Running on three cylinders
 

Hi guys

have a bit of a problem. A few months ago while driving, the STi started running on three cylinders. Sounded like a VW Beetle and was very rough. Could not see anything wrong, and it suddenly cleared up a few miles later.

No problems for a few weeks, then did it again. This time it would suddenly clear up for a few seconds and run fine and then start again. I tried stopping and restarting a few times but no difference. Again it suddenly went away.

After speaking with Paul from ZEN, as he had mapped the car, we guessed that it may have been a faulty coil pack. The next time it did it I connected the laptop and went for a drive. Fueling and everything was okay.

I then tried to isolate which cylinder was at fault. Whilst running on three cylinders, I loosened the four coilpacks and one by one I removed them. Obviously a good one, would make the car run on two cylinders. Worked out that the furthest from driver i.e. the one at the front on the passenger side made no difference. This was the one.

Had a look at the spark plugs and this one was wet with fuel while all others were fine. Put in a new set of plugs to make sure that the plug was not faulty. Swapped coilpacks and thought that the faulty one would make another cylinder run badly. But when I next started it, it ran fine and was okay for a few weeks. This was driving me nuts, Put it down to a loose connection.

Of course the problem suddenly returned. Got my hands on another coil and tried it. No difference. So have worked out that it was not the coil at fault. THought that maybe there was a wiring problem and the coil was not receiving any power, hence the different coils did not work. I again decided to try and pull the coilout again as it was running, but listen this time for the current. As i pulled it of the plug I could feel and hear the current trying to jump to the spark.

I am now thinking that I have a faulty injector, as when it runs badly, it goes through fuel at an unbelieivable rate and there is a strong fuel smell. It must have been intermittently sticking open, and is now always open and there is too much fuel and it is drowning the spark or it is dribbling the fuel in rather than spraying and again drowning tha spark.

Anyone had a similar problem or has any ideas? How can I tell if an injector is faulty, without sourcing another one to try?

Hiya,
you could try swapping the suspect injector to another cylinder. Clean the plugs and go for a drive. If the plug corresponding in that cylinder is fouled then you'll it's that injector, - or possibly just it's lower o-ring.

i had exactly the same problem but with front driver side cylinder.

if i unplugged the coilpack nothing happened so tested that and the plug for spark and all was good, which made me think fuel???

replaced the injector but still no joy. tested all the wiring and all was giving power??? :wonder:

then someone on this site advised me that my main realy (brown under driver foot well) could be faulty, so replaced the bad boy and i was back in business.

but i may add when my relay was faulty it threw up fault codes 24,44&45

Thanks for both your replies.

Might try the relay before swapping injectors. Much easier. I now recall that when we were tuning with Paul on the big boost setting and at full power, high rpm we could hear a buzzing noise from the relay box in the footwell. I checked the fuses all appeared okay. Wonder if this was a warning signal that a relay was faulty.

Where do the fault codes show? I have Autronic ECU so I imagine that the fault codes you refer to are from the standard ECU

yeah my cel was on and i checked the codes by connecting the connectors under the steering wheel. my car was not running right with this relay gone it was only boosting to 0.5bar

Hi, the main relay wont affect your injectors, or sparks, all it does is switch power on to some of the sensors on the engine, boost controller, idle airsolenoid and another solenoid, them being the fault codes that showed up. It also switches the power to the fuel pump relay, so i doubt it would be that.
If you think its the injector then go with that, i would be inclined to agree with you on it, you can test the mechanism by putting a voltage feed across the pins in the injector, i used 12v but that might be too much. If it clicks when you put the voltage across and clicks when you remove it then its woking ok, but like you say, its intermittent, and every few miles is a shed load of clicks!!! but try it and see if it fails to close, also check the 'O' ring for perishing and nicks, that could flood the cylinder. I would concentrate on the injector for now. What year and type of car is it??

Mike

Thanks, being tested tonight. Will try the injector and see what is going on.

It is a 2001 bugeye with a 2.5l conversion.

Okay checked everything. Not the coils, nor spark plugs, injectors or relay.

However did find out what has gone wrong. Upon starting up tonight, the idle started fluctuating. I was pissed off by now as i thought that it was a new problem. Decided to check the idle control valve on the inlet manifold. Noticed white smoke as well.

Unscrewed it and found that it was full of water:(

Those of you who know how these things work will know that it is operated by water temp and based on the water temp it opens/closes. The water should only enter one side. See picture below, the hose carries the water.

http://i141.photobucket.com/albums/r...0/IMG_0611.jpg

However the rubber gasket was split and looks like it has been ripped and tried to be repaired.

http://i141.photobucket.com/albums/r...0/IMG_0610.jpg

Water has been over flowing via the two sided by side inlets and down to the inlet manifold. The spark was being drowned by water not fuel!! Managed to connect a high powered vaccum and sucked a heap of water from the inlet manifold where it was sitting.

I do not know how much water has been injested over time and for how long and what damage has ocurred. Need to find the gasket now and see if it runs right. Change the oil as well and hope for the best

Everyone bear this one in mind as it could be an engine killer