DrewJetta
Member
Hi guys - need a little help here. I've searched everywhere and found some leads but all dead ends. Here is the situation:
2004 BEW Jetta Wagon. 274,000 miles - all original engine components. Meticulously maintained by the book. Mobile 1 TDT since 80K Miles. All 505.01 before then. Changed every 10K miles.
About 3 months ago I got a MAF code - implausible signal P0101. Replaced MAF - this is my third and know they do go bad - had this one in the car of about 10 years. Error comes back with new MAF. intermittent error code. comes and goes. engine runs fine. fuel consumption is fine. I disassemble and clean EGR - it was gunked up but not that bad. MAF error light is now off - may come back.
At about the same time my engine started to have an inconsistent idle which MOSTLY occurs when the engine is dead cold. Runs fine otherwise and rarely occurs when warm. Engine will decrease idle by a bit and then blip over 900rpm and settle back down. Does this cyclically/irregular about once per second. It is very noticeable. Does it most of the time when cold. It has done it a bit when warm though much less likely.
There was no change/maintenance the coincides with this behavior. Just started one day. This behavior didn't grow into this problem. One day it just started.
Here is what I did - Checked Rosstech VagCom - did notice idle adaptation was significantly off (Per other threads I read) when this was occurring for cylinder 1 and 3. When the engine was idling smooth, there was still a bit of adaptation on 1&3 but it was what I would consider normal for an engine of this vintage. don't remember the exact values but they more closely matched across all four cylinders.
Checked the full intake for any air leaks/faulty connections - didn't find any. Engine air filter is newer (3000 miles on it) but I do see some oil weeping around the connections leading to the intercooler and to the turbo. This is the original turbo.
Checked for any vacuum line leaks - no sign of any.
Checked coolant temps with VagCom - all were in spec and reading correctly.
No engine ticking/knocking but still have to remove the valve cover to check cam lobes - still original cam and injectors.
Theories: Considering this mostly happens when cold could this be:
1. turbo failure - oil leaking around bearings into intake - only takes a few drops here and there to get consumed by engine. at higher RPMS the turbo seals up under load and as it warms up tolerances close off the leak?
2. Vacuum leak due to a connection that gets tighter when warm? Could this be intake plumbing issue as there is a coinciding MAF error code that intermittently pops up.
3. Cam is failing and may need to be replaced? But if this is the case what would things change with engine temp and wouldn't this grow over time instead of all at once?
I love this little car - she's been good to me and owes me nothing but I need her to last me one more year and I'd love to join the 300K mile club. Any insights and guidance you guys can provide will help. I'll post pics of the cam and VAGCom readings tomorrow. I hate these intermittent issues!
2004 BEW Jetta Wagon. 274,000 miles - all original engine components. Meticulously maintained by the book. Mobile 1 TDT since 80K Miles. All 505.01 before then. Changed every 10K miles.
About 3 months ago I got a MAF code - implausible signal P0101. Replaced MAF - this is my third and know they do go bad - had this one in the car of about 10 years. Error comes back with new MAF. intermittent error code. comes and goes. engine runs fine. fuel consumption is fine. I disassemble and clean EGR - it was gunked up but not that bad. MAF error light is now off - may come back.
At about the same time my engine started to have an inconsistent idle which MOSTLY occurs when the engine is dead cold. Runs fine otherwise and rarely occurs when warm. Engine will decrease idle by a bit and then blip over 900rpm and settle back down. Does this cyclically/irregular about once per second. It is very noticeable. Does it most of the time when cold. It has done it a bit when warm though much less likely.
There was no change/maintenance the coincides with this behavior. Just started one day. This behavior didn't grow into this problem. One day it just started.
Here is what I did - Checked Rosstech VagCom - did notice idle adaptation was significantly off (Per other threads I read) when this was occurring for cylinder 1 and 3. When the engine was idling smooth, there was still a bit of adaptation on 1&3 but it was what I would consider normal for an engine of this vintage. don't remember the exact values but they more closely matched across all four cylinders.
Checked the full intake for any air leaks/faulty connections - didn't find any. Engine air filter is newer (3000 miles on it) but I do see some oil weeping around the connections leading to the intercooler and to the turbo. This is the original turbo.
Checked for any vacuum line leaks - no sign of any.
Checked coolant temps with VagCom - all were in spec and reading correctly.
No engine ticking/knocking but still have to remove the valve cover to check cam lobes - still original cam and injectors.
Theories: Considering this mostly happens when cold could this be:
1. turbo failure - oil leaking around bearings into intake - only takes a few drops here and there to get consumed by engine. at higher RPMS the turbo seals up under load and as it warms up tolerances close off the leak?
2. Vacuum leak due to a connection that gets tighter when warm? Could this be intake plumbing issue as there is a coinciding MAF error code that intermittently pops up.
3. Cam is failing and may need to be replaced? But if this is the case what would things change with engine temp and wouldn't this grow over time instead of all at once?
I love this little car - she's been good to me and owes me nothing but I need her to last me one more year and I'd love to join the 300K mile club. Any insights and guidance you guys can provide will help. I'll post pics of the cam and VAGCom readings tomorrow. I hate these intermittent issues!
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