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Changed the FPS this weekend and took it for a drive. Throttle response much better so the old part did need to go. But, full throttle acceleration still has pulsation and coasting still brings the occasional bucking or sometimes feels like loss of power that comes right back with a touch of the accelerator.

What next? :confused:

- Fuel filter? I know there's one in the tank, is there also an in-line by right rear wheel?
- O2 sensor or MAF? (Running a K&N, nothing high performance)
- Turbo related?
- Throttle sensor?

Bought new 7 years ago, now 78K mi, never any issues with the powerplant or trans excepti the PCV being changed out at 68K mi. Taken great care with oils/maintenance.

Any help or suggestions greatly appreciated!

Drew
 

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Changed the FPS this weekend and took it for a drive. Throttle response much better so the old part did need to go. But, full throttle acceleration still has pulsation and coasting still brings the occasional bucking or sometimes feels like loss of power that comes right back with a touch of the accelerator.

What next? :confused:

- Fuel filter? I know there's one in the tank, is there also an in-line by right rear wheel?
- O2 sensor or MAF? (Running a K&N, nothing high performance)
- Turbo related?
- Throttle sensor?

Bought new 7 years ago, now 78K mi, never any issues with the powerplant or trans excepti the PCV being changed out at 68K mi. Taken great care with oils/maintenance.

Any help or suggestions greatly appreciated!

Drew
Hey Drew
Ive got a 09 C30 T5 with pretty heavy modifications, all Stage III and Im having the exact same issue at this point in time. Replaced the axles out of necessity, the PCV at 81 and Im still having the throttle breaking up in 4th gear only. I have the auto and dont seem to notice the issue in any gear other than fourth also if you hit the geartronic trigger on the throttle its smooth acceleration the whole way through which makes me think its leaning toward the MAF sensor or TPS. If it were a fuel issue Id be running into to fuel cut through out the throttle, also if the TB sensor is bad or the plate is sticking it would make sense that the throttle opens completely with the trigger enaged and stays open where as building boost in fourth it would have to be gradually opening and sticking. Thats my two cents. Ill be replacing the MAF sensor first and it that doesnt help ill move onto FPS and than TB. Ill be sure to keep this thread updated. Even with the lack of our piers help.
 

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Also Drew, I notice this was from 2012 if you resolved your issue let me know what it was so i can move forward efficiently. Thanks. -Derrick
 

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I've been have a very similar issue and I have reason to believe maybe it's the fuel pump?

Creeping into boost I get the stuttering /sputtering feeling but when I put my hove in it it runs strong at WOT.

Edit: here a clip that may help explain listen close after take off you can hear two short spudders, does that sound similar to what your getting ?
https://vimeo.com/136282436
"Embody god... Then go crazy"
 

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It would be the other way 'round if it was the fuel pump... sounds to me like it could be the fuel trim is too rich at that point in rpms.
 

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That was gonna be my next point but all I'm running is pure 91!


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Where is the fuel distributor on these cars, I read up that fuel additives have corrosive properties and this issue started after I was using them pretty often.

When I stopped using them the problem subsided but now it's back again for some reason.


"Embody god... Then go crazy"
 

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I have a good fuel sending control unit and brand new wiring harness if anyone needs.... Also a map sensor. 05. T5.
I spent crazy money on my fuel delivery and bank 1 lean codes. Turned out. I just had the FPS for non turbo in. Tons of time and money. I also replaced. TCV and TCV valve.
Almost 200k miles and runs like new.


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I had the same problem on my -08 s40 t5, replaced maf, engine temperature sensor, fuel pressure sensor and spark plugs. Did not help, so my guess is o2 sensor, fuel pump or maybe throttle-related.
 

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I want to eliminate as many variables as possible so I'm not swapping parts left and right.

So I've
-swapped out FPS
-cleaned the MAF ( symptoms appear with both open and closed intakes)
-new elevate tcv
-new plugs

Have used gas from several stations always 91 on an elevate tune, some difference noticed between shell and chevron but nothing consistent.

Have used additives and cleaners including
-marvel mystery oil
-sea foam
-royal purple octane booster

Symptoms appear both on and off additives, But only after using octane booster more than three times.
Right now these are my main culprits I'm wondering if maybe the sea foam knocked some gunk loose or if the additives corroded a line.

I will take off the inter cooler- throttle body tubing and see if there's a collection of oil at the bottom that could shed some light on a possible throttle issue.




