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Discussion Starter · #1 ·
Feel like I've lost a good bit of power, perhaps over time but caR just doesn't feel like it ought to. Experiencing the following symptoms for the last couple years really but finally annoying me into a serious investigation:

The car seems like it wants to stall (RPM dips below 700 and caR shudders) occasionally at idle, particularly in stop-and-go traffic when RPM return to idle after revving and moving forward. Seems to dip below "normal" level of around 750, caR shudders, then it returns to a normal idle. But sometimes at extended idle, this condition seems to switch on and off periodically without any throttle application.

During hard acceleration the engine will seem to stutter just a bit as boost builds. This seems to happen less when the caR is hot after a 15-20 minute drive.

I do have a boost gauge installed and consistently see peak 15 psi that gradually tapers off through a pull in any given gear.

I have a PhMIC, 3" DP, 3" exhaust, ipd HD coils, K&N filter with R Kelly CAI, Snabb turbo intake pipe, and recently installed Phuz (MAC) TCV and have all silicone tcv hoses. MAF is still original (95k miles) but cleaned about 20k ago. Replaced entire PCV system 6k ago. Fuel press sensor replaced about 20k ago. Spark plugs are about 35k old. That's all I can think of. Any suggestions on how to proceed? TIA
 

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Check your throttle body to see if it needs cleaning?
 

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Get VIDA/DICE and scan for codes...
 

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This is my first post, I mostly just browse but I have recently had this entire exact experience to the parts being installed, cleaned etc. When my indy performed my PCV replace it mostly started after that. I also installed the Phuzzy TCV a week later. Does anyone know if when the PCV was replaced if maybe the Mini Breather filter (if is even stock on the R) was replaced with it? I also just recently used seafoam and felt a change for about a week then after some hard driving it returned. It is starting to drive me insane as well!
 

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This is my first post, I mostly just browse but I have recently had this entire exact experience to the parts being installed, cleaned etc. When my indy performed my PCV replace it mostly started after that. I also installed the Phuzzy TCV a week later. Does anyone know if when the PCV was replaced if maybe the Mini Breather filter (if is even stock on the R) was replaced with it? I also just recently used seafoam and felt a change for about a week then after some hard driving it returned. It is starting to drive me insane as well!
I would be careful with seafoam... I lost my s40s cat by seafoaming it and I have 4 friends that their cats went after seafoam. So I would try to stay away from the stuff if I were you.
 

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how many miles? time for new plugs maybe
 

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in all honesty...

swap back in your stock TCV and report back on the drive-ability :)

cool?


as for the idle stumbles, mine does that occasioanlly. but not enough to warrant me ripping the car apart to find a mystery item :)
 

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This could be a leak in the air intake system, the one who gets replaces by the "SNABB intake" , is prone to failure as it made in plastic and is in a harsh environnement ( Vibration, close to brake pipes, etc) Look for the pipe you can see near the rad support, who conncets to the I/C, They could be leaky... I've just seen a serious idling problem on a 850 caused by a crack in that pipe...
 

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Discussion Starter · #9 ·
Original post

how many miles? time for new plugs maybe
Resolved mostly. Replaced plugs with new stock ones, realized it had been about 50k. Restored consistent power and I feel very happy again. Still have the fluctuating, low-RPM idle but it is not hurting anything and doesn't stall - it's just a little curious...
 

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Just did the same! I replaced the fuel filter and OEM spark plugs ($$$$) and consistent power is back. It is sad because I feel as though I should have done this when I drove it off the lot back in May. The difference is disgusting! I have a pic from the old and new i should post as well. The idle stutter is still there and a little bit of "stalling feeling", but otherwise I'm very happy with the outcome. I'm wondering if i need to replaced the engine mounts in the front and back. I had a broken upper engine mount for about 4 months and the extra play probably broke the hydraulics in the mounts. Just went over 100,000 so it would make sense.
 

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Just did the same! I replaced the fuel filter and OEM spark plugs ($$$$) and consistent power is back. It is sad because I feel as though I should have done this when I drove it off the lot back in May. The difference is disgusting! I have a pic from the old and new i should post as well. The idle stutter is still there and a little bit of "stalling feeling", but otherwise I'm very happy with the outcome. I'm wondering if i need to replaced the engine mounts in the front and back. I had a broken upper engine mount for about 4 months and the extra play probably broke the hydraulics in the mounts. Just went over 100,000 so it would make sense.
I'm thinkin the same with my mounts, I wonder if those can be removed easily?
 
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