ITB Kit and Harness (REDUX Racing)

[It's Soda Not Pop]

What's wrong with your stock harness? Are you planning to use PNP DME ?

Obviously that harness doesn't replace the entire car harness, just DME to C101 from what it shows. I use PNP DME with ITBs and successfully modded oem harness to remove chasis ground from all sensors (just like Rama did in his ECUmaster harness). All it took a couple of splices in OEM harness as there are plenty of wires and done. Reversable as well if you ever go back to 100 % OEM setup. No need to remove/slice the entire engine harness as well, All ground connections for sensors are 7-10" up from DME connector, everything is easily accessible. OEM injector harness already have all temp sensor conductors separated so no need to mod that. Just a few splices by DME connector and done

All the wiring in these cars are 30+ years old. Brittle connectors. A brand new harness and a more modern ecu is piece of mind plus options when it comes to modding. I'm not a purist per se. My current e30 isn't a collectors item or meant to be put up and never driven. I drive my e30, I like modifying it. If this company makes a good product where I could potentially avoid some gremlins, then I'm all about it. Also I used to work on aircraft and the one I thing I do not enjoy is wiring. I can do it, but I hate it. So I'll let someone else do that.

[zaq123]

All the wiring in these cars are 30+ years old. Brittle connectors. A brand new harness and a more modern ecu is piece of mind plus options when it comes to modding. I'm not a purist per se. My current e30 isn't a collectors item or meant to be put up and never driven. I drive my e30, I like modifying it. If this company makes a good product where I could potentially avoid some gremlins, then I'm all about it. Also I used to work on aircraft and the one I thing I do not enjoy is wiring. I can do it, but I hate it. So I'll let someone else do that.

I don't believe there is a complete e30 harness that will replace your entire harness. Headlight/AC/Fog lights etc etc external connectors (what is typically old and crusty) would still need your attention and likely they are still available from BMW. Conductors itself in these cars is a top notch quality unlike anything eco friendly soy based crap what's made today. Regarding modern ECU: there is no question that better options are available, including PNP ones (hence the need to separate sensor grounds from chassis as I explained earlier)

[It's Soda Not Pop]

I don't believe there is a complete e30 harness that will replace your entire harness. Headlight/AC/Fog lights etc etc external connectors (what is typically old and crusty) would still need your attention and likely they are still available from BMW. Conductors itself in these cars is a top notch quality unlike anything eco friendly soy based crap what's made today. Regarding modern ECU: there is no question that better options are available, including PNP ones (hence the need to separate sensor grounds from chassis as I explained earlier)

Oh yeah I know this harness is mainly to run the engine. Maybe it's just me being me. I like to put brand new stuff in the car it gives me peace of mine. Even if I'm just money on fire. 😆

[e30davie]

I don't believe there is a complete e30 harness that will replace your entire harness. Headlight/AC/Fog lights etc etc external connectors (what is typically old and crusty) would still need your attention and likely they are still available from BMW. Conductors itself in these cars is a top notch quality unlike anything eco friendly soy based crap what's made today. Regarding modern ECU: there is no question that better options are available, including PNP ones (hence the need to separate sensor grounds from chassis as I explained earlier)

You are a DIYer like me, but the others are perhaps not to keen, so happy to buy off plug and play stuff. I made a complete new harness to put my mega squirt onto an Early m20 car (Jetronic, not motronic). I just bought all the bosch connectors some some rolls of wire and wired it all up. In my opinion (and probably yours too) is that it wasn't that big of a deal. But its certainly above the knowledge of most I'd guess.

[digger]

why are you guys modifying the grounding system that stock harness has?

[zaq123]

why are you guys modifying the grounding system that stock harness has?

oem setup has no sensor grounds except for oem AIT pin 26. Alll but AIT grounds for sensors are connected to chassis and it's understandable considering the primitive nature of M1.3. Looks like they only cared about very clean signal from AIT sensor and didn't care if others were noisy.
M1.3 doesn't rely on/adapt to accurate sensor measurement for the control except AIT sensor (OEM e30 TPS is basically on/off switch, temp sensor doesn't need to have super clean signal as the table resolution is low)

This is not the case with more advanced/modern ECUs where the signal clarity is important (without going into signal ground vs chassis ground explanation).
For example ITBs absolutely need consistent and clean signal from TPS. Chassis grounded sensor can't ever deliver that. Clear signal for the temp sensor and tables it affects is important as well....bmw finally realised that in e36. Wiring IAT sensor is easy as AIT ground is already isolated to ECU, it is an actual signal ground in stock e30 harness (thank you BMW for not running it through chassis ground)

[e30davie]