"Embody god... Then go crazy"
 

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I want to eliminate as many variables as possible so I'm not swapping parts left and right.

So I've
-swapped out FPS
-cleaned the MAF ( symptoms appear with both open and closed intakes)
-new elevate tcv
-new plugs

Have used gas from several stations always 91 on an elevate tune, some difference noticed between shell and chevron but nothing consistent.

Have used additives and cleaners including
-marvel mystery oil
-sea foam
-royal purple octane booster

Symptoms appear both on and off additives, But only after using octane booster more than three times.
Right now these are my main culprits I'm wondering if maybe the sea foam knocked some gunk loose or if the additives corroded a line.

I will take off the inter cooler- throttle body tubing and see if there's a collection of oil at the bottom that could shed some light on a possible throttle issue.




"Embody god... Then go crazy"

Did you change the Gap on the plugs or stick with stock? Im nearly 100 that its the gap in the plugs and causing sparkout and misfire. I have 3 tunes; Stock, Modified 2 or Stage 2 and Stage 3. Its not mechanical in nature. No fuel codes, no MAF codes, one misfire code and absolutelt NO issues in the stock tune.

If it were a fuel issue our PCMS would be on it, same as TB issues. The PCV is new and until it throws P0089 I believe the FPS is not getting replaced.
 

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I didn't mess with the gauging at all I left them as is, wonder if I should swap them out with some new coil packs as well that's what my mechanic suggested anyways.

And good call on the codes I figured out system would start sending some sort of messages.


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I didn't mess with the gauging at all I left them as is, wonder if I should swap them out with some new coil packs as well that's what my mechanic suggested anyways.

And good call on the codes I figured out system would start sending some sort of messages.


"Embody god... Then go crazy"
Its a difficult DIAG with no CELS but thats what made me think tune... Something to do with fuel cut or bad fuel would relay a fuel code dtc and the same with MAF and what not. The one code you wont get until its too late from what I understand is the PCV code. Anyway it had to do with timing and ignition given the stock file holds up with no issues and as soon you go into boost in stage 3 you get misfires.
 

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I was tempted to run it without the tune for a while but i don't really want to be taking it on and off but I have very similar symptoms, if I creep into boost I'll get the spudder. At wide open throttle it usually holds pretty strong until it shifts.

What plugs are you running I have NGK double iridiums.


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I was tempted to run it without the tune for a while but i don't really want to be taking it on and off but I have very similar symptoms, if I creep into boost I'll get the spudder. At wide open throttle it usually holds pretty strong until it shifts.

What plugs are you running I have NGK double iridiums.


"Embody god... Then go crazy"
So long as you still have the 02s connected the stock file is safe to run whenever you feel the need. I do in the winter when I have to drive the C30.

I was told to use the NGK IV LFR7AIX .24 pre-gapped. They should be here by tomorrow and hopefully on. I believe it will correct the problem all together. Ill be sure to let you know how it goes. Keeping my fingers crossed. Im more likely to do coil packs before I go the FPS or MAF route.
 

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I'm having the same stutter, only around 2500-2800 rpm on part throttle on my 05 V50 T5 with Shark Stage 3.

So far I have replaced:
- CBV
- MAF
- FPS
- cleaned the throttle body
- sparkplugs, gapped correctly
- TCV

I'm only running BP Ultimate 98 fuel (I guess that's 91 in the US)... It got better after replace in the FPS and cleaning the throttle body, but came back after a while. Doesn't seem to happen when the engine is cold, so that might point in the direction of the front O2 sensor. Car is due for a 140.000km-service + timing belt change, I guess I'll see if it's still there after the big service.
 

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I'm having the same stutter, only around 2500-2800 rpm on part throttle on my 05 V50 T5 with Shark Stage 3.

So far I have replaced:
- CBV
- MAF
- FPS
- cleaned the throttle body
- sparkplugs, gapped correctly
- TCV

I'm only running BP Ultimate 98 fuel (I guess that's 91 in the US)... It got better after replace in the FPS and cleaning the throttle body, but came back after a while. Doesn't seem to happen when the engine is cold, so that might point in the direction of the front O2 sensor. Car is due for a 140.000km-service + timing belt change, I guess I'll see if it's still there after the big service.
Cool more great info thanks, so there's two new bits of info from two sources;

- does not appear on cold start
- apparent on two different tunes ( elevate and shark)




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