C20XE Running Problems - Badly Overfueling

[Scoobler]

Hello,

Will appologise now as this will probably be a long post, but really in need of some help

My cav has been off the road for a while, here's how it all started:

• I put reprofilled cam's into my car, it was running sweet as a nut.
• It started to overfuel a little on overrun (high rev's, foot off the gas, still in gear), it was 'burbling' and if you lightly touched the throttle it would pop lightly.
• When the cams went in some of the caps didn't tighten properly, a metalic rattle developed which I though was the cam coming loose. I helicoiled the holes. It turned out the rattle came from the PAS pump (two of the three bolts had come out)
• As I started work a few weeks before this problem developed and I got a works car it has taken about 3 months of trying to get it on the road.
• After getting it running after the helicoils, I had a good look over it. Turned out the exhaust manifold no1 port had almost completely cracked seperate from the rest of the system (so lambda would be miss reading and cause overfueling?), also replaced the CTS as I had never replaced it and thought that could help the overfueling.
• Also the ECU light was on saying there was a problem with the MAF meter so replaced that with a cheap after market one (Mapco thing from KPS Auto's) and replaced the exhaust manifold.
• The ECU light came on again, said it had a problem with the Air Temp Sensor, turned out the wire had snapped in the connector, so replaced the connector.
• The car was running dog ruff, very erratic idle and a miss fire.
• Put in some new HT leads, spark plugs, changed the oil and oil filter and the ICV (parts from autovaux).
• Running was exactly the same. Spark plugs were ALL very black. After 2 minutes of running the new plugs, removed and they were also black.
• Took the car for a quick drive, at low revs it would missfire, if you put the clutch in it would stall. At high rev's (full throttle it would be fine - the TPS was new about 12 months ago). On the way back I unplugged the MAF meter and it drove a hell of a lot better, no missfire and the idle was almost perfect (the slight lumpyness that was left could be down to the cams).

Right I know the MAF meter needs replacing (proves you get what you pay for so it can go back), should I also replace the lambda with an original?

What else would cause overfueling, what else do you think is wrong if its not MAF or Lambda?






Thanks for reading all that, really hope someone can help!

[namkeaps]

maybe try a different ECU? might sound mad but worth a try as it maybe reading/sending the wrongsignals or summat?

prolly bit far fetched for it to be something like that but worth a mention i though mate

[Scoobler]

Its possible, will have to try and find someone with the right ECU - I think its the Motronic 2.8 one (dis pack) iirc.

[Scoobler]

Could the Hall Sensor be faulty?

[Neve'o]

mine did something very similar and it turned out to be the 02/lambda sensor. you can get cheap ones off ebay, so may be worth trying. i did buy a gm o2 sensor and it lasted about 2/3months before going wrong, ebay one has lasted 7months and still going.

[Scoobler]

I have ordered a new Lambda (£14 from ebay), will give that a try when the new MAF meter arrives.

Have also been thinking about gettin a wideband lambda & controller with analogue output, apart from anything to show the AFR - is it worth it?