VR6 Bora Hesitates on acceleration

[WhO]

I'm not sure if disconnecting the ecu will actually reset it, it might but i'm not 100% sure, probably worth a try!

As far as the TB goes, i've never had to re-align it. After plugging in the battery again when you first turn the ignition on you can hear it open and shut a few times to calibrate itself.

[Dyldo]

ok, so how do i reset the ecu?

[WhO]

Just did a whole bunch of web browsing and concensus is that unpugging the battery for 30min-1h seems to do the trick. To be sure i'd clear fault codes before doing this even if there are none (as this is meant to clear fuel trims too) and then unplug the battery. Maybe just unplug it overnight to be sure, cant hurt!

As far as throttle alignment when you plug the battery back in turn the ignition to on and let it sit there for say 10-20 seconds so it can work itself out. Then start it up.

[Dyldo]

UPDATE
OK, I reset the battery overnight, reconnected and heard the TB aligning itself. Started her up after a minute or so, and everything sounded great.
Plugged Launch CReader in and got no fault codes at all (which worries me actually) and then took some values from the data stream - see below.
Then I went for a drive, and in 2nd gear went to WOT to get more values in the live data stream - no real change to floor and ceiling values. And then sure enough after a few hundred meters of test we get the hesitation and stuttering, and by the time i get back to my driveway i have a P0305 code (Cyl 5 misfire) - which I am sure is not the only fault code but i am not learned enough with the Launch yet.
Calling JMAC!!

Anyway, here's some values:-
max g/s flow of MAF - 120
idle flow of MAF approx 3.5 to 4.0 g/s
engine rpm 760
coolant temp 85
short term fuel trim 1 floor of (12%) to ceiling of 12%
short term fuel trim 2 floor of (8%) to ceiling of 7%

I am sure there were more just can't remember them.
Thoughts?

[Dyldo]

oh, and these values are with a brand new MAF and newly-oiled (lightly) air filter, and the new plugs and coils as mentioned.

I think I remember timing at idle was 12deg?

[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?