Instead of tapping the S52 head for coolant temp sensor...

[matt]

Here is some information that may clear up some issues regarding the temperature sensor when running a 2.8 or 3.2 M52/S52 in an E30.

First, the reason we developed this part. Yes, you can drill and tap your cylinder head and add a second sensor. The only problem with that is that it is risky. If you do go that route make sure whoever is drilling is good. If they aren't, or if they do not set up the head on the mill, you could drill at the wrong angle, creating the wrong plane. This will result in a bad seal between the head surfrace and the sensor. This can lead to leaks or damage to the head.

Second, our mehtod compared to the manifold adapter option... We like to have our sensor in a constant coolant flow. Adapters off the small coolant supply line to the throttle body can give you false readings. This is due to the fact that it is not in a constant coolant stream. The coolant in this line is controlled by the temp. controlled valve in the airbox, so since this valve can close and cut off flow when outside air temp reaches a certain level, that is obviously not an accurate reading. Plus air flows over the adapter, this can also change in the readings. This is not critical, but we like to have the best possible readings.

Doug
TMS

I don't know of anyone who keeps that valve in the line. Most people on here (not me...) don't even bother running the coolant hoses to the manifold, they just hook the spider hose to the cylinder head.

On the S52E30 I helped with, we plumbed the TB to the coolant hoses and put the adapter in the line. We've just now gotten around to ordering the proper sensor for it, so I can't tell you how it works yet.

[ian332isport]

have you added a resistor to the wiring adapter?

This is also not an option. You can put a resistor in parallel with the temp sender, but the value you choose would only be any good at a specific temperature. You could possibly use a thermistor in parallel with the existing sensor, but you are then back to the problem of where to mount it.

I have not made the necessary measurements yet, but you may be able to use another dual temp sender in place of the water fitting (throttle body heating), and use both sides of the dual temp sender in parallel (and possibly some extra resistors) to get it to read about right.

Ian.

[Jason89i]

i assume you are speaking of this adapter
http://www.turnermotorsport.com/html..._ID=TEN9989M50

[FONT=Arial]We have been using this adapter on our M52 / S52 conversion E30's and have had no issues with inaccurate readings. .........

Again, we have never had an inaccurate guage reading using our adapter when wired properly. We have done a number of conversions on E30's here and have sold dozens of these mail order, we have not had any problems with the readings to date.


Doug
TMS

doug -

what am i missing here? have you added a resistor to the wiring adapter? i assume the adapter is not just taking the gauge temp signal (2 of the 4 prongs) and sending it to the cluster (did not work for me.)

not trying to be argumentave, just trying to understand how you got it to work.

cheers, jason

[KangamangusDriver]

Ian,
Thanks for your insightful knowledge!

Very good to know!!

[ian332isport]

I guess I will be picking up a TMS adapter this spring when I get my car back.

You'll be wasting your money. Despite what Doug stated above, you will not get the double temp switch to drive a standard E30 temp gauge. It's resistance is completely wrong.

At around 10 or 12 degrees C (current ambient temperature in my garage). the temp gauge side of the dual temp switch (pins 1 & 2) measures approx 8.2K ohms, and the standard E30 gauge sender is around 900 ohms (single pin to sensor body). I don't have the measurements to hand, but the dual temp switch even when hot does not get as low as the E30 sender when cold (and therefore never reads on the gauge).

Ian.

[Funkmasta]

Most (all?) 96 S52s had a second port already tapped on the head from the factory, just comes with a plug.

[Bennetts22@aol.com]

Just tap the damn head. What is the big deal? Takes 5 min.

??? I might only take 3 min. but its done right and nothing is rigged up...

[equate975]

I dunno, everyone must have been doing this wrong or something. I knew it was a dual sensor like Doug said, it has 4 wires and is really 2 sensors in 1. But I didnt think the e30 guage could read either of those "2" sensors.

I think most of us followed the OBDI conversion guide by aceves

(link is dead of couse :( )

http://homepage.mac.com/aceves/OBDI/OBD_ONE1.htm

Atleast thats what I did, I even cross checked the wiring diagrams in the ETK and Bentley to make sure I had the right wires going to the right places. Best I could get the temp gauge to do was turn "on" but not get any reading.

Has anyone on r3v been able to make this sensor work? I guess I will be picking up a TMS adapter this spring when I get my car back.

[FredK]

Thanks for the info, Doug. I guess we can finally put the multiple temperature sensor threads to bed!

[dugmar]

Here is some information that may clear up some issues regarding the temperature sensor when running a 2.8 or 3.2 M52/S52 in an E30.

