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Hi guys need some help please. I have a 2003 citroen picasso 1.8 and when it gets warm the engine fail light comes on and he car starts losing power (especially up hills) and then stalls at halts. I narrowed the problem down to a fuel injector failing when warm so i changed that, it didnt help. I used a diagnostic tool and its telling me theres an Injector circuit open, what i thought then as there was a break in the wire somewhere. I have carried out a continuity check (using Ohms as my multimeter has no continuity setting) and i checked each fuel injector wire from the injector clip right up to the ECU attachments and couldnt find a break in any of the wires as each one is registering the exact same amount of Ohms…….im totally confused as to what it can be?? Am i doing the check wrong or am i looking at a failed ECU? Thanksin advance for any help as im just banging my head against a wall at the minute lol
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What you should try is a voltage drop test. The currents in the injector circuit are so small that a continuity test isn’t valid. An Oscilloscope would be much better suited to this task, but a quality digital multi meter would suffice (Fluke model 73/77 or 87), the leads must be in excellent condition and good quality as well.
Identify the positive (+ve) and negative (-ve) side of the injector at the harness and ECU. Check +ve voltage at the ECU WRT (with respect to) ground, then check +ve voltage at the fuel injectors WRT ground. Then, check the opposite side of the injector WRT -ve (positive lead on the battery positive post, negative lead at the injector). If the values are the same when tested at the ECU as well as at the injector, the circuit is good. If not, the circuit is failing when hot – perhaps corrosion in a connector?
If possible, find out what voltage should be at the injectors and check to see if it is low during the fault. Again, corrosion is possible, but its plausible that a transistor (the ‘driver’ for the injector) will function perfectly when cold and yet start to fail/breakdown when there’s heat in circuit – IE failing ECU. You should also consider supply voltage and grounding to the ECU as well.
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