We've got a 2000 Beetle 1.8T that won't quite rev to 2000 when cold , or 3000 when warm. These limits are consistent, with very little power. This thread is for good old trouble-shooting without the help of scans. We can't scan it for unknown reason(s), but never could scan this car.
Background:
-The car ran great last winter, and was running well when parked in March. It probably has a tune of unknown origin. The check engine light was always on.
-It sat outdoors for 8 months, and then intermittently started acting up (not revving over 2K when cold or 3K when warm), but finally worked well in Nov/Dec after cycling the ignition a few times.
-Then after sitting until Jan, cycling the ignition no longer helped anymore.
Testing:
-Replaced battery with a brand new one.
-Car starts on a dime and generally idles acceptably when cold (very slightly rough, but with 2K rpm max at WOT), and fully smooths out once warm (but with 3K rpm max at WOT). These rpm limits were consistent after many tries.
-Warm or cold, it's way down on both rpms and power (slowed to under 20 mph up hills on the test drive).
-A vacuum gauge (actually the low resolution negative section of a combo boost/vac guage) reads steady negative teens range at idle, but unsure of units (psi or in-Hg, etc).
-Tried cleaning the MAF (especially since it's behind a cheapo aftermarket cone filter), but no difference. Disconnecting the MAF completely was also no better.
-Cleaned out light gray crank sensor connector with brake clean and compressed air in case of moisture ingress (potentially from melting snow), and water-proofed with dielectric grease, but again no difference.
Next:
So far our to-try-next list includes checking ECU grounds, and replacing coolant sensor, but time's running out.
Question:
Assuming it's not practical to extract codes (working on that separately but doesn't look promising), any idea what might be causing this particular loss of revs and power?
Background:
-The car ran great last winter, and was running well when parked in March. It probably has a tune of unknown origin. The check engine light was always on.
-It sat outdoors for 8 months, and then intermittently started acting up (not revving over 2K when cold or 3K when warm), but finally worked well in Nov/Dec after cycling the ignition a few times.
-Then after sitting until Jan, cycling the ignition no longer helped anymore.
Testing:
-Replaced battery with a brand new one.
-Car starts on a dime and generally idles acceptably when cold (very slightly rough, but with 2K rpm max at WOT), and fully smooths out once warm (but with 3K rpm max at WOT). These rpm limits were consistent after many tries.
-Warm or cold, it's way down on both rpms and power (slowed to under 20 mph up hills on the test drive).
-A vacuum gauge (actually the low resolution negative section of a combo boost/vac guage) reads steady negative teens range at idle, but unsure of units (psi or in-Hg, etc).
-Tried cleaning the MAF (especially since it's behind a cheapo aftermarket cone filter), but no difference. Disconnecting the MAF completely was also no better.
-Cleaned out light gray crank sensor connector with brake clean and compressed air in case of moisture ingress (potentially from melting snow), and water-proofed with dielectric grease, but again no difference.
Next:
So far our to-try-next list includes checking ECU grounds, and replacing coolant sensor, but time's running out.
Question:
Assuming it's not practical to extract codes (working on that separately but doesn't look promising), any idea what might be causing this particular loss of revs and power?
