I dropped a 98 S52 motor and trans into my 1994 318is. I converted the motor to OBD1 and replaced all the necesary parts to get it to run. I'm also using a TMS chip, 24lb injectors, 3.5" HFM and cold air intake with a 3:23 LSD rear. Runs awesome and really happy with the swap.

Few questions though.

1). If I let it idle for a couple minutes, the check engine light will come on and idle will become really rough. Light will turn off if I rev it up high enough. I was thinking throttle positioning sensor?

2). No heat. I'm using a new M3 radiator and never had the motor overheat. Coolant levels are always where they should be but will not put out any heat inside the car. I think all the lines are hooked up to the heater core correctly? Is there something on the 318 heater core that needs to be changed?

3). Tachometer reads about double what it should be. Pretty cool because it will wrap around to about 0 rpm before the rev limiter kicks in. Is there something I can change in the 318 cluster or should I just go out and buy an M3 one?

Any input on either question will be helpful. Until then, I'll keep it reving with a coat on shifting at about 40 on the MPG gauge getting sideways around town.

Thanks,

1. Check the TPS and then clean the idle air bypass?

2. There's a valve that controls the flow to the car's 2 stage heater core. It should be a 3 wire connector. Make sure it is connected?

3. The car's tach is looking for a 4 cylinder input, but you are sending a 6 cylinder output. There's places that can make a "black box" to change the signal frequency for this type of conversion...

Dakota Digital: http://www.dakotadigital.com/index.cfm/page/ptype=results/Category_ID=287/home_id=59/mode=cat/cat287.htm

Just get a m3 cluster, i had the opposite problem when i had the m3 cluster on my 318.

Just make sure to get a cluster from a 95 M3. I believe the 96 and up clusters have different circuitry or something. You've performed my dream swap. Cool man!

you should also be able to use a 325i cluster.

Thanks for the info guys. This forum would have been helpful when I was doing the swap. Kinda did what seemed right and bits of info from here and there. Still trying to sell parts from it. No one seems to want OBDII parts.

I like your idea of looking at the simple solutions first. Just bought a house so don't have much money to dump into the car. I'll try cleaning out the TPS. The idle air bypass looked clean when I put it in.

If I can get back there, I'll check the connection to the heater core and make sure its getting the correct voltage.

I figured the cluster is reading the 4cyl tach when it should be now reading 6. I've heard of some clusters having a switch in the back to change cylinders but dont thing BMW's do that. I like the look of the M3 cluster as everyone mentioned although the black box sounded like a cool option to keep the stock cluster with the correct milage.