M52 in an 86 325 swap & tach doesn't work?

[tn325i]

Title says it. Everything else is working perfectly. I have read this both ways for my year car. One says you need a different coding plug for the tach to work. Another says you don't need to change anything. Looking for which coding plug I need or what to do.

on another note,
I love the way the car feels with this engine in it. Has a very natural feel to it. I never imagined it would be that different. I have had the swap stuff for a while it was intended for a different car. But the ol' M20 was giving me troubles which led to it going in this car.

[jeffmn8]

Did you check the wiring? Did you use an adapter or convert the harness?

[LTDScott]

Did you hook up the tach wire from the C104 on the passenger side of the dash?

[joecassie]

yeah its the black wire and how did you hook up your temp gauge i cant figure out mine

[ForcedFirebird]

Did you hook up the tach wire from the C104 on the passenger side of the dash?

Yup.

In 86 there's a small clear/whitish plug with 3 wires, yellow, green and black. The black wire goes to the tach. It wasn't until later years the tach signal went through the round c101.

[eurosport22]

you only need a coding plug in the equation if you changed the tach itself.

[evandael]

the coding plug shouldn't need to change, the 325 is already a 6 cylinder car.

as mentioned previously, pin 1 and 3 on the c104 are for RPM and MPG, respectively. run jumper wires from there to the c101 or your adapter to mate up with the e36 engine harness.

wiring for the temp gauge should come from the e36 harness to the e30 cluster through pins x20p12 and c101p4 (may be different on your setup), use a brown top single pin M20 coolant sensor in the M52 block (which may need to be drilled and tapped, i'm not sure)

[joecassie]

yes you have to change the coding pulg

[tn325i]

yes you have to change the coding pulg

I have triple checked wiring. Don't see anything out of place.






Can you give me a part number for the plug ?


Thanks

[joecassie]

idk what it is just make sure its out of a 325i trust me i have the same year car but a s50 in mine

[tn325i]

Cool Thanks. Will give it a try when I get in tonight. I have a plug from another car that was an I car.


Found a part # on realoem = 1385468 is an I plug.

[ForcedFirebird]

you only need a coding plug in the equation if you changed the tach itself.

the coding plug shouldn't need to change, the 325 is already a 6 cylinder car.

as mentioned previously, pin 1 and 3 on the c104 are for RPM and MPG, respectively. run jumper wires from there to the c101 or your adapter to mate up with the e36 engine harness.

wiring for the temp gauge should come from the e36 harness to the e30 cluster through pins x20p12 and c101p4 (may be different on your setup), use a brown top single pin M20 coolant sensor in the M52 block (which may need to be drilled and tapped, i'm not sure)

yes you have to change the coding pulg

I have done several swaps and as long as the cluster is from a 6 cyl car, then the plug DOES NOT need to be changed. If the car was a 318 originally, then the plug needs to change.

Really tired of wrong info being given out.

[nando]

won't he be stuck with a 5k tach though?

[ForcedFirebird]

won't he be stuck with a 5k tach though?

No. He will need to use an early VDO or MotoMeter tach and plug it in the cluster. The early and late VDO and MotorMeter are interchangeable, but not early to late.

The 86 cluster when pulled apart will have the econogauge separate from the tach, the late style the econo/tach comes out as one unit. As long as he uses an 87 or earlier tach, it's plug and play. Just went through this on my car, and having a stack of late clusters was of no help. I wanted to keep my original cluster (mileage).

Then there's two of each cluster (late and early) to make things more confusing. Some clusters have an additional "green box" attached to the back that accepts a wire that has no place to go on the clusters without the "green box". Some clusters have a spot for this junction to plug in, some don't. The m3 cluster has the green junction for the oil temp, not sure what it is on the other cars (never traced it), but the cluster won't work proper without that wire connected.

Simplest thing to do IMHO is to just use an early 7k tach and plug it into the 86 cluster.

[tn325i]

I'm not trying to create any debate. My biggest problem is the confusion of one says this and another says that. I am trying to pick out what will work for my car. All of them (each year) have their little differences.

I appreciate each and every response. I realize any item in the line of things that make these work can ruin the whole attempt. So all have input but likely only one combo will work in my particular car. I have to try some of the suggestions until things begin to move.

Again, Thanks to all !