My 2001 focus is only firing on 3 cylinders. Cylinder 1 is at fault. I've replaced the coil pack, all leads and plugs but problem still persists. Could it be a blocked injector or something more serious?

Turn ignition off, press and hold the mileage trip reset button, and turn ignition on so red lights show, keep trip button pressed in, untill the word test shows up on milaeage display, let go of button, the dials do a full sweep press again all bulbs on display light up and just keep pressing untill DTC shows up and let go it will then show a dtc code write it down, then press button again and see if it shows any more.

Full instructions.

Some of the different Functions

Functions

1 Gage Test
2 Dial Test
3 Bulb Test
4 Diagnostic Check
5 Diagnostic Check
6 Clock Type (shows ?date 44? if UK)
7 Diagnostic Check
8 Speed MPH
9 Speed KPH
10 Revs
11 Fuel
12 Engine Type
13 Temp of Engine
14 Battery Voltage
15 Diagnostic Check
16 LCD Display



Diagnostic Check (18-30)

Pretty easy really!

1) With the ignition switched off press and hold the trip computer reset button.

2) Switch the ignition on.

3) Release the reset button

4) The above will be displayed with each press of the button.

5) To exit this mode switch the key off. When you switch it back on again the dash will return to normal.

You can look up dtc codes here Clicky here and here.

Done exactly what you said, then this flashed.. dtc - none.

Are you getting a spark trying various plugs .. I would of gone with coil packs for sure

All plugs and leads are firing. New coil, new leads and new plugs. ?? :-/

Would it be worth getting some redex, flush my injectors?

This is how I cleaned my injectors, [youtube]7aT4S1lIBAY[/youtube] and I noticed a big difference.

take injector leads off and on 1 by 1 and you should hear the engine change note slightly, if it doesn't change on a certain injector, thats your faulty one.

Do it with engine running.

Ste - thats only useful for finding where the problem is, I think he mentioned it was No1...?

If thats the case, try moving an injector between pots and see if the fault moves with the injector.

I took the plug out of 1 but made it worse. So don't think its injecter. So if its not injecter and plugs, what next?

What engine is it ?

If the coil pack did go, some times when the coil packs fail they can damage the output circuit within the ECU itself.

Also check the inlet manifold gasket for air leaks using carb cleaner or similar.

its a 2.0 petrol, forgot to mention is also converted to lpg

Get some carb cleaner, and with engine running spray it around inlet manifold and clean the mass airflow sensor on air intake, but you can never really clean these properly, but as a temp measure clean with electrical contact cleaner.

I have funny feeling it will be air leak somewhere (if you have ruled out plugs leads and coil pack) and carb cleaner should find it.

Now then .. does it run ok on gas try switchin from one to the other .. we may be able to rule out the injector

Exactly the same on both..

It won`t be the injector then since gas (fairly sure)is piped into the inlet manifold .. I would`nt like to speculate any further mate but maybe worth getting a proper diagnosnic done on it .. If it was me I would`nt run it anymore until then .. good luck anyway.

It runs fine when driving but idles like a bitch, loud vibrates and scoffs the fuel.. Had it on computer, said cylinder 1 and o2 sensor. Fixed o2 sensor..

Idleing rough. Clean idle control valve

also change the pcv valve

Done it

Get some carb cleaner and spray around inlet manifold, and any where else air pipes are, failing that, send mrhanky a pm.

TPS issue, but only when its in the idle position...?

You have tried quite a few things and seem fairly competent with the solutions you are trying. If you are continuing to try this DIY, maybe get the emissions checked and see what the car is doing fueling wise at idle - rich or lean. From your symptoms Id suggest rich.

If the fault goes under load, then like you have already said this points to an O2 sensor - which you have changed. Has the car been code read since you changed the sensor? The issue may be a poor connection in the loom.

TBH this sounds like and electrical sensor problem, its just finding the issue on these newer cars...

Idle control valve, if sticking will reduce the air to the engine at tickover, and will give a slow idle, it shouldnt drop a pot and run rich if the idle control valve is at fault.