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I got a "open in circuit 1" code the other day. I cleared it and it hasn't come back however it wouldn't surprise me if it did. Last night I checked the resistance of all 4 injectors. Number 1 was 13ohms and the other three were 13.2. Is the 0.2ohms difference within tolerance? I cant seem to find any info on the +/- acceptable variation.
I can hear the injector tapping - sounds the same as the others. Have tested power and switching to all injectors and they are all good.
The car had another MIL - running lean. I checked and found no vacuum leaks (with a smoke machine), the TMAP works as expected and hits the pretty much the same values as my focus (issue is with Ford Ka 2008)and when I hook up my laptop and read live data the pre cat O2 sensor will not go above 0.5v and likes to stay around 0.35 which indicates lean conditions. At WOT it goes down rather than up so that tells me there is a potential fuel issue as at WOT the voltage reading should flick up to around .8 or .9. Injectors all seem fine though, but its odd that I got the circuit issue as that would explain it.
New O2 sensor is coming today so I can rule out that the sensor is not playing stupid on me.
Any ideas on what to check??? Fuel pressure regulator?
Cheers
It should be fine, but resistance checks on injectors are useless in my experience for assessing injector performance Good for an open circuit or where one is massively different to all the rest. A scope is the best way to test them.
Was the code for the specific number 1 injector? Easy thing to do would be to swap injector to another cylinder and see if the code moves.
Sounds like you are on the ball and I hear good things about this:
Hth
Update - fitted new O2 sensor and it was working well, ie flicking btw high and low voltage as it should. Previous one did not do this at all. Old one looked very dead! However after running for a while it stopped flicking and went all the way down to 0.1 and stayed there!
P0200 code came up immediately as well - however before it was P0201 (injector 1), now its just the circuit in general - FFS. It was idling nicely and sounding really smooth and then it got a bit rough. Seems like it might be an intermittent electrical issue causing the problem. I'm thinking maybe bad ground somewhere - there is a lot of corrosion on the car so that could be possible. . Bad injection would explain the low voltage on O2 sensor as it would be running lean but it doesn't explain why the voltage stopped flicking between high and low! They all seem to run via two relays - fuel injection and fuel pump relay. Going to check the relays and the connections this afternoon