Sensors, a completely uninteresting entry but a good primer non-the-less.
So, when one increases the volume of air into a motor, concomitant modifications must be made to the rest of the motor to achieve air/fuel balance. Increasing air induction without simultaneously increasing the capacity to inhale (intake) more air as well as exhale (exhaust) more air ruins engines (meaning you need larger and more robust: intake, intake manifold, MAF housing, intake piping, intercooler piping, hoses to which I have 13, diverter valves, downpipes, headers, cats, and cat-back).
Also, on the fuel side of the equation, increasing boost by nearly 180% above stock configuration necessitates an increase in the capacity to feed the motor even more fuel (meaning, typically, larger injectors, fuel rail, fuel pressure regulator, and fuel pump). Furthermore, a new ECU or program must be written to manage all the new changes.
What I've recently run into are sensor problems. In a nutshell, a myriad number of sensors (of which I truly believe I have more of then any car in existence) monitor, measure, and transmit data to the ECU. This data is electronically digested with the ECU deciding exactly how much fuel or boost pressure or timing retardation or timing advancement etc. required with regard to optimum engine performance...of course, all of it is done in milliseconds. The bottom line with sensors is when you have bad readings, it's not just an issue of poor performance...we're talking about detonation, major MPG loss, throttle cut, bucking on acceleration, all with the possibility of breaking hardware.
When an S4 undergoes a Stage III upgrade, the existing sensors often times can't cope with all the new crazy readings. The sensors might have had no problems with readings within the standard bell-curve, but we're talking outrageous outliers here. After hours and hours of research, online forum chatting, and logging and scanning of my ECU with thePerfectline's laptop VAG-COM controller, I've narrowed all the problems down to the following sensors which I've slowly over the past weeks worked on finding the best and cheapest alternatives to.
MAF: Mass Airflow Meter: measures the amount of air entering the intake. Easy to replace.
N75: Wastegate actuator control unit. Interprets boost pressure and controls when the wastegates open or stay closed. Each of those nubs connects to THREE vacuum lines EACH...yuck. Not to bad replacing, a couple of hours.
EGT Sensors (2): Exhaust Gas Temp sensor. These bad boys are a pretty penny, but are integral to optimal if not normal engine functioning. A pain in the ASS to get to. Mechanics will charge you 6.5 hours of labor for the driver and 2.5 for the passenger side...you're talking 1000 bucks if you have it done by a shop. It took me pretty much the whole weekend but I banged it out in I'd say about 6 hours total.
Coolant Temp Sensor, green top: Why? Because the motor is actually running too cool. Crazy.
And finally, O2 sensors (2) Primary: Also quite an expensive part. Dealers will AGAIN charge you 1 grand to do this job...I'm tackling it this weekend. Damn, look at all the wires.
AND I'll also be pressure testing ALL MY VACUUM LINES. You don't want to know how many the S4 has. Borrowed theCraftsman 150 PSI air compressor for the job and put together a bad-ass pressure tester for this project.
Will let you know how it all goes.
EGT Sensor.
Also, on the fuel side of the equation, increasing boost by nearly 180% above stock configuration necessitates an increase in the capacity to feed the motor even more fuel (meaning, typically, larger injectors, fuel rail, fuel pressure regulator, and fuel pump). Furthermore, a new ECU or program must be written to manage all the new changes.
What I've recently run into are sensor problems. In a nutshell, a myriad number of sensors (of which I truly believe I have more of then any car in existence) monitor, measure, and transmit data to the ECU. This data is electronically digested with the ECU deciding exactly how much fuel or boost pressure or timing retardation or timing advancement etc. required with regard to optimum engine performance...of course, all of it is done in milliseconds. The bottom line with sensors is when you have bad readings, it's not just an issue of poor performance...we're talking about detonation, major MPG loss, throttle cut, bucking on acceleration, all with the possibility of breaking hardware.
When an S4 undergoes a Stage III upgrade, the existing sensors often times can't cope with all the new crazy readings. The sensors might have had no problems with readings within the standard bell-curve, but we're talking outrageous outliers here. After hours and hours of research, online forum chatting, and logging and scanning of my ECU with thePerfectline's laptop VAG-COM controller, I've narrowed all the problems down to the following sensors which I've slowly over the past weeks worked on finding the best and cheapest alternatives to.
MAF: Mass Airflow Meter: measures the amount of air entering the intake. Easy to replace.
N75: Wastegate actuator control unit. Interprets boost pressure and controls when the wastegates open or stay closed. Each of those nubs connects to THREE vacuum lines EACH...yuck. Not to bad replacing, a couple of hours.
EGT Sensors (2): Exhaust Gas Temp sensor. These bad boys are a pretty penny, but are integral to optimal if not normal engine functioning. A pain in the ASS to get to. Mechanics will charge you 6.5 hours of labor for the driver and 2.5 for the passenger side...you're talking 1000 bucks if you have it done by a shop. It took me pretty much the whole weekend but I banged it out in I'd say about 6 hours total.
Coolant Temp Sensor, green top: Why? Because the motor is actually running too cool. Crazy.
And finally, O2 sensors (2) Primary: Also quite an expensive part. Dealers will AGAIN charge you 1 grand to do this job...I'm tackling it this weekend. Damn, look at all the wires.
AND I'll also be pressure testing ALL MY VACUUM LINES. You don't want to know how many the S4 has. Borrowed theCraftsman 150 PSI air compressor for the job and put together a bad-ass pressure tester for this project.
Will let you know how it all goes.
EGT Sensor.
posted by supergoober at
5:39 PM
1 Comments:
My lord man, are you not totally over this car?
I say once you get it running perfectly you should throw some dessicant packs in the cabin, and then saran wrap the entire car, park it in your garage, and never drive it, ever again, just to make sure it doesnt break ever again!
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