I have had it all with this 86 Jetta. It is very similar for years 85 through 92. The computer will exaggerate "idle fluctuation" whenever there really is some type of problem. Basically, a minor tune up will fix it: Clean the air flow sensor with cleaner, check timing and then replace plugs. That usually does it in that order. Every three times of that then cleaner should be put in the manifold area of small air lines, even the idle mix screw gets dirty. But injectors rarely get messed up, don't need fuel injector cleaner.
Other "idle fluctuation" problems are caused by: Loose ground wire on top of block. Fuel filter and or pumps going out. Fuel mixture too lean or too rich in the air flow sensor location could also cause fluctuation and stalling. Also, when the Bosch fuel filter clogs at about nearly 200K miles your fuel pumps get worked and the relay #65 melts the soldering. You should replace the large filter every 150K. High speed is the test for electric fuel pumps. Taking apart the relay and pluggin it back in enables you to press on the magneto switch to listen to the pumps or drain the fuel faster. Since the manifold rubber boot is inbetween the engine and the air filter mounted to the sidewall a leak in the rubber boot will exaggerate jerky acceleration deceleration problems. Usaualy, in first gear with the most torque. A wide open leak on the boot will easily otherwise stall the idling engine. Use quick start to find leaks but man handle the rubber to exaggerate leaks too.
11-12-2003, 04:35 AM
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