annoying misfire on g40

[benh999]

Right folks quick update.  Andy had a thorough look over the car today. Both Cam and ignition timing are spot on. CO pot is  reading spot on. throttle body seems to be good, blue temp sender fine.

Yet to be 100% confirmed however it seems the Lambda could be one of my main problems.  Drove home with it disconnected and car drove almost like normal.  Need to check the wiring to the ECU as well.

WE have a list of things that need addressing before live mapping session takes place.

Change Earth straps(charger one missing, others looking not too clever)
change knock sensor (current one not looking too clever)
change vacuum pipe and clips from fuel pressure regulator.
Change HT leads
New alternator.(current one only kicking out 13.5amps at idle)  with fan on only 31.1amps)

Good day in all :-)

[Max]

Im confused, aren't you selling this?

[samg40]

Yep my car last year wouldnt turn over on the key and the battery kept discharging because the charger earth strap wasnt conncted properly and knackered. After I replaced it, car ran perfect, that little strap makes a hell of a difference.

[benh999]

Im confused, aren't you selling this?

Yup probably selling her.  Finally found what I want and the g40 is just a bit too harsh for my daily needs.  However I'd rather the car to be mechanically perfect when I sell her.

[Andy]

Deffo sort all the earths out first - that dodgy knock sensor connector isn't brilliant either, neither is the hose to the fuel pressure regulator. New HT leads and a dizzy cap and rotor arm wouldn't be money wasted either.

Then see what you get at the battery from the alternator, and how it runs then.

If the voltage is okay and it's still miss-firing a bit on light throttle I'd look at the lambda. Did you find out from the previous owner what wiring problem he'd had there, and how he fixed it?

I think the 'jumpyness' pulling away is partly down to a dewedged throttle body, made worse by the miss-fire you've got - so you'll never completely irradicate that unless you stick the wedges back in. Problem is, that the MAP sensor value swings around a fair bit for next to no throttle input - which makes it very difficult to map in that area. With the wedges back in the MAP value is more progressive/stable at low throttle openings.