To be honest I just followed this,

https://www.msextra.com/doc/general/ms2external.html

And the sensor ground is seperated out, but there is that note that ground pin 1, 2, 7 19 are all joined together internally anyway. maybe other ecu's separate the "Sensor ground" from the "power ground" but the mega squirt link suggests it doesnt? For what its worth all my sensors work great wired up like this (air temp, water temp, tps, crank sensor)

[zaq123]

To be honest I just followed this,

https://www.msextra.com/doc/general/ms2external.html

And the sensor ground is seperated out, but there is that note that ground pin 1, 2, 7 19 are all joined together internally anyway. maybe other ecu's separate the "Sensor ground" from the "power ground" but the mega squirt link suggests it doesnt? For what its worth all my sensors work great wired up like this (air temp, water temp, tps, crank sensor)

Exactly. Crank sensor and Air meter are already separated by oem design. Not sure if you have ITBs. As I mentioned, ITBs really need a consistent and reliable signal from TPS. I actually use Hall effect VARIOHM TPS sensor for this. Coolant temp sensor clarity is a bonus as well for any modern ECU table resolution.

7" up the OEM harness from DME connector and all these concerns are easily solved by removing the chassis tap S701 (wire from the strut tower) and tapping TPS and coolant grounds into pin 26 wire. Voilà....you got yourself true sensor grounds which are grounded only in ECU and isolated from all that chassis ground interference. Something that BMW started to implement with Motronic 1.7


https://www.r3vlimited.com/board/for...the-harness

[digger]

oem setup has no sensor grounds except for oem AIT pin 26. Alll but AIT grounds for sensors are connected to chassis and it's understandable considering the primitive nature of M1.3. Looks like they only cared about very clean signal from AIT sensor and didn't care if others were noisy.
M1.3 doesn't rely on/adapt to accurate sensor measurement for the control except AIT sensor (OEM e30 TPS is basically on/off switch, temp sensor doesn't need to have super clean signal as the table resolution is low)

This is not the case with more advanced/modern ECUs where the signal clarity is important (without going into signal ground vs chassis ground explanation).
For example ITBs absolutely need consistent and clean signal from TPS. Chassis grounded sensor can't ever deliver that. Clear signal for the temp sensor and tables it affects is important as well....bmw finally realised that in e36. Wiring IAT sensor is easy as AIT ground is already isolated to ECU, it is an actual signal ground in stock e30 harness (thank you BMW for not running it through chassis ground)

mine is a plug and play ECU (with patch harness) and i don't think anything was modified on install regarding grounding. My TPS is super clean and consistent but only after i went to a hall effect type sensor as i used to get temperature drift with the OEM wiping style. The air temp and coolant temp is fine they arent anywhere near that important as TPS.

I plan to get a new ECU mine is early 2000's tech so i will discuss with the installer.

[zaq123]

mine is a plug and play ECU (with patch harness) and i don't think anything was modified on install regarding grounding. My TPS is super clean and consistent but only after i went to a hall effect type sensor as i used to get temperature drift with the OEM wiping style. The air temp and coolant temp is fine they arent anywhere near that important as TPS.

I plan to get a new ECU mine is early 2000's tech so i will discuss with the installer.

it's like anything else....would one be ok with 720p resolution? sure. 1080p look better? no doubt. Ask the installer about chassis grounds for sensors vs signal grounds. Considering how easy it is to correct in the stock harness, it was no brainer for me.

I believe RHD Rama is on the same page as me hence his M20 harness for ECUMaster (no explanation but he mentions those benefits at around 0:25 of the video)

https://www.youtube.com/watch?v=FxyLBQQP86s

[e30davie]

Nah no ITBS here. Just standard M20b23 with individual coils (no distributor) - though i do have a proper variable TPS wired up like that diagram. I suspect there some sort of isolation inside the mega squirt so that the grounds are separated enough so interference isn't transferred to the sensor ground. as like you say "sensor ground" should be separate to "power ground".

If I ever run into alot of spare money (that the wife doesnt know about..), I would like to do do the same thing again but with a more advanced ECU (Id like an Emtron...), get their flying lead and relay board kit and make the loom all new as per the manufactures recommendations. but my cobbled together mega squirt setup works fine for now. Unless someone wants to pay me ill make them one to fund mine.....

[digger]

it's like anything else....would one be ok with 720p resolution? sure. 1080p look better? no doubt. Ask the installer about chassis grounds for sensors vs signal grounds. Considering how easy it is to correct in the stock harness, it was no brainer for me.

I believe RHD Rama is on the same page as me hence his M20 harness for ECUMaster (no explanation but he mentions those benefits at around 0:25 of the video)

https://www.youtube.com/watch?v=FxyLBQQP86s

Can you describe how it is done for the tps ? Do you need to remove harness ?

[zaq123]

Can you describe how it is done for the tps ? Do you need to remove harness ?

You do not need to remove harness. Do you have M1.3? if so, the below is for you.

