1725
7 & 6 : 1066 - 1758
7 & 8 : 1205 - 1848

I am a complete newbie so I'd appreciate any advice. Are the above measurements enough evidence to be sure that TB is broken?

 

[NZ00Z3]

What are the readings for pins?

• 2 - 4
• 1 - 7

Its a resistance divider circuit, so need the above reading as the starting values.

The information was found on the Interweb some time back. It's likely the readings some owner got when testing a MDK. I would not yet use the numbers as a hard and fast pass/fail test until we get some experience with them. Get me the above requested values and I run them through a spreadsheet for you.

 

[nareck]

What are the readings for pins?

• 2 - 4
• 1 - 7

Its a resistance divider circuit, so need the above reading as the starting values.

The information was found on the Interweb some time back. It's likely the readings some owner got when testing a MDK. I would not yet use the numbers as a hard and fast pass/fail test until we get some experience with them. Get me the above requested values and I run them through a spreadsheet for you.

2 & 4 : 982
1 & 7 : 992

 

[MrMCar]

BMW (and many other manufacturers) strongly advise the use of "Stabilant 22" for applying to the connector pins, both male and female for such instances. It's fooking expensive, but if there's a connection issue with the pins and varying resistance is the root, the Stabilant usually fixes it.

FYI.

 

[Effduration]

BMW (and many other manufacturers) strongly advise the use of "Stabilant 22" for applying to the connector pins, both male and female for such instances. It's fooking expensive, but if there's a connection issue with the pins and varying resistance is the root, the Stabilant usually fixes it.

FYI.

Thanks for this...It sounds a little like a commercial/professional grade De-Oxit. The first google search result on Stabilant 22 came from Boeing....

I think I am going to try it before I either replace harness (with another used harness) or replace pins as suggested above...

Here is a description of Stabilant 22: '

Posthorn | Stabilant 22

"...Its advantage lies not in making new contacts better, but in keeping contacts operating as if they were new, while making old contacts function perfectly despite the ravages of time and adverse environments...."

 

[zurk]

Alternative input from another M52Tu user

Could it be the cause of the EML is the throttle cable itself and not the pin connectors? I’m using an M56 intake manifold (same port size as M54B30) with a Turner adaptor plate mated to an M52Tu throttle body. The manifold is not meant
to be used with the M52Tu TB, more so with a spacer, so TB cable does not sit at
the default location.

I had a couple of events where the TB cable orientation or tension was incorrect on the mount and caused an EML/Limp mode, limited to 50-55 mph.
I don’t remember the exact code, since I was on the road at the time, but had to reach in and slip the cable in such a way it didn’t bind or the cable tension is at an acceptable range. I think there was interference with the bracket that held the sucking jet pump for the brake booster and the code was TB potentiometer error.

This was btw on post Manual 5-Speed swap indicating throttle, even with a cable actuation, is electrically controlled/limited. Much like late 90’s Mercedes but the potentiometer is separate from the TB.

I haven’t had the problem since and switching to Ms43 soon just to simplify the car more.


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