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When an E30 won’t start I have an intermittent no-start condition on one of my 1989 325i cars. When it starts, it starts without hesitation and idles fine. About once or twice a week, however, it will not start. After much cranking with no success, if you let it sit about ten minutes and try again it usually will come to life reluctantly, and it usually requires some finesse on the gas pedal. The last time I had starting problems, I tested the ignition coil and crank position sensor using the procedures in the Bentley manual and they checked out okay. What else do I need to test? The car has 216,000 miles, the intake boot is about one year old, the cap and rotor are new and I’ve cleaned the intake manifold and idle control valve with carburetor cleaner. I have had slight idle problems that would sometimes stall out the engine on rare occasions; based on your recommendation, the ICV is on the menu for replacement. I haven’t done it yet because the idle problems are very rare. Could the ICV be causing these no-start conditions? Also, in the E30 Buyers Guide in Bimmer #44, you mentioned using E30 M3 control arm bushings. I’m content with the factory suspension with a Bilstein HD shock upgrade. Would I still benefit from these bushings, or does this only apply to track or highly-tuned suspensions? I’m always interested in replacing worn out parts with better ones. Scott Steele Andover, KS Here’s what you need to do to address your no-start problem: 1. You know you need a new idle control valve. Replace it now to take it out of the no-start diagnostic equation. 2. Assuming the no-start condition persists after idle control valve replacement, while the no-start condition is occurring, check for ignition spark and power out of the fuel pump relay. It is probably a no-fuel condition. 3. If there is no power out of the fuel pump relay, check for power out of the main relay. 4. If there is no power from the main relay, check for power into the main relay. 5. The main relay controls all digital Motronic functions including supplying the fuel pump relay. If you have power out of the main relay and into the fuel pump relay but not out of the fuel pump relay, replace the fuel pump relay. 6. If you have power out of the fuel pump relay, verify power at the fuel pump. If there is power at the fuel pump and no function, replace the fuel pump and fuel filter. If there is fuel pump function and no start, verify fuel pump delivery rate and fuel pressure at the pump and the engine per the Bentley manual. 7. If there is power into the main relay but not out of the main relay, replace the main relay. 8. If there is no power at the main relay, access the on-board computer control module and wiggle it while turning the key to the start position. Sometimes solder joints fail inside the OBC control module, which can cut power to the main relay. Remember that the OBC has a programmable anti-theft function; it works by cutting power to the main relay. Procedures for programming the OBC anti-theft function are located in the owner’s manual. If the problem is the OBC control module and you have electronics repair skills and equipment, you can open the unit and flow fresh solder over all the joints. Otherwise, it’s time for a new OBC control module from BMW. 9. If there is no power at the main relay and the OBC control module is not at fault, then you have a faulty digital Motronic electronic control unit—the main computer. I recommend preventative fuel pump, fuel pump relay and main relay replacement every 120,000 miles to guard against a no-start breakdown. The E30 M3 front control arm bushings are offset compared to the regular E30 front control arm bushings. The offset provides added positive caster for greatly enhanced high-speed stability. The E30 M3 front control arm bushings are also solid rubber, making them a great deal stronger than the regular E30 front control arm bushings. However, I have never installed the E30 M3 front control arm bushings on a non-M3 E30 equipped with stock coil springs. I do not know what effect the high ride height would have on the whole equation. | |
