The first post about Jeff’s E34 left us with a mildly improved, but still rough, engine and idle. The door pull cable was still in shambles and both windows on the driver’s side didn’t work. Thankfully, we have made some progress.
In driving the car around town, I noticed the idle getting progressively lumpier. Acceleration was taking a similar hit – the car felt like VTEC was kicking in and was surging badly. Yes, the M50 motor in the car does have Vanos (BMW’s term for variable valve timing) but the variances should not be noticeable to the driver. This was significant.
As I surfed forums and tried to come up with reasons why the car could be stumbling so badly, I was presented with a pretty impressive list of possibilities. Vacuum leak, bad O2 sensor, fuel filter, ignition coils, Vanos unit, etc. Some of the repairs would be cheap and others, not so much. I took a gamble when I ordered the power window regulators and picked up a new OEM fuel filter for $10. My thinking was that it would be good to replace regardless, and it can only help the car’s performance long-term.
Mentally, I was reviewing the first big wrench day on the car. Cabell put the ignition coils back on the motor, but I did notice something potentially amiss. I thought I remembered one of the coils looking somewhat… melted. Now, coils are not cheap. There is one for each cylinder, so we would need six. Pelican Parts – about the cheapest BMW parts supplier online – has them for $48.25 each. As I said, not cheap.
I struck gold with Rex, an MM alumni who lives in Northern Virginia. He had a set of six known-good coils, from a 1995 E34, that he would sell me for $50 total. Conveniently, I would be up in NoVA the next weekend and could pick them up. Done deal, I told him.
Today’s weather was (according to my iPhone) 45° and sunny. In reality, it was about 35° and windy with a hint of snow. I asserted my stubbornness against Mother Nature and installed the new coils anyway. After my 20 minute project, the Bimmer started right up. I pulled onto Main Street and gave it some gas. The surging was gone. The bad idle was gone. The motor is still good, after 195,000 miles. It pulls like a BMW Inline-6 should.
We’ll still be installing the new fuel filter, since I have the part. Between that, and fixing the power windows, I’d say we have our hands slightly full. We also need to re-connect the driver’s door lock mechanism. The key will only unlock the car from the passenger door. It’ll be a quick fix while we do the windows.
Hooray, progress!
Tags: 525iA, BMW, E34, Madison Motorsports