2.7i questions

[Chriskbmx]

first question is, is there a difference between the e30 m20 harness and the e34 m20 harness? I pulled the full top end from and e34 and took the harness. If the e34 harness is different what is going to be needed to make it work?

Also what sensors are 1.1/1.3 motronic specific?

this is going into a 1987 325e.

I ripped the 885 head down and plan on checking that its flat, and possibly getting it decked. Any use for a bigger cam? or is the compression to low to make use of a cam any bigger than the I cam?

Also, what all is needed to convert to the late model cooling system?

Do I need the I starter to work with the harness.

I know some of this is been covered but, the thread on it is filled with a bunch of junk comments, I get lost lol.

Thanks!
chris.

[MR 325]

Although I don't know the exact differences I can say that the E34 harness is indeed different. I'd recommend getting the correct E30 harness instead of trying to make the E34 harness work. All M20B25 engines use the same sensors except for the o2 which is different between 1.1 and 1.3.

Anytime a head is being installed it should first be resurfaced. Even a head from a perfectly running engine that never overheated can be slightly warped. Do it once and do it right. If you want a cam I would recommend a 272 or 274 cam for that combo but nothing more. I've done a 2.7i (Eta bottom end 885 top end) with a friend and with a 274 cam and port/polish head it pulled very hard.

To run a late model cooling system you simply install the 88+ parts. All hoses, water pump, radiator, and expansion tank. I've done this to almost every early model car I've owned. I prefer the late model system myself.

[Chriskbmx]

any idea what a basic resurface should cost? I was worried about useing a cam because of the super low compression ration, but how much can i take off the head to try and raise the compression ratio?

what is the extent of your port and polish?

[Regnar75]

my 2.7i

I'm also not too sure on the differences in harnesses but the late model cooling you need the coolant expansion tank hoses and radiator. (E36 radiator should work) the starter should match your flywheel. I am using the early model starter (86es) with the motronic 1.3 harness. Just had to wire things up a bit. If your using an early model and need to wire up the o2 sensor check out my post in the last page of the 2.7i thread. Same with starter. I'm not running a cam and I still love how quick it is

[Chriskbmx]

this is gonna be a budget play car, so 7000rpm chip, 274 cam, heavy duty rockers, and 4.10. shall be fun.

[Swanny]

You'll need an 87 i harness for total plug and play to keep all your gauges working. As mentioned before if you have a dual mass flywheel then keep the starter from the e, if switching to the lighter I flywheel (which needs more to it than just that to keep the spacing correct in your ETA) then use an i starter. You'll have some left over sensors from your bell housing after the conversion so don,t be freaked out when you have some connectors not plugged in under the "bitch tube" when you're all done.

Why exactly are you switching over to late model cooling? No real advantages unless all your current cooling equipment is toast and you need to start fresh anyway. Just remember that the late models have a different water pump.

[Regnar75]

You'll need an 87 i harness for total plug and play to keep all your gauges working. As mentioned before if you have a dual mass flywheel then keep the starter from the e, if switching to the lighter I flywheel (which needs more to it than just that to keep the spacing correct in your ETA) then use an i starter. You'll have some left over sensors from your bell housing after the conversion so don,t be freaked out when you have some connectors not plugged in under the "bitch tube" when you're all done.

Why exactly are you switching over to late model cooling? No real advantages unless all your current cooling equipment is toast and you need to start fresh anyway. Just remember that the late models have a different water pump.

Good point on the water pump. I kept the early model cooling and don't have any issues. Early starter and o2 sensor with no issues. I still have the 2.93lsd though which I'm going to use a 4.10lsd if I find one. It is kinda fun hitting 70mph in 2nd gear. Also a 2.7i chip from eurotuning

[Chriskbmx]

i am not new to cars, i know exactly how this swap works, just asking for comfromation. i can use any harness and run speed signal. anyone know how to do that?

also im going to use the i flywheel and clutch i have. i will use a euro 323i bearing. ill just remove the referance sensors and make a delte plate.

[Regnar75]

Wish I could help you I know nothing about the 5series harness. The speedo is run (on early model) through c104(I think) in the glove box but on later models goes through the connection by the fuse box. I used an early I harness so speedo hooked right up. The tach and eco gauge needs to be wired through the glove box. I'm just going to stop talking now. Your using a 5 series harness all of this could be irrelevant to you.

[Chriskbmx]

im going to use an e30 harness, so if anyone has an early for sale, or wants to trade or obd1 m50 manifold and throttle body lmk.

so where do i have to wire the c104 into?

[ForcedFirebird]

The starters are the same, just the small wire attachment type is different.

To run late model coolant system, MR 325 is right. You will need all associated cooling parts from a late model, but if your cooling system is in good working order, it's not required to change for the swap since the "i" was offered in 87 and used the early system.

As far as sensors, you will need crank position, AFM, coolant temp (blue one), crank sensor, and best to have the #6 spark plug wire sensor (car will run without it, though).

Also, the eta got a different water pump pulley to match the diameter of the crank hub. If you don't want to spend time testing belts, just use the correct pump pulley to use a stock length belt.

The tach and economy gauge will have to be hooked up in the glove box, near the ECU connector. The fire wall pass through where the harness goes will have to be opened up slightly.

You may need some vacuum lines for the brake booster, crank breather hose and evap canister hose/solenoid.

Check out strictlyeta.net, the swap is well outlined there.

[Chriskbmx]

i have all of that stuff lol. the only reason i wanted to go to a late model cooling system was because i need all new belts, timing belt, water pump, and all the hoses are old so figured i would just do it up all at once.