testing HELP

[magpie]

after having a head skim and new head gasket the car is now only running on 5 cylinders [m52] can someone tell me how you check if the injector is getting power ,it's number 6 that's down

I've swapped the injector from pot 6 into pot 1 and pot 1 is running fine and pot 6 isn't firing still .i've had the plug out of pot 6 and it has a spark [plugged into pot 6 coil pack] .



the wires are red/white and brown/pink in the pic .
below is what i've got to test the wires with .



what setting do i need the meter on and what should it read .

Tia,Mick.

[gromgsxr]

You should get 12v with ignition on but not running or 1 of the 2 wires to ground guessing it will be red wire, check both stick one probe on a wire and the second on sum in metal in the bay block or head ect.the ecu will turn the ground wire on to fire the fuel.

[magpie]

i put the live probe on the brown wire and earthed the red/white one and the probe wires got very hot very quickly so tried the other way round,live probe on red and black probe on brown with earth to strut top and the injector clicks with contact of the probe and i'm getting readings of 11.55 up to 11.88 on all 6 injectors.the readings are rising and falling on each injector when tested so there is no steady reading.

this isn't looking good

[Speedtouch]

The probe wires shouldn't get hot at all if you're on a voltage setting, as it is a high impedance input that draws very little current - are you sure you didn't have it on amps range?!

The injectors are pulsed, so a digital meter isn't going to show any meaningful readings - you should use either a test lamp or an analogue moving coil voltmeter, or an oscilloscope to show the pulses.

Use the multimeter to check that each injector plug has a good earth - use either resistance or continuity range and hold one lead against battery - or an earth point on the car and use the other probe to try each injector plug earth terminal.

[gromgsxr]

Sounds like they are all getting power then could try a test light or small bulb connected in place of the non working injector should flash / glow when you crank / run the engine.

[magpie]

all i have here is this to test with.



where do i put the red probe, middle or left hole and which setting do i put the meter at.

do i need to go get a test light screwdriver thing ?

[magpie]

all injectors are showing -12.40 when checking the earths.

[craigieeb]

Mick, knock up a simple test light, with a bulb and a couple of bits of wire

[jimbom30cab]

Mick, I had something similar , turned out I had bent one of the injector pins slightly so it wasn't making the connection when the plug was fitted

[magpie]

here's a vid of where i'm at ....

[youtube][/youtube]

even though the bulb isn't lighting up i can see/hear the engine loose revs via a power drain when i hook the probes up on all the injectors apart from number 6 where nothing happens at all.

[gromgsxr]

Have you got a wire pin out of what wire does what on the ecu? If so remove ecu and do a continuity test from the injector plug back to ecu, turn meter to HFE and probes in 2 on right if you touch probes together should beep that means electricity can flow though. Put 1 on the injector plug wire and the other on the wire at the ecu end if it beeps the wire works will be the non red wire on the plugs

[DanThe]

What Jimbo said Mick, pull the plug rail off and check the pins/sockets are all looking ok
You need an LED test light to show the injector pulses, a bulb cant light up fast enough

[magpie]

i'll have another look tomorrow ,i can't be far away from driving this now

[Speedtouch]

Use the red probe to the middle socket on the multimeter - the one to the left is for high current (10 Amps) testing only.

Don't bother with the hFE setting - that's for testing transistors, using the little yellow socket on the bottom right of the multimeter.

The bulb test might have worked, if you used a smaller, say 2.2 Watt dashboard backlight bulb instead of a 55 Watt halogen headlamp bulb!

[wellard]

The injectors are suplied 12volts on a common connection so if you have the same voltage at each injector that is okay.each injector is switched to earth via the dme.
As Dan said check the plug on the injector as the connectors can push out into the rubber cover when you plug them on.
If that is ok then check the brown wire from the injector back to the dme for continuity.you can download e36 wiring diagrams for free if you google them.
If the wires are ok you may have an internal fault in the dme.

[magpie]

i've just checked the plugs and they are all ok,i hooked up the dashboard bulb and it flashes on pot 6


gonna put the plug rail back on and try it again.

[pacerpete]

Shame it is not a quattroporte The fix would be much easier

[Speedtouch]

i've just checked the plugs and they are all ok,i hooked up the dashboard bulb and it flashes on pot 6

Repeat the test for the other injector sockets; all should flash in a similar way.

[magpie]

all the injectors are getting power,i've just checked again that i have spark on pot 6 and that's ok so i swapped injector out of pot 6 into pot 1 and started it up again,still running on 5 pots with number 6 down still ...why won't it fire up pot 6 .

could it be the timing ?

[DanThe]

Screwdriver stethoscope on the injector and you will hear it clicking if its working

[magpie]

all injectors are ticking away ,it's just running lumpy and if i unplug pot 6 coil pack it doesn't get worse


the plug would get wet if it wasn't firing wouldn't it ?

[Speedtouch]

Try a compression test.

[magpie]

i don't have anything to test it with ....

[craigieeb]

have you swapped the coil pack from no 6 to a different cylinder?
to see if that cylinder drops off?

[magpie]

have you swapped the coil pack from no 6 to a different cylinder?
to see if that cylinder drops off?

yes mate,swapped everything over.
injector,plug and coil pack .They all work on another cylinder .

if plug 6 wasn't firing it would get wet yeah ?

[craigieeb]

if plug 6 wasn't firing it would get wet yeah ?

Yep

[magpie]

think i need a compression tester it's not looking good

[Speedtouch]

Yes, it would. To check for compression, remove the spark plug for #6 cylinder and spin it over on the starter and either poke your finger or thumb over the plug hole if it will reach, or use something suitable such as the end of a bog brush to feel for the pressure.

You could even put your face over it to feel (and hear) for the draught.

[magpie]

i'm going to run the car in a bit for a short while maybe 5 mins and check if #6 plug is wet .
if it isn't then i'll whip the cover off and check the timing ,well i'll put the crank to tdc and check the two cam squares at the rear are sitting flush with the head .

[driftwood]

Was everything ok before having the head gasket done? Could a valve have been knocked? You need to do a compression test with all the plugs out and with full throttle. I presume you actually have a spark at the plug. Not sure if the ignition system can be damaged if the coil packs aren't grounded or disconnected completely. Check these 2 things before going any further.

[magpie]

right it's running on 6 pots but rough with a clank noise coming from the inlet cam on pot 6


plug 6 before running

and after below.


off to spend another £21 on a compression tester

[magpie]

the results are in...

pot 1


pot 2


pot 3


pot 4


pot 5


and finally pot 6



engine number two F00ked !

[Rtaylor2208]

Nightmare, this engine swap is getting mighty expensive.

[Speedtouch]

Bummer, but at least you now know the cause of the non-running cylinder, and those compression gauges can be used on any future engine you want to check, so are well worth having.

Maybe it has a bent valve?

[magpie]

so i take the head off and turn it upside down,make sure the cams have pot 6 valves closed and fill the valve bowl with water to see if any drains out ?