VR6 Bora Hesitates on acceleration

[Dyldo]

UPDATE
I went out and took some more values from my Launch reader. I am a massive nooblet and don't know how to read these fandangled doovy whackers, but is it showing that a o2 sensor (Lambda?) is dying valiantly?
Or, otherwise, what else is it showing in conjunction with the above readings?

[Dyldo]

Also found this nugget and thought it was awesome (i'm learning)
Th*e oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.

[Dyldo]

Sorry to keep posting on my own thread here but I think I'm going nuts doing all my self-diagnosing like webMD.

- Lambda sensors / exhaust oxygen sensors
As the sensor ages, it becomes sluggish. Eventually it produces an unchanging signal or no signal at all. When this happens, the Check Engine Light may come on, and the engine may experience drivability problems caused by an overly rich fuel condition. Poor fuel economy, elevated CO and HC emissions, poor idle, and/or hesitation during acceleration are typical complaints.

If the average voltage from the lambda sensor is running high (more than 0.50V), it indicates a rich condition, possibly due to a bad MAP, MAF or Air Flow sensor or leaky injector. If the average voltage reading is running low (less than 0.45V), the mixture is running lean possibly due to a vacuum leak or because the sensor itself is bad.

If the lambda sensor continually reads high (rich), it will cause the engine computer to lean out the fuel mixture in an attempt to compensate for the rich reading. This can cause lean misfire, hesitation, stumbling, poor idle and high hydrocarbon emissions (from misfiring).

Sometimes an apparent lambda sensor problem is not really a faulty sensor. An air leak in the intake or exhaust manifold or even a fouled spark plug, for example, will cause the lambda sensor to give a false lean indication.

[Coralon]

Yeah it all points back to that misfire on pot 5, if you can find the cause of that first then you will be able to follow the issue to the oxygen sensor... if it really has one which it may not. Try swapping the plug from 5 and see if the misfire moves, if it doesnt then you can look at coil leads etc. If it does move then you know its the plug.

[Dyldo]

but I don't necessarily trust the Launch Error codes. How can the car have so many issues and only throw a single error code for cylinder 5?

[Coralon]

Well its not that the car has so many issues, its that the misfire is causing more problems with other sensors. The hesitation is going to be spark or fuel related and everything from there is going to affect engine and cam timing etc compounding things and making it feel worse than it really is. Identify the cause of the misfire and most likely all the other problems will automagically go away.

[Jmac]

Just remember this , scanners, even as powerfull as VCDS and even the VW one are only the icing oin the cake mate. They are all too slow. even though VCDS has the turbo mode its still too slow. No faults found doesnt mean no faults. Its just the parameters of all the sensors are somewhat near what the ECU needs to see. Sorry to be long winded but here is an example of what im trying to say - Just had an ABC engined A6 chewing fuel and running crud when warm. No faults on any scanner. Customer complaining of chewing fuel etc. So he is the man driving it everyday and knows when something isnt right. decided to scope the o2 sensors. With the scope connected pulled the brake booster line off to draw loads of secondary aor andthe o2 sensors should have went haywire, but nup, really slow but working so dumb ecu didnt detect any drama. fitted new o2 sensors and fixed, Sorry for the long wind but just trying to say dont totally rely on fault codes or scanners. If it wer me i would smke test the intake and check for secondary air, if its all tight including evap lines then you can rule any of that out, easy test and confirms tight system. The hesitation is due to bad combustion so if the intake is good be checking fule , filter and pressures including flow
Keep us posted
Jmac

[Dyldo]

cool - where can one get a smoke test?

[Dyldo]

well, I haven't picked her up yet but it appears all it was was a dodgy coil on pot 5 and a TB relaignment. she is apparently all ready to rock and/or roll.

but to my mind, won't that mean i still have o2 sensor issues from the screen readings on page 2?