Been having a lot of fun trying to get the wife's Ford Puma Millennium to run today. We were out and about in it yesterday (looking for new cars ironically) when it started misfiring, progressively getting worse as we drove around. We stopped into a Halfords to see if I could diagnose the problem and fix it cheaply. Removing the HT leads one by one revealed the problem to be with cylinder number 1 (removing any other HT lead made the car idle even worse). A new set of plugs didn't sort it and neither did a new set of leads so we limped it home and I've been working on it today.

I have swapped the following items one at a time and tested them on my 2.0 litre Focus, which I know runs absolutely spot on before I start swapping stuff.

Coilpack - Focus runs fine, Puma still runs on 3
HT leads - Focus runs fine, Puma runs on 3
Spark Plugs - Focus runs fine, Puma still on 3 cylinders.

So I have now completely swapped all the ignition system and proved that the coilpack, HT leads and plugs that were in the Puma are all absolutely fine but the Puma still has a problem because the Focus coilpack, HT leads and spark plugs are all known to be good.

Then I borrow a compression tester, thinking cylinder 1 is dead, which reveals strong compression (150psi) on all 4 cylinders. I then remove injector number 1 and swap it for injector number 3 - the car still runs on 3 cylinders so it's not a fuel problem and removing HT lead 1 doesn't change how the engine runs, removing HT lead 3 takes the car down to 2 cylinders.

I am now completely at a loss as to what the heck is going on. I have changed the coilpack, HT leads and spark plugs so it's not an ignition problem, I have ruled out a fuel issue by swapping the injector and its not a compression problem either. MAF, ISCV, TPS and Lambda sensors have all been changed for new items within the last 12 months. The only thing I have noticed is that when removing HT leads 2,3 or 4 the car runs like a bag of nails, when I remove HT lead 1 the engine runs exactly the same but I am getting electric shocks through the lead as I am holding it. This may be a red herring, especially as I've tried 3 HT leads so it's not the lead itself that's the problem.

ANY help on where to go from here is most appreciated.

 

is the cylinder 1 getting injector pulse?
Test using a noid light or a 501 capless bulb with the pins bent and pushed into the injector plug

 

Brilliant idea, will have a go at that tomorrow.

I still suspect it's an ignition issue but I've changed everything for working stuff...............though I can't work out why I get 'bitten' when I remove the lead off the plug!!!

 

Sounds like no fuel getting into cylinder 1 could be a wiring fault to injector 1?

 

Did you try disconnecting the wiring plug from injector one to see if it ran any different, like you tried removing HT lead one and it didnt run any different?

 

do any of your mates have a scope or a dvm ? if so check input to injector 1 - you can use a dvm in conjuction with a small capasitor and compair it to one of the other cyminders - they should all be the same as they should all let in the same amount of fuel - it could be a bst conection in which case wd40 might help by removing any water in the connectors!

 

Have you tried the puma coil pack and leads on the focus just so you know for certain they are ok.This sounfs like a very wierd fault.

 

focus and puma coilpacks are different part numbers iirc there are 5 different coilpack numbers, however it should still work if only temporary for testing purposes i know you say you checked compression, however last time i had this fault on a puma it was a burnt valve tip

 

I have tried all of the Puma ignition parts on the Focus and the Focus runs absolutely perfectly, likewise I now have all the perfectly working Focus ignition parts in the Puma. Every part was swapped 1 for 1 and tested before changing the next item.

The only problem I have with checking the wiring to the injectors is the whole lot comes off in a single block, you don't appear to be able to (easily) disconnect one injector on its own. I have a video on my phone illustrating the problem which I'm trying to upload somewhere useful to illustrate the problems.

 

Create a youtube account my friend, quick and easy to do. They are very good guys on here and i only initially joined about a single problem but i have stayed active on here since discovering the wealth of knowledge!

 

Could be a cam sensor but could fueling.

 

If you disconnected all of the injectors, just put a noid light into the no.1 injector plug and give the engine a crank. It will still light up if everything is good.

If you're getting a spark on cylinder 1, the compression is ok and you've swapped the injectors over too then it suggests either you've lost the live or the ecu switched earth to no.1 injector.

 

Just swapping injectors won't prove anything if the fault is with the feed (fuel or power) to the injector as nothing will change. You need to make sure the injector is getting power and that it's actually injecting fuel before you rule it out.