Well, I've mailed Jeff about this, but I'm reluctant to *keep* bothering him with foolish newbie questions when I might as well ask them here ;)

 

My NA Zed is running on five cylinders - when this first happened the cat overheat light came on for a bit, but after easing off it disappeared, and while limping home up the M1 I only saw it once more. The engine smoothed out by the end of the journey, was fine the next day, but since then has been running on five constantly. ECU diag gives code 55. Oh, it might also be worth mentioning that I've been running *very* rich recently.

 

From a search, and from Jeff's advice, it's a dodgy connector or spark plug somewhere, right? OK, well I tried disconnecting what I assume are the coilpack connectors, one by one, and the dodgy cylinder is the middle one on the left (looking from the front into the engine bay). This is where my mechanical aptitude runs out and the stupid questions flood in:

 

Coilpack connectors: They're the chunky grey and black plastic connectors on each cylinder, right? I hope I've got this right :S The contacts look clean and shiny, and the connectors themselves are well pushed together. Is that all I'm looking for here?

 

Injector connectors: I'm loathe to investigate these because they're buried under the central cover, and because they have those little wires clips I am no good with. Am I right to think that it shouldn't be these, because of the cat overheat warning? I've not seen the warning light since, but then I've only trundled to the supermarket, taking it very easy - should it be appearing even then, or do I have to boot it to get this effect?

 

PTU: This was replaced a few months back, but it's possible the connections are a bit ropey. Again, I'm loathe to take things off to get to it unless it's a likely suspect. I kinda prodded the rubbers round the connectors with the engine running, and I got a dip in revs, as if I'd lost a cylinder - is this normal? Or could it mean I have a screwy connection and it just happens that only one cylinder is down *so far*?

 

Spark plugs: OK, where *are* these? :confused: In a flash of inspiration I undid the chunky thing next to the coilpack connector (held on by two 12mm bolts), but that didn't free anything, and I couldn't see what else to undo, so I put it back.

 

So, many thanks for any advice you can give. Please remember I am a technical moron, and any explanation or advice should be accompanied by fool-proof instructions on how to identify the relevant part. Sorry to be such a drag :/

If all else fails I'll limp onto the motorway and call out recovery to drag me to Jeff's, but it seems a little extreme for just a spark plug...

I seem to be having similar probs. Can I ask though...what is a PTU and where is it??

I'm a bit green around the gills with anything under the bonnet. Any response would be greatly appreciated.

 

Ian

I seem to be having similar probs. Can I ask though...what is a PTU and where is it??

I'm a bit green around the gills with anything under the bonnet. Any response would be greatly appreciated.

 

Ian

 

blimey talk about digging up old threads!

number 5 in the picture (driver's side front)

Its the square unit, bolted to the left cam cover as you are looking at it from the front, the only way to test it is really to plug a spare in and see if it makes any difference.

 

Before any of that though, I would recommend checking the injector plugs, make sure they are making a good electrical contact, and are not corroded inside.