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Why won't my car rev past 5000 rpm?

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Old 09-23-07, 11:11 AM
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Why won't my car rev past 5000 rpm?

Tried searching but could not find much useful info.

i've got a S5 TII that runs out off power at 4500/5000rpm.

Just won't go past that 5000?
Old 09-23-07, 11:30 AM
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could be any number of thiings..

clogged cat/exhaust
not all the fuel injectors are firing
bad coil
clogged intake
bad TPS or MAP
throttle cable needs to be adjusted
plugs need to be replaced
fuel pump is going bad
dirty fuel filters
rust in the fuel tank
Old 09-23-07, 10:23 PM
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my motor cuts at 6500 ('87 TII) and I haven't figured it out either. I just ported my wastegate, the tank is clean, the pump I hope is fine, I just have a downpipe right now (almost 0 restricion = LOUD)... I'm pretty sure all my injectors are firing, I get a large increase in exhaust noise when I pass 2800RPMS, even at a snail's pace.
Old 09-23-07, 10:41 PM
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You guys aren't pushing the pedal far enough.
Seriously though, try doing all the little tuneups and you should be fine.
Old 09-23-07, 10:54 PM
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I'm wondering what 'little tuneup' I might have missed... the ONE thing I can think of that may help that I haven't done already would be fixing my grounds. every once in a while I do get the 3800 RPM hesitation.
Old 09-23-07, 10:55 PM
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What about checking all the grounds?
Old 09-23-07, 11:03 PM
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Grounds helped me ALOT, even though I only did the main one. =)
Old 10-01-07, 10:49 PM
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Just chiming in, not an expert on stuff or anything, but the throttle cable and the secondary fuel injectors including ECU grounding are mostly the source of these problems w/ the 3800 rpm hesitation, plugs/coils RARELY are the cause, just from experience, I did a tune-up, new plugs, wires, fuel filter and then a week later the car started doing the hesitation, no power under load, car still runs, but no power whatsoever.

Now, for some odd reason, going for a stand-alone FMU, these problems seem to be NON-EXISTENT at all. Again, by experience. Anybody have any explanation on why this is happening? Just a hunch, all of these "little" things to fix is most likely a TEMPORARY resort, most of the time, some of us still have the hesitation.

Just my 2 cents, electrical stuff on the 2nd gens (but compared to the FD's, these should be a breeze---if you know what you're looking for) are a ******* pain. Replace the ECU harness, change/get rid of vacuum lines that are not needed, most of the time, this ***** up everything else that should be working in order.

Not all of you would agree, of course, I mean who has the money to buy a brand new harness when we all just want to enjoy working with cars like these?

Oh and yeah, forgot about the TPS and the MAS, who wants to deal with that? Another thing to go by is the oh-so popular BAC valve (which doesn't do squat as oppose to the troubleshooting that's inside the Haynes' and FSM), I know this because my BAC valve hasn't been functioning for a year and I didn't even know it till someone told me(YES, I WAS ONCE A NEWB).

Last edited by boma; 10-01-07 at 10:53 PM. Reason: add new sentence
Old 10-15-07, 03:28 PM
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Well i got round to doing the grounds at the weekend, and it seems to be smoother getting to 5000 but i still got the problem?
and now an occasional bouncing idle!!!

Here's what has been done recently:
New plugs
Oil Change
New oil filter
New Leads
Grounds

i've also got the problem where, when i boot it round a sharp left bend
the revs drop and the engine almost cuts out.
Old 10-15-07, 04:07 PM
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From what I know, the last problem /\ is sometimes cause by the fuel sloshing around when the tank is low. The pump sometimes cant pick up enough.
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