M52b28 Hard 5500 Redline and P0600

[Steez30]

Recently completed a M52 Swap in my 1989 E30 previously 325is.

Swap went very smoothly and I thought all was well while driving but i noticed that when i drive the car, the first time i do a pull it will allow me to reach the 7200 redline as coded. but the second, Third, and so on time i try and pull no matter the conditions it has poor acceleration and a 5500 firm redline.

Its as if when the car is cold I can redline at the expected levels and once the car reaches temperature it wont allow it anymore.

Throwing 11 codes as of now 6 present and 5 pending

They are as follows


(x2) P0443- Evap Emission system Purge control valve circuit

Explanation: SAP not found (should have been deleted)



(x2) P0141-o2 sensor heater circuit bank 1 sensor 2

Explanation: (post cat o2, should have been deleted)




(x2) P0600- Serial Communication Link (CRITICAL)

Explanation: TCU not found? or something else




(x2) P0111-Intake Air temp Sensor 1 circuit Range/ Performance

Explanation: Air temp Gauge that is in rubber boot sending bad signal (replaced and no code anymore)



P1421-Manufacturer Control

Explanation:This code indicates a problem with your secondary air system. SAP Pump
(Should have been coded out)




P1423-Manufacturer control

Explanation: This code indicates a problem with your secondary air system. SAP pump
(should have been coded out)



P1145-Manufacturerer Control

Explanation: field tank vent (Evap should have been coded out)

As stated in most of these codes they should have been removed from the ecu entirely by the tuner who removed ews from my DME. However there are still checks being run for them. only one that "causes limp mode" is the P0600. Has anyone delt with this and what was the fix?

In all seriousness if someone actually helps me fix this I will give you a 3d printed e30 lol

[Northern]

very rusty with MS41, but there's some difference between auto and manual - does it think it's auto?

I think the codes for SAP, Post-cat O2, evap, etc. need to be suppressed in the tune as well as the functionality disabled via the control bits, maybe the tuner only did the first half? or not at all...

About the lack of info with some of those codes... this isn't going to fix anything, but should reduce the ambiguity of the "Manufacturer control" stuff:

If you can convert the OBD2 Poo codes into bmw DTC codes, there's a DTC list here:

https://sites.google.com/site/openms41/reverse-engineering/documentation/diagnostic-trouble-codes-dtc

Or in 2026 you can just throw the Poo code in bmwfault.codes (Made by Matt P of this forum and e30tech... can't remember his username):

https://bmwfault.codes/

[Steez30]

Thanks for the Info Northern,

What was requested of the tuner was
-EWS Flash
-Post Cat o2 Delete
-Evap Delete
-Redline Increase
-Manual Code conversion (Ecu is from Automatic donor car)

would it still throw codes if those were deleted. and it does seem like the P0600 code refers to the ECU trying to Connect with the TCU and not being able to. Could I re-tune everything and try to fix those errors?

[Northern]

I can't remember if the auto to manual stuff is just a control bits change or if it's a different flash between auto and manual. I have a few MS41 but all of them are from manual cars.

The redline could also be from VSS, 5500rpm sounds correct for that at least.
Basically two issues -
Major: If VSS isn't hooked up to the ECU, it'll error out and limit to 5500RPM.
Minor: Since the E36 uses the 48 tooth ABS signal for vehicle speed, e30 uses the 9 tooth diff sensor, the signal it receives is way too slow, and may trigger that same error at some point. I think most people never have this issue, a few encounter it at some point.

Hooking up the VSS signal is reasonably easy, but some E30s have it through the C101-X20 adapter, and some have it through the connector in the glovebox (C104?)
VSS factor is correctable in the tune, there's a thread buried in the romraider forum about it the factor.

This won't fix your other codes, BUT it might fix your limiter (unless the TCU code also triggers it)
Some of these codes may not trigger a CEL, so maybe they aren't a problem for you.

I'd probably double check this first though.

[DesertBMW]

who ever tuned your MS41 just did EWS delete and nothing else.

[Steez30]

I thought my VSS was set up correctly since i have a late model e30, however upon viewing the x20 plug where my signal should be flowing through I noticed that the pin is not there. Apparently on the automatic engine harness the vss goes through the egs which is a different connector that was cut off since its not entirely needed? so that could be the issue, but still not ruling out that the guy who tuned my ECU did it entirely wrong. Does anyone know anyone that tunes these/ would verify mine was done right?

[Northern]

I'm not sure who the go-to people are these days.
The tune can be read-locked, but if he really had no idea what he was doing, then I doubt he could/would do this.

[TobyB]

I too was thinking VSS- can you see live data in MS41?
That would be a quick way to check. I've had it get me in MS43...
and also with a -524 E30 dme.

P0443- Evap Emission system Purge control valve circuit

that's grumping that you don't have a purge valve on your charcoal canister.
I'll bet you don't have a charcoal canister, either, do you? ;)
just another ms43 thing that took too long to fix...

t

[Steez30]

Wanted to provide an update because my car is now more or less drivable. I'm not sure.

