two injectors not working

[kodachromeII]

Hello all, earlier this year my maestro was playing up, turned out to be an injector. Car has been perfect until two weeks ago when i ventured out in heavy rain and driving thru mini rivers!! up to the sump. Now the car is intermittenly miss firing once its up to temperature, mechanic has narrowed things down to two injectors possibly not working, though no voltage test has been carried out at the injectors ( the two nearest the air flow meter ). All leads, plugs, arm cap are new. Any ideas what can possibly cause intermitten missing on two injectors? One of the two injectors was replaced with a brand new and the fault remains..... PLEASE HELP :banghead:

Cheers
Andy

[G Force]

. Any ideas what can possibly cause intermitten missing on two injectors? One of the two injectors was replaced with a brand new and the fault remains..... PLEASE HELP :banghead:

Cheers
Andy

Hello Andy.

The only things that can cause 2 out of the 4 injectors to intermittantly fail is the injectors themselves or faults in the injector wiring in the local area of the injectors.

All the injectors are fired at the same time, being powered and earthed on the same two wiring connections at the EFI ECU. A wiring fault would have to be in the loom near the injectors where each individual injector wire branches out from the main feed and earth wires.

If your mechanics diagnosis is correct then as you renewed one injector with no change you must have a fault in the wiring as described above.

Do you notice any fluctuation of the rev counter needle when the fault occurs?

[kodachromeII]

when the fault occurs, the car stalls unless i keep the revs up, the revs are fluctuating. Seems the fault only occurs after 15-20 mins, once the engine is warm..

[mgdavid]

when the fault occurs, the car stalls unless i keep the revs up, the revs are fluctuating. Seems the fault only occurs after 15-20 mins, once the engine is warm..

doesn't sound like wiring...

[kodachromeII]

wiring to injectors all checked, no corrosion at all. When mechanic checked the car, plugs were sparking, disconnecting the injectors made no difference to the tick over, which at the time the car was only firing on two. Could problem be a weak spark, iffy coil? Cap and arm were swapped out in May 2010, leads and plugs this week...Odd that it only fires on two once up to temperature..

[G Force]

Could problem be a weak spark, iffy coil? Cap and arm were swapped out in May 2010, leads and plugs this week...Odd that it only fires on two once up to temperature..

You would not get a situation where the coil would produce a poor spark on only two cylinders.

Disconnnecting the injectors at tickover only proves cylinders 3&4 are misfiring, not that they are faulty, the fault could still be electrical, ignition, or mechanical.

Even though the cap and rotor arm have been replaced I would check here first. Has the cap been removed since you ran through the water? Check for moisture, cracks inside/outside the cap.

You can test the rotor arm when hot by removing the cap then holding the king lead (with insulated pliers) 10mm away from the rotor arm centre whilst someone cranks the engine. You should not get any sparking from the end of the king lead to the rotor arm. If you do the rotor arm is faulty.

[kodachromeII]

Swapping out the cap later today. The plastic mounting plate between cap and block has a peice broken off, although never an issue before could this be a problem? Cap has been twice thoroughly checked for dampness since the problem started. Any idea where i can find a new/used mounting plate, part no. NJF10002?
Cheers....