ALFAGTV6.COM

Hi all,
Got my GTV6 running the other day and all was going really well until cylinders 3 and 5 stopped operating at all. Both at the same time.

I have verified that I have spark.
When I disconnect the injector plugs nothing changes in engine behavior.
Can I check the electrical connection to the injectors by hooking up a spare one and dipping it in water or something? Will it make bubbles if it's working? Or should I use a multimeter or something.

Injectors are higher flowing ones from Greg. Are there other things I could check first like intake runners or something? These are new too.
There seems to be a hissing sound more so than normal too. All vacuum lines connected and no leeks in the intake hose as far as I know.

One other thing that I should mention is that some water got into the fuel tank due to an open petrol cap. Would this affect it? even if it did affect I wouldn't think that it would only affect 2 cylinders.

Thanks in advance for any assistance.

Alfettish The first thing I would check,given your description, is the injector grounds on the rear passenger (driver's - side if you have RHD) valve cover.Have a look at this post it may be useful.

http://www.alfagtv6.com/bb/viewtopic.ph ... light=noid

Thanks Murray.
Grounds are totally OK. One thing I noticed though, there are only 5 leads going into the ground grouping so is there a 6th somewhere?
Next I will test with the noids. Impedence?

I'm so frustrated! Today I was supposed to compete in my first hillclimb.

Alfettish

One thing I noticed though, there are only 5 leads going into the ground grouping so is there a 6th somewhere?

Working from memory I don't think there are 6 ground wires so just make sure the wires are solid in their crimped connectors and that the ring terminal to valve cover surfaces are clean.

The idea of the "noid" light is not to measure impedance.The injectors turn on/off so quickly (when they're working) 1-2 ms @ idle, that a multimeter can't pick up the signal.So you can either make up a tester (see attached) or get one from your local auto-parts store.

Injectors are supplied a constant +12V by the comb-relay when the ignition is on and the injectors are switched on when the L-Jet ECU creates a signal path to ground based on input from the distributor hall or variable reluctor sensor.

So what you need to do is turn on the ignition and confirm that you have +12V at the connectors for the missfiring injectors.Next use the "noid"light between both terminals of the injector and confirm that the LED pulses when the engine is cranking or running.If it does then the injectors are getting the appropriate signal and are not delivering fuel because they are blocked or faulty.

Thanks Murray.
Tested the injector with a noid light. All seemed normal, there was a pulse in the injector.
I then tested the cold start injector because now the car won't even get running The light was waaaay brighter but constant.
I then tested the missing injector and there was no light. I tested a good injector and no light.
What the hell is going on? All fuses are OK.

Alfettish the result you got on the cold start injector was normal.It isn't really an injector like the others as it doesn't pulse on/off it stays on during cold starts.

First thing to confirm is that your ECU is getting high enough voltage from the battery.If it is dropping below approx.11.5V then things get weird.If your battery is OK you need to confirm that you are getting 12V at the injectors with the ignition ON.Use a multimeter.

check you 'noid' light...if you have two , use the other

sounds like wiring/ground problem...but may be fuel computer injector driver

I would pick up a few 'bosch' type injector connectors and rewire the engine bay portion of harness and ground new harness to block

or try a different ECU

FIXED!
Injectors causing the too-rich running. Standard injectors now in and running fine. There was lots pf petrol in the oil too... The reason for missing cylinders afterall was fouled plugs due to the richness.
Also did a base-line dyno run and got a whopping 86.0 KW at the rear wheels.

better than a wiring problem!!

Esteemed colleagues of this forum, in particular Alfettish, Murray, and X-rad:
I bought 2 weeks ago a good looking grafite GTV6 - 2.5.
I did a test drive and all seemed perfect. Started well, brakes well, change gear well so I decided to pay. After dinner I could not resist take a ride and after 30-40km, suddenly the engine began to loose power and began to misfire.
I stopped to see the spark plugs and noticed all Lodge 2HL were completely fouled with black carbon. I quicly cleaned all 6 spark plugs and the car run well again for more half a hour. Next day I decided to buy a new set of Logde "candles" and the car run another half hour without misfire problem, than it starts everything again.
Before I report this anomaly to all of you, I read all the forum to see something similar, but, besides I could find some sililarities in 1 or 2 cases, I supose mine is diferent.
It seems the misture runs very rich fouling all the plugs, and I don´t know how to control this situation. The old owner left old injectors ass´y in the luggage compartment, so it seems he changed recenly all injectors , but aprently did not solve his problem.
Could some of you give me an idea how to aproach this problem before I go with the car to a Bosh Service or Alfa Service? Thanks in advance.
Clouseau - Portugal