Can noid lights be used on an M62?
 

I asked this same question in my rough-running-engine-post-valve-cover-replacement thread, but I thought I'd start a separate thread on this specific question to open the question to a broader audience: Has anyone ever used noid lights, or any similar technique, to troubleshoot whether the DME is sending a signal to the injectors? I'm getting an open injector circuit error code for cylinders 7 and 8 on my 03 4.4i. My concern is that noid lights are typically attached to one injector connector at a time, and the engine is started, running on one less injector than normal during the test. But since the injector connectors in the M62 V8 are all connected together via the injector control box, I don't know of any way to disconnect one at a time. So, when you crank the engine, it's going to try to run on just one bank of cylinders. So, can the noid light method still be used? If not, is there another way to test the DME signal to the injector connectors? Thanks.

There should be one connector for each injector you would disconnect at the injector and insert the noid light. I think you are confusing the control box with the injector.

Yes, there is one connector for each injector, but each bank of connectors is effectively held together on the control box, so I can't remove them individually, unless I figure out how to remove the connectors from the control box. Maybe something I should look at...

The other option might be to open the rear of the control box to expose the wires, figure out which wires go to which connector, insert a pin into the appropriate wire to make electrical contact, and connect the leads to a bulb. Any idea as to the injector control voltage? I'd neded this to figure out what size bulb to use.

I have not used a noid light, but agree that trying to run the engine with one whole bank disconnected could stress it. This problem lead me to think the same approach as doing a compression test would be appropriate.

I am assuming you are prepared and capable of clearing and resulting codes from this procedure - from the other thread it sounds like you have the gear.

Start by pulling the fuse for the fuel pump and then start the engine and let the engine run until it dies without fuel. This should remove fuel from the system and keep you from dumping extra fuel into the oil if you crank it without starting. You can then pull the control box off the whole bank of injectors, hook up the noid light to whichever one you want and watch it as someone cranks the engine over. Typical behavior would be some stronger pulses during cranking followed by some more rapid but weaker pulses. I am not sure the pattern matters to you, as you just want to see if the injector is getting a signal to fire.

David,

Yes, I do have a code reader.

Your idea sounds like it's worth a try. Just one things bugs me - the local auto parts store only sells noid lights in a backage of about 8, for brands I don't own, and I don't want to spend $30 for what's basically a light bulb I'd probably only use once in my life. So, do you (or anyone else) have any idea what wattage bulb I could use as a substitute for an actual noid light? I tried using a 21W tail light bulb on a known good connector, and it didn't light up. Anybody have a guess as to how much current (I erroneously said voltage in my most recent post) the injector signal puts out? The 21W bulb draws over 1.5 amps, which I should have realized is way too much. Thanks.

I haven't seen the spec, but I will assume the signal is 12 V. The coil is nominally 15 ohms, so 0.8 Amps, or 10 watts on a 12 V circuit. I think the actual signal is pulse width modulated not amplitude modulated, but you should see the thing blinking.

This sort of test light would work fine, too, just has to be held in place.

Amazon.com: ATD Tools 5513 Heavy-Duty Circuit Tester: Automotive

Hers's the exact wording and sequence of the codes that come up:

1. P0208 Injector circuit open cylinder 8
2. P0207 Injector circuit open cylinder 7
3. P0363 Misfire detected fueling disabled
4. P1357 Misfire cylinder 8 with fuel cut-off
5. P1355 Misfire cylinder 7 with fuel cut-off

Does it sound like a problem in the injector circuits in cylinders 7 and 8 is causing the misfire, or that there's a misfire being caused by something else (like a bad coil for example), which is causing the DME to cut off the signal to the injectors?

Wish I could answer that. Those descriptions are the same as what appears in the Bentley Manual. I don't have any other source to go to.

Did you try switching the two ignition coils with other cylinders to see if the failure moved around? Its another quick and free test...

You can remove the connectors from the box.