I followed the route of VSS and used online resources to find the pin on the ecu connector x6001 or whatever and the pin on C1 into the cluster and connect the two. Nothing changed while driving. I also made sure to clear codes before i drove so not sure if VSS was an issue. Apparently with the condor speed shop harness adapter it accounts for VSS so i may have just added a wire for no reason.

my next idea was to get a new ECU and have it flashed tuned and messed with by a different person.

Found a new tuner who knows what he is doing. so i decided to order a whole ecu and tune from him and compare the two.

Came in yesterday and i installed it in the car. immediately i noticed a difference in the way it drove and idled.
some good and some bad.

While driving i noticed that the car would not accelerate quickly- I would press the throttle and it would like hang for a few seconds then go. was weird. it sounds like my engine is trying to run but it cant then it snaps out of it and runs.
the good is that there was no redline-
however there are still codes, but they are different. which is perplexing that nothing has changed and the two ecu throw out different codes.

The New Codes:

p0500: Vehicle Speed Sensor A

p0340: Camshaft Position Sensor

p1145: Solenoid valve running losses control circuit

p0111: Intake Air Temp sensor

p0141: o2 sensor

p0161: o2 sensor

Any thoughts? i went ahead and ordered a camshaft sensor although i know anything but oem is gonna potentially not work or only work for a few hundred miles. but id rather know this engine can run right as opposed to never know

Also if anyone knows how to wire up a vss let me know. I must have got it wrong the first time?

1989 325IS body and 1996 328i convertible Automatic donor. I heard something about vss going to a weird place on the auto harness.

[Northern]

p0500: Vehicle Speed Sensor A - Sounds like it still doesn't have VSS

p0340: Camshaft Position Sensor - 3 options:
1: unplug the cam sensor from the harness, pull back the boot and see if the wire insulation is toast - if it is, you can try to re-coat them with liquid electrical tape or replace the sensor.
2: aftermarket sensor which often don't work.
3: sensor is bad.

p1145: Solenoid valve running losses control circuit - Missing 3/2 way valve (with the Fuel Pressure Regulator, hopefully you are running a different fuel rail?) This should be deleted in the ECU.

p0111: Intake Air Temp sensor - IAT disconnected or broken?

p0141: o2 sensor - I think these are Post-Cat O2 heater circuit related

p0161: o2 sensor


MS41 X20 pinout (same across M52/S52 E36) (by Kadunza, can't remember their r3v handle)


He never made M20 1988+ pinout diagrams like this, only early ones.
My notes for my '88 (325e) say C101 Pin 14 is VSS. Black/White on the engine harness side, Blue/White on the body harness side
My old notes for my '90 are terrible and don't even have it listed, but I found some '90 pinouts in old posts that also say pin 14, so '89 is likely the same.

[Steez30]

p0500: Vehicle Speed Sensor A - Sounds like it still doesn't have VSS- Yeah need to hook this up i suppose- or maybe my attempt at hooking it up accidentally deleted it?

p0340: Camshaft Position Sensor - 3 options: - yeah the sensor has no covering on it anymore. kinda crazy that it deteriorated that badly even with a cowl. ill try to repair but i have a new sensor coming in the mail. well try both routes but id like to keep the oem one.
1: unplug the cam sensor from the harness, pull back the boot and see if the wire insulation is toast - if it is, you can try to re-coat them with liquid electrical tape or replace the sensor.
2: aftermarket sensor which often don't work.
3: sensor is bad.


p1145: Solenoid valve running losses control circuit - Missing 3/2 way valve (with the Fuel Pressure Regulator, hopefully you are running a different fuel rail?) This should be deleted in the ECU. - Running a deatschwerks FPR with oem fuel rail- seems to run fine and hold pressure at idle and startup

p0111: Intake Air Temp sensor - IAT disconnected or broken?- Just replaced this with a new one- when i googled this code it was saying MAF could be dirty/ bad but not causing the car to run bad apparently so not too concerned.

p0141: o2 sensor - I think these are Post-Cat O2 heater circuit related - Yeah not important for now.

p0161: o2 sensor


My biggest concern is the first ECU that was in this car let the car run and threw the codes i started this post with and the new ecu is throwing different codes. getting a laptop and d can kline to try and view live data.

[TobyB]

A bad cam sensor will certainly cause drivability issues like you're having...

t

[Northern]

I don't know what it is about the cam sensors on the M52s but the insulation seems to turn to dust. I've had good luck with the liquid electrical tape route - I let a layer harden on the wires so they couldn't make contact and then put a fresh big blob in before replacing the boot.

FPR setup should be fine it ifs 3.5bar, just needs the running losses or 3/2 way valve deleted in the tune. Same with the Second O2 - basically these can be turned off, but the heater circuit DTCs need to be disabled separately.

VSS - check what you did against the X20 pin 9 to C101 pin 14 stuff above - check the wiring colours to make sure they're not going straight to power or GND first. I'm only like 75% confident about the E30 side of that pinout...

Live data will help with the IAT, could be sensor or wiring.