Since you already converted to TPS, you already have pin 1 and pin 2 swapped (compared to OEM arrangement). I assume you know where TPS GND wire is at this point. It's pin 2 on stock e30Throttle switch ( BRN) which becomes pin 1 on e36 TPS.

TPS ground is BRN wire. You need to remove the glove box, ECU etc so you can see the loom from the ECU connector going to the firewall. There is S701 tap (yellow cap) about 5-7" away from ECU connector.
Carefully expose wiring to ECU connector. Easiest way is probably to unscrew ECU connector cap screws, undo stock tape which will expose the edge of loom sleeve, carefully slice that sleeve up the loom until you get to the yellow cap (S701). S701 yellow cap will have a bunch of BR/OR wires (3 thin and one thick). That yellow cap has all 3 sensor grounds (thin wires for OIL level sensor, coolant temp and TPS sensor), all bunched up and connected to the thick brown wire( chassis ground wire via the strut tower).
You goal is to leave only OIL level sensor grounded to chassis and connect another two (TPS and coolant grounds) to the isolated signal ground. That isolated signal wire would be GY/BU wire of AFM (ECU pin 26).

As a side note : OIL level sensor (that is connected to all these important sensors) is also grounded through its metal housing which makes OEM setup for all these sensors even worse (know anything about ground loops? bad design). So all these bunched up important sensors not only chassis grounded but also have a ground loop which further degrades the signal quality.


Cut that yellow cap off. You can ring out every and of those wires with a multimeter to know which one is which (they were all BR/OR in my harness).
There is also a shortcut if you don't want to undo sensor plugs under the hood and multimeter everything....... after cutting the yellow cap, two of those 4 wires would still read closed on the ground: the thick BR/OR (going to strut tower) and one of thin BR/OR (oil sensor grounded to the engine block by its housing).
There other two (which will no longer read ground) would be TPS and Coolant sensor. If you really need to know which one is which, you will need to ring them to TPS and coolant sensor plugs under the hood.

So ...cut the yellow plug:
1. figure out which thin BR/OR wire is OIL level sensor
2. Oil Level sensor gets spliced back to that thick chassis ground (connected to the strut tower)
2. splice other two: TPS and coolant sensor BR/OR wires to GY/BU wire (AFM ground, pin 26 of ECU)


Now you got all these important sensors (IAT, Coolant and TPS) properly grounded to yourECU's isolated signal ground.

[digger]

You do not need to remove harness. Do you have M1.3? if so, the below is for you.

Since you already converted to TPS from OEM throttle switch, you already have pin 1 and pin 2 swapped and I assume you know where TPS GND wire is at this point. It's pin 2 on stock e30Throttle switch ( BRN) which becomes pin 1 on e36 TPS.

TPS ground is BRN wire. You need to remove the glove box, ECU etc so you can see the loom from the ECU connector going to the firewall. There is S701 tap about 5-7" away from ECU connector.
Carefully expose wiring to EXU connector. Easiest way is probably to unscrew ECU connector cap screws, undo stock tape there which will expose the edge of stock loom sleeve, carefully slice sleeve up the loom until you get to the yellow cap with bunch of BRN wires. That yellow cap has all 3 sensors (OIL level, coolant temp and TPS) bunched up and connected to the thick brown wire to chassis ground them at the strut tower. You goal is to leave only OIL level sensor there and connect another two (TPS and coolant) to isolated signal ground . That isolated signal wire would be GY/BU wire of AFM (ECU pin 26).

As a side note : OIL level sensor (that is connected to all these important sensors) is also grounded through its housing which makes OEM setup even worse (ground loop). So all these sensors not only chassis grounded but also have a ground loop which further degrade the signal quality.


Cut that yellow cap off. You can ring out every and of those wires with a multimeter to know which one is which (they were all BR/OR in my harness).
There is a shortcut if you don't want to undo sensor plugs under the hood: after cutting the yellow cap, two of those 4 wires would still read closed on the ground: the thick BR/OR (going to strut tower) and one of thin BR/OR (oil sensor grounded to the engine block by its housing). There other two which will no longer read ground would be TPS and Coolant sensor. If you really need to know which one is which, you will need to ring them to the sensor plug under the hood.

So cut the yellow plug:
1. figure out which thin BR/OR wire is OIL sensor
2. Oil Level sensor spliced back to that thick chassis ground
2. splice TPS and coolant sensor BR/OR to GY/BU of AFM (pin 26)


All important sensors (IAT, Coolant and TPS) are now properly grounded to ECU isolated signal ground.

thanks i will digest when i get a chance. i will be removing dash soon so this might be easy to do then

[zaq123]

thanks i will digest when i get a chance. i will be removing dash soon so this might be easy to do then

just to be clear, this firewall harness entrance/ECU loom is way below dash. Those pictures have dash already installed. However I'm not sure about how accessible this area is in RHD e30s