S4 Tii Sputters At High Rpm
04-26-2004, 07:44 PM
#1
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Join Date: Nov 2002
Location: Lynwood WA
Posts: 275
A friend of mine has a S4 TII that is basicly stock with a few exhaust modds. On his boost gauge it never goes past .5 bar (7.3lbs) which I believe is under fuel cut but when your on the freeway if you shift into 4th the car will sputter occasionaly when it goes over about 5000rpm. The fuel filter was just replaced by me and it still does it. It has only cut out in 2nd or 3rd maybe 2-3 times its almost always fine 1st-3rd all the way to redline. Any ideas on what it could be???
04-26-2004, 07:53 PM
#2
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Join Date: Mar 2004
Posts: 39
What are the few exhaust mods?
From what you describe, it is fuel cut most likely. Get an FCD. 7.3 psi is very close to fuel cut. The gauge may be inacurate and the pressure sensor might be getting pressure from a different source then the gauge. I've hit fuel cut before at ~7-8 psi indicated and it feels just like what you described. Usually only happened in 3rd gear or higher.
From what you describe, it is fuel cut most likely. Get an FCD. 7.3 psi is very close to fuel cut. The gauge may be inacurate and the pressure sensor might be getting pressure from a different source then the gauge. I've hit fuel cut before at ~7-8 psi indicated and it feels just like what you described. Usually only happened in 3rd gear or higher.
04-26-2004, 08:08 PM
#4
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Join Date: Nov 2002
Location: Lynwood WA
Posts: 275
Exhaust modds are RB down pipe and some kind of dual 2.5 catback, im pretty sure cats are still there other than the one I think the DP eliminates
I think im going to have him put some new plugs in it and I might let him borrow my FCD to see if thats it. One thing I noticed looking under the hood was that the boost gauge was T'd into the line for the boost pressure sensor, is that bad? I have no clue where else to T" into because my car has no emissions so mine is just ran off a spare nipple on the UIM
I think im going to have him put some new plugs in it and I might let him borrow my FCD to see if thats it. One thing I noticed looking under the hood was that the boost gauge was T'd into the line for the boost pressure sensor, is that bad? I have no clue where else to T" into because my car has no emissions so mine is just ran off a spare nipple on the UIM
04-26-2004, 10:05 PM
#7
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Join Date: Dec 2001
Location: Jensen Beach, FL / Sylva, NC
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There is a "pill" in the line from the Manifold to the boost pressure sensor. If this is removed your ECU gets all confused. Common mistake is to replace the vacume lines and toss the pill with the old line. Not knowing its in the line.
04-26-2004, 10:14 PM
#8
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Thread Starter
Join Date: Nov 2002
Location: Lynwood WA
Posts: 275
Im pretty sure it is, he says the line just got spliced for a T and that was all he did to the line for the boost pressure sensor. I think we might pull out the fuel pump and see how the filter in there looks. thanks
04-27-2004, 08:57 AM
#9
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Join Date: Mar 2004
Posts: 39
First thing i would do is put an S4 FCD on there and see if its better. If it isnt better then go through everything. Plugs, wires, in tank fuel filter, air filter. My NA sputtered or misfired at 5500rpm and it turned out it was a bad leading coil, but it would do it in every gear at about the same rpm.
