1992 325i convertible
Guys,
Having a problem with a "lopey" idle after a timing belt change. Did a lot of research on this forum and got some good information, but no cure.
My local indy shop made the change, then the car was stored and later shipped to Florida. I haven't driven too many miles, but noticed a rough idle. This is new...it ran fine before the change. I've checked everything that could cause the problem (vacuum leaks, compression, valve adjustment, temp sensor, O2 sensor) and replaced ignition wires, spark plugs, cap, rotor, throttle position switch - which was bad, intake air "boot" and injectors) but to no avail. The car runs fine under load, but at idle it sounds like it has a cam or a weak cylinder. At 600 rpm idle the frequency of the "miss" is about 300 beats per minute...so I thought it was a weak cylinder or a bad injector. Compression checks out ok and new injectore were installed.
But, because the problem persists, I'm starting to suspect the workmanship of my local indy shop. Could they have installed the new timing belt off by a tooth or two? Some threads alude to similar problems. Now, I'm trying to figure out how far I have to tear into the engine to confirm the "timing" of the belt. So far, I think I have to pull the hood, fan clutch, radiator, hoses in front of the upper belt cover, cap , rotor and upper belt cover to expose the cam gear. Then, set the crank pulley to TDC and check the timing mark on the cam gear. Or, can I get enough precision of the cam rotation location from the ignition rotor? Are there any timing marks on the upper belt cover or rotor dust cover to indicate the rotor position at TDC?
By my calculations, one tooth off is about 7.5 degrees which could easily cause idle problems, but not necessarily driveability problems. Can the rotor position give me enough accuracy?
What are your thoughts?
Guys,
Having a problem with a "lopey" idle after a timing belt change. Did a lot of research on this forum and got some good information, but no cure.
My local indy shop made the change, then the car was stored and later shipped to Florida. I haven't driven too many miles, but noticed a rough idle. This is new...it ran fine before the change. I've checked everything that could cause the problem (vacuum leaks, compression, valve adjustment, temp sensor, O2 sensor) and replaced ignition wires, spark plugs, cap, rotor, throttle position switch - which was bad, intake air "boot" and injectors) but to no avail. The car runs fine under load, but at idle it sounds like it has a cam or a weak cylinder. At 600 rpm idle the frequency of the "miss" is about 300 beats per minute...so I thought it was a weak cylinder or a bad injector. Compression checks out ok and new injectore were installed.
But, because the problem persists, I'm starting to suspect the workmanship of my local indy shop. Could they have installed the new timing belt off by a tooth or two? Some threads alude to similar problems. Now, I'm trying to figure out how far I have to tear into the engine to confirm the "timing" of the belt. So far, I think I have to pull the hood, fan clutch, radiator, hoses in front of the upper belt cover, cap , rotor and upper belt cover to expose the cam gear. Then, set the crank pulley to TDC and check the timing mark on the cam gear. Or, can I get enough precision of the cam rotation location from the ignition rotor? Are there any timing marks on the upper belt cover or rotor dust cover to indicate the rotor position at TDC?
By my calculations, one tooth off is about 7.5 degrees which could easily cause idle problems, but not necessarily driveability problems. Can the rotor position give me enough accuracy?
What are your thoughts?
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