Switching two cylinder running

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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 12:43 pm

I had dvm on 200 ohms, & there was no reading across the 2 pins, it said on "Autovista" tec data, I should have 0.25 to 1.5 ohms, there is no reading across the pins. I also have checked other siemens injectors & they are the same no reading? am I just on the wrong scale? Terry
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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 12:44 pm

Sorry also if the injector was faulty why is it changing 2 at a time, runs on 2 then changes to a different 2 ??
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Re: Switching two cylinder running

Postby KimAndersen » Mon Mar 07, 2016 12:48 pm

Yes - your on the wrong scale and that's why you're not getting any readings on your DMM :wink:
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Re: Switching two cylinder running

Postby volrem » Mon Mar 07, 2016 4:54 pm

Terry Ferguson wrote:I had dvm on 200 ohms, & there was no reading across the 2 pins, it said on "Autovista" tec data, I should have 0.25 to 1.5 ohms, there is no reading across the pins. I also have checked other siemens injectors & they are the same no reading? am I just on the wrong scale? Terry


Piezo injectors don't have low resistance like solenoid ones. You are on the wrong scale. Go up in scale until you get a reading.

Also check that you have no continuity between injector pins and injector body. Measure in Megaohm range.

I would still like to see if engine starts with 4 injectors and then cuts 2 or is really starts with 2.
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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 5:03 pm

I have measured them on the 20 M range & im getting 0.18 on them all , I will check the Earth on this range as well, also the loom from injectors to Ecu , I am waiting of original Ecu being returned ( tomorrow I hope) thanks for help, terry
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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 5:13 pm

I'm pretty sure it starts on 2 then stays on them, knock it of & come back to start it & it starts just same, but if you unplug injectors, it's now off on the other 2 cylinders, so it runs away with 2 injectors unplugged & has still never ran on all 4 at any time? It has harsh knock, that is quieter if you manually open egr , as you unplug things, this causes a code, but if you clear codes, you can start & stop it & no codes are logged, so it seems to think nothing is wrong??
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Re: Switching two cylinder running

Postby volrem » Mon Mar 07, 2016 6:30 pm

Terry Ferguson wrote:I have measured them on the 20 M range & im getting 0.18 on them all , I will check the Earth on this range as well, also the loom from injectors to Ecu , I am waiting of original Ecu being returned ( tomorrow I hope) thanks for help, terry


0,18 in 20M range means 180kohm and this should be in spec.

Measuring cables resistance doesn't prove that it's OK since voltag drop occurs only under load (current).

If your DMM has this function the measure injector capacitance also.

Terry Ferguson wrote:I'm pretty sure it starts on 2 then stays on them,


Only way to prove it is to measure it. Cam, crank and two injectors from different pairs (1 and 2 or 3 and 4). If you can get all 4 injectors into clamp somewhere in loom then it would be great. But ypu havet gent only 1 wire from each injector and that is difficult since these two wires are twisted.

Have you checked powers and grounds with scope under load (engine running)?
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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 6:48 pm

I only have 2 low amp clamps, I can put them on any injector I have good access to loom at ecu, I have break out leads etc, I could back prob all four would that be worth while, obviously there would be no cam & crank in this instance, Or is it better to clamp 2 injectors & Keep cam & Crank? terry
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Re: Switching two cylinder running

Postby volrem » Mon Mar 07, 2016 8:12 pm

Crank is needed (to see injection timing and changes in engine speed), cam optional. At least two injectors needed.

If you can run all four wires (one from each injector) through one current clamp then it would be good. Or two injectors through one clamp ant other two through another clamp.

If not then one clamp for one injector.
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Re: Switching two cylinder running

Postby Terry Ferguson » Mon Mar 07, 2016 8:35 pm

I can get 1 wire from all 4 injectors in one clamp i think, Can certainly get 2 in one clamp & other 2 in the other clamp, If I get 4 in one clamp & b is on Crank, what are we getting from this, whats the advantage of 4 injectors in 1 clamp? I assumed each injector would be monitered better individually? This is all good stuff for me to learn! I am hoping the ECU is Here tomorrow then I can run these tests, While I'm on I would like to ask another question about Picoscope, I have an old car in here now I suspect Condenser as its Back firing, But my question is I plan to use the Probe MI074 on the plug leads, Do I need to use an Attenuator with this lead, The instructions are very vague, It looks like it has one built in, I plan to put one on coil lead & other on number 1 plug lead as reference, dose this sound correct? Thanks Terry
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