Diagnostic assistance needed.
Vehicle:
1999 VW Jetta, Base Model, 5-speed, 2.0L w/electronic throttle control
Symptoms:
Lack of power, violent surging under load. Does not exhibit any
symptoms during no-load revving. Problem is intermittent--usually
there, but goes away on occasion.
DTCs: P0300, P0302, P0303. Codes re-occur if cleared.
Diagnosis to date:
1. Weak spark cyls 2 & 3. Coil/module assembly replaced.
2. Fuel Pressure OK. 35-45psi while driving. Holds steady (does not
dip) when problem is duplicated.
3. Fuel injector flow-balance ok. All 4 injectors drop 10psi (from
39psi to 29psi) when pulsed 100 times (5ms each) using OTC injector
timer.
4. Engine mechanically sound. Compression & leak-down ok.
5. Mass airflow meter and intake air hose integrity verified.
Suspect wiring problem--intermittent open/short. Scan tool data
reveals nothing toward that end.
Anyone experience this before?
-Dave
Glendora, CA
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