Ok so rough idle still and missing.

 

Things i have done.

 

Replaced coil plugs with new

Cleaned out Idle control valve

Replaced all coil packs

Replaced one injector as it was reading 18/20.ohms

Checked all vac hoses for leaks

Checked spark plugs (ok)

Checked battery / alternator (multimeter) 14.4 volts

Checked fuel pump plug connection

Checked all round engine bay plugs and replaced (fixed) loose or bad connections

Tested each injector with meter all now reading between 10 and 14 ohms

Checked coil pack plugs with meter.

Checked MAF stalls when unplugged

Although UN related 're set TPS

Checked codes 55 clear.

 

So far I'm up to about £300. With parts ect .

 

I can't do anymore as its beyond my knowledge if I took it to a local garage they'd scratch there heads and charge me time. So it need some one with knowledge of these engines . No doubt I will have to travel a fair distance (if she will make the journey)

 

Could this be a fuel.pump issue? That's the only part I've not tested is the fuel pressure or the fuel regulators ?..

Have you checked that the correct voltages are coming through the wiring loom to the injectors and coil packs?

Powerzed at Bristol is your best shot buddy.

Have you checked that the correct voltages are coming through the wiring loom to the injectors and coil packs?

Hiya zxtt I have checked the voltage of coil pack connections which are fine.. injector plugs no. I will tomorrow . Thank you

People seem to be preoccupied with checking voltage as a means of diagnosing electrical issues.

 

The voltage appearing on the multimeters for all intents & purposes may indicate all is OK, in reality it may not be correct.

Why?

Because the correct method of checking voltages for diagnostic purposes is to measure voltage drop through the circuit.

Voltage drop can only be measured when the circuit being tested is under load.

 

Measuring the resistance in ohms of a fuel injector or ignition coil will only indicate the integrity of the wiring in the coil.

The resistance values will vary in accordance with the temperature of the item under test.

 

It will not provide any indication of the serviceability of the injector in relation to cleanliness, flow rate or spray pattern, the only way to test these important aspects of a fuel injector are to remove it, have it cleaned & tested on a machine.

Also fuel injectors can be 'lazy' or slow in operation, ohms testing won't identify this problem, measuring amperage with a low current probe & a meter capable of graphing the readings will assist in identifying this type of fault.

 

The same deal with coil packs, once again the coil integrity is tested with the multimeter using ohms, the output of the coil can be compromised by poor connections to the spark plug, leading to carbon tracking to ground.

If this occurs the spark plug won't fire, or if it does it will certainly only operate intermittently.

 

Spark plug type, heat range & gap can also have an affect on engine performance.

 

The first thing to be checked in my book is engine compression, if engine compression is down, performance will be down & fuel usage will be up.

Also, if there is a dud cylinder, no amount of testing & changing out components is going to fix it.

 

Changing out parts as a means of diagnosing faults is a very poor method of rectifying problems & will turn out to be expensive in the long run.

 

If fuel pressure is a concern, then testing the pressure is mandatory.

Fuel pumps wear out eventually, that's a fact of life.

Fuel pump condition can be diagnosed using a low current probe & graphing capable multimeter by checking the current across the commutator segments.