EPC light power issues help!!!

[cameron90]

hey everyone, ive got a huge issue with my b5 s4 and im not sure what the cause is. the EPC light is on in the dash cluster and whatever the problem is once i hit around 4-4.5k rpm i lose higher rpm power the power just stays as if it cant go past 4k rpm. i need help please!!

not sure if its the throttle body brake sensor or crankshaft sensor, if someone knows how to fix this issue id greatly appreciate your advice or help.

[zillarob]

You need to scan it with something like vagcom.

[cameron90]

no codes are showing up unfortunately but hopefully that narrows down some ideas.

[Zba]

EPC light and no codes? Are you using a VAG-COM or similar or a 20$ code reader? Not that it should matter.

Check the plug on your throttle body, verify that your brake lights work as designed, try a throttle body adaptation.

[zillarob]

If there is a light on, there are either codes, or it is dead and you cant communicate with it.
Needs to be scanned with a legit scanner. The generic ones usually only show the obd2 stuff, but not the mfg specific goodies.

[cameron90]

If there is a light on, there are either codes, or it is dead and you cant communicate with it.
Needs to be scanned with a legit scanner. The generic ones usually only show the obd2 stuff, but not the mfg specific goodies.

There is no codes coming up its a vag-com my mechanic thinks its the ecu a may need to be reprogrammed

[papuc14369]

Just the EPC light? It may be your wheel speed sensor or ABS sensor, or a simple as your brake light sensor. Scan with vagcom and report back.

[hibiscusS4]

Last time i got an epc light it was a malfunctioning ecu

[cameron90]

Last time i got an epc light it was a malfunctioning ecu

So what did you end up doing? Did you have it reprogrammed?

[cameron90]

scanned with vagcom absolutely no codes pop up it has to be a bad ecu.?

[Zba]

Stupid question: you are scanning all control units right?

[cameron90]

Stupid question: you are scanning all control units right?

Only one code pops up and thats the epc warning, im getting my ecu flashed it seems to be the issue im having a local authorized shop do the apr ecu upgrade 1 tune

[cameron90]

Only one code pops up and thats the epc warning, im getting my ecu flashed it seems to be the issue im having a local authorized shop do the apr ecu upgrade 1 tune

So turns out its not that i need my ecu flashed, no codes and not the ecu it has to be a wiring issue or a short somewhere. Any ideas guys?

[Zba]

Cleam the throttle plate, do a throttle adaptation, if it persists swap tb with a known good one.

[cameron90]

Cram the throttle plate, do a throttle adaptation, if it persists swap tb with a known good one.

Well it doesnt seem to be the throttle body i must be an electrical issue

[Zba]

Did you swap with a known good one?

[cameron90]

Did you swap with a known good one?

I havent swapped the tb, but if i had a bad fuel filter would that throw on the epc light?

[Zba]

what do you mean by "bad"?

You go from being certain it's electrical to a bad fuel filter..?

Do you understand how EPC works? It might be time for you to do some reading.

[cameron90]

what do you mean by "bad"?

You go from being certain it's electrical to a bad fuel filter..?

Do you understand how EPC works? It might be time for you to do some reading.

I come here for help with the issues at hand not to be critisized. I had the ecu reflashed to make sure it wasnt the ecu, that wasnt the problem my mechanic said he thinks it could be an electrical issue or a few other things, he thinks he has narrowed it down to the fuel filter. Those are his words not mine. And i was asking if a crap fuel filter would throw the epc light on? After 4.5k rom in any gear the power is at a stand still as if its not allowing me to drive it harder

[cameron90]

I come here for help with the issues at hand not to be critisized. I had the ecu reflashed to make sure it wasnt the ecu, that wasnt the problem my mechanic said he thinks it could be an electrical issue or a few other things, he thinks he has narrowed it down to the fuel filter. Those are his words not mine. And i was asking if a crap fuel filter would throw the epc light on? After 4.5k rom in any gear the power is at a stand still as if its not allowing me to drive it harder

Fuel pump

[Zba]

Not trying to criticize. If you want to own one of these it is a really good idea to educate yourself on the car. But a scanner and go from there. Search "Julex scanner" he posted one for 60$.

I was also under the impression that you were doing the work yourself.

If your mechanic is thinking fuel pump, do you have a solid Epc light or does it come on under boost? What's the real deal?

[cameron90]

Not trying to criticize. If you want to own one of these it is a really good idea to educate yourself on the car. But a scanner and go from there. Search "Julex scanner" he posted one for 60$.

I was also under the impression that you were doing the work yourself.

If your mechanic is thinking fuel pump, do you have a solid Epc light or does it come on under boost? What's the real deal?

The epc light is solid. Not quite sure what the issue is but im def restricted in using full power

[cameron90]

The epc light is solid. Not quite sure what the issue is but im def restricted in using full power

Forgot to mention that my fuel economy sucks so maybe it is the fuel pump. Im only getting like 240 miles on a tank with average driving.

[Zba]

That's about normal.

[cameron90]

Im starting to think that i might have a bad coil

[cameron90]

so it turns out that is was the after market coil set up, the coils ignition control module and fuel pressure regulator. glad that thats all it turned out to be

[cameron90]

Turns out it was all wrong. It was a few hoses and my bov's werent fully tightened so boost was hardly boost. Also relay needed to be replaced. And more good news on a side note i found out my s4 has been tuned/ecu flash by MTM


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[vavJETTAw36]

Well which issue is it? I don't see how any of what you mentioned could affect the EPC. The EPC is traction control......


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[Jism]

An engine fault can throw the EPC yes. If the ECU was dead i dont even think it would start at all.

[Zba]

Well which issue is it? I don't see how any of what you mentioned could affect the EPC. The EPC is traction control......


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ESP is traction control (electronic stability control), EPC is throttle intervention (electronic power control or similar).

[cameron90]

I said epc it was two relays nehind the ecu that kept causing it


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