First, the reason we developed this part. Yes, you can drill and tap your cylinder head and add a second sensor. The only problem with that is that it is risky. If you do go that route make sure whoever is drilling is good. If they aren't, or if they do not set up the head on the mill, you could drill at the wrong angle, creating the wrong plane. This will result in a bad seal between the head surfrace and the sensor. This can lead to leaks or damage to the head.

Second, our mehtod compared to the manifold adapter option... We like to have our sensor in a constant coolant flow. Adapters off the small coolant supply line to the throttle body can give you false readings. This is due to the fact that it is not in a constant coolant stream. The coolant in this line is controlled by the temp. controlled valve in the airbox, so since this valve can close and cut off flow when outside air temp reaches a certain level, that is obviously not an accurate reading. Plus air flows over the adapter, this can also change in the readings. This is not critical, but we like to have the best possible readings.

Third, on the late model OBD-II temperature sensor... Technically, that is two separate sensors, with two different resistance levels, neatly packaged into one unit. If you look at that sensor you will see four prongs, two go to the ECU, two go to the cluster. Both are a different resistance and match the resistance levels of the two separate sensors that are in the earlier cars. We separate those two readings with our adapter, we don't go 1 to 2, we go from 2 to 2. The sensors read identical compared to the early sensors (As in the E30 and OBD-I E36) so if wired properly, this sensor should provide you accurate temp readings for both the instrument cluster and ECU on an E30.

We have been using this adapter on our M52 / S52 conversion E30's and have had no issues with inaccurate readings. We run wiring as follows: On the C101 plug, (the big round one next to the fuse box), pin 4 (brown with white tracer) should be connected to pin 12, on the x20 plug on the engine wiring harness.

Again, we have never had an inaccurate guage reading using our adapter when wired properly. We have done a number of conversions on E30's here and have sold dozens of these mail order, we have not had any problems with the readings to date.


Doug
TMS

[LINUS]

Sadly, I remember now what I knew before. You had to change that black 2 pole sender (e36) for a tan single pole temp sender (e30) to fire the cluster guage correctly for a OBD1 car, or ditch the OBD2 sender completely and get a e30 cluster sender and a e36 ecu sender.

Forgot that, so yeah, that coolant line splice seems like the only way to go if you for whatever reason won't tap the head.

[equate975]

http://www.turnermotorsport.com/html..._ID=TEN9989M50

I don't know anything about either method because I just tapped the head. If the other guys say it doesn't work, fine - I don't understand that since it's just a wiring adapter, but like I said - as long as you use a few step size bits and finish with the right size bit, tapping is easy and gives you factory fit and finish.

Good luck.

Yeah that does not work, the dual temp sensor on the stock OBDII s52 or m52 is one sensor that sends a signal to the ECU and the gauge in the cluster. When you do the OBDI conversion your harness is now setup to use 2 sensors instead of one. So, in an e36 OBDI swap that adapter would work, pretty much just tricking everything into thinking there are 2 sensors. Since an e36 obviously has an e36 cluster it can read the sensor still. If you just plug that into an e30 OBDI conversion, it will work still for the ECU but the e30 guage cannot read that sensor, it will just be "cold" all the time.

[LINUS]

Is this what you guys were talking about?

http://www.zionsvilleautosport.com/store/shop.mv?Screen=PROD&Store_Code=6134&Product_Code=OBDITSM&Category_Code=CKE

That's one of the Zionsville ways I was talking about. Turner and Zionsville do this too, just don't know where it is on Zion's site - Dwight just said they had it too, but it didn't matter for me since I just made the hole:

http://www.turnermotorsport.com/html..._ID=TEN9989M50

I don't know anything about either method because I just tapped the head. If the other guys say it doesn't work, fine - I don't understand that since it's just a wiring adapter, but like I said - as long as you use a few step size bits and finish with the right size bit, tapping is easy and gives you factory fit and finish.

Good luck.

[equate975]

Also a bit OT here, and just so I can post whore this with another post lol

http://www.turnermotorsport.com/html..._ID=TEN9931007

Thats pretty much worthless too. You can take the stock OBDII metal pipe and just cut it and do the same thing. Thats what I did and I have no issues with it.

[equate975]

I guess that makes it a pretty worthless piece of wiring then

http://www.turnermotorsport.com/html..._ID=TEN9989M50

That would only be used if you are doing an OBDI conversion in an e36.

I just cut up my harness to make one, only to find out later it didnt work. Should researched better lol.

For an e30 OBDI conversion all you really need to do is plug the 1 harness in for the s52 sensor, then plug the other one into your e30 gauge sensor.