[Mk2] [Turbo] Running on 3 cylinders - suggestions please?

[pugwash]

Hi guys, looking for a bit of help. Have searched about but no one seems to have exactly the same symptoms.

1991 Rev 2 Turbo, 75k on the clock, suddenly started running on three cylinders while driving gently. Plugs, leads, dizzy, coil, rotor were all changed a couple of months ago and there is a good spark at the end of each lead so have discounted spark.

Started looking at fuel: Resistances are the same across the injector resistor pins and earth, changed for known good anyway to make sure, no improvement.

After checking plugs, #4 didn't smell of fuel so changed injector for known good, still the same. Injectora are all being supplied with 12ish volts.

My next step is going to be cranking with injectors out to make sure they are firing, but is there anything else obvious I'm missing?!

Cheers for any advice.

Si.

[bobhatton]

Hi guys, looking for a bit of help. Have searched about but no one seems to have exactly the same symptoms.

1991 Rev 2 Turbo, 75k on the clock, suddenly started running on three cylinders while driving gently. Plugs, leads, dizzy, coil, rotor were all changed a couple of months ago and there is a good spark at the end of each lead so have discounted spark.

Started looking at fuel: Resistances are the same across the injector resistor pins and earth, changed for known good anyway to make sure, no improvement.

After checking plugs, #4 didn't smell of fuel so changed injector for known good, still the same. Injectora are all being supplied with 12ish volts.

My next step is going to be cranking with injectors out to make sure they are firing, but is there anything else obvious I'm missing?!

Cheers for any advice.

Si.

What does the plug look like on the cylinder that is not firing?

[pugwash]

heers for the reply. Car is on the garage so will have a look first thing tomorrow. Think all the plugs looked the same though.

[kev8611]

Place the end of a long screwdriver on each of the injectors and put your ear to the other end. Should hear the injectors "tapping" as they fire.

Or unplug one at a time and see if the engine note changes.

If all seems fine. Compression/leak down test

[pugwash]

Did alll the above and worked out that injectors were only firing on startup when they all fire, compression was good.

Neglected to mention that the car has LPG and I think that this is the issue. There is a module which shuts down the petrol injectors when the LPG kicks in and I think it has gone haywire.

Thanks for help with eliminating other possibilities!

Cheers

Si.