Hey there,

Been lurking for a bit, finally need to run something by you guys. I have a 2004 XJ8 that I (used to) daily drive, (I would love to get back to driving it once I get this issue resolved!) But it went into like mode on the way in to work one day and when I got home to read the code being thrown, I saw P0207 - Injector Circuit Malfunction.

I changed the coil and sparkplug first since I was planning my tune up at 170k miles (166k right now), and of course the code stuck around, so today I took all of the fuel injectors out on cylinder 7s side.

Visually they all look acceptable, I marked my number 7 injector and started cleaning them with an old tooth brush on the outside.

I'm not a fuel injector pro, so here's where I would like some advice....

With my multimeter set to ohms at 200, by default it shows "1" when the terminals are not touching anything to close the loop.

Of the 4 injectors on that bank... Their readings were:

- 14.7
- 14.7
- 108.5 (cylinder 7)
- 1 (as if the loop is not closed)

So from looking at the above, it seems like the 14.7 readings are good and what we want. One injector had an extremely high reading, and the other doesn't seem to be closing the loop at all.

To me, this sounds like replacing two injectors are in order, the (1) and the (108.5).

The odd part to me, was that I only had a code for cylinder 7 misfire, which was the high resistance injector... when i have one injector that isn't even closing a loop. Unless I messed this one up as I pulled it off the fuel rail.

Let me know if this sounds like an accurate assessment of the situation. I'll be grabbing two injectors at this point to try and get my XJ8 back in action!

Cheers,
Dustin


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Hi Dustin,

I've recently had a similar problem with one of my injectors completely failing (open circuit failure). It read 1 OHMs and all my others read 14.7 or 14.8.

With the electrical connectors removed from the injectors and tested for OHMs, if you are getting a reading of 1 then that injector has definitely failed and needs to be replaced as it is open circuit. I would also replace the injector reading the high 108.5 value if that reading is correct. That is definitely also having a problem unless you have managed to touch your multimeter probes together whilst testing the OHMs as that would also give you a high reading like this number. You may want to double check and retest it again just to make sure. If you retest and you still get this high reading then definitely replace that injector as well.

Here is a good tip for refitting your injectors and the fuel rail.

Make sure you don't pinch the o-rings or you will get a fuel leak (even just a tiny one). I did this and it caused all sorts of problems - misfires, starting issue, stalling and fuel rail pressure sensor faults. I didn't have fuel leaking (no smell etc) but seems to have been either letting air into the fuel rail or letting fumes out. When you refit your fuel rail and injectors then try to use new o-rings for all your injectors and wipe the o-rings with a small amount of engine oil before refitting as that will help greatly in seating them correctly without fowling the o-rings.

Thanks,

Chris

 

Thank you Chris for the validation and the tip to be aware of the o-ring fragility. I noticed on some of the ones I pulled from that bank that the o-rings seemed fine until I removed them to clean the injector body, after which I saw a few hair-line cracks forming on the inside. I have no doubt these are the original injectors so I will be replacing all of the o-rings before installation for sure.

Thank you for taking the time to help me out!

Cheers,
Dustin

 

You're welcome Dustin.

Perished o-rings will appear with very fine cracks, and look dry as you have noticed yourself. New o-rings are quite cheap so worth replacing them all whilst you are in there. I purchased spares when I replaced my injector on cylinder 5 just in case any other others were perished or damaged during install.

You probably already know, but each injector needs two o-rings, one on the top and one on the bottom. They are different sizes as well so make sure you get the correct o-rings. I purchased an OEM injector which came prefitted with both o-rings a well but I got spares just in case. The injector I replaced also appeared to be the original at approx 137K miles. Glad I did as I split an o-ring one when refitting the rail and didn't notice as there was no fuel leak. Only found the split o-ring when I removed the rail to check.

I hope you get on ok and let us know how you get on.

Thanks,

Chris

 

Dustin. I can only say thanks for your assessment of whats going on in your engine. As I have a p0206/216 code your post is very relevant to my issue. My issue is with the 4.2sc engine in our 08 Range Rover but it’s this fab site that I now believe holds the key to my issue. I finally figured out how to release the left bank injector harness clip so i could then access the relevant injector pins. 3 gave me 11 ohms and 1 had infinite ohms (ie no reading on my ohmmeter)which I actually consider as being open circuit. I cannot access the connectors directly due to the poorly designed intercoolers that leave no space or wire length to pull them from the injectors. So failed injector #6 or failed wire(s) to #6. I thought that perhaps the wire had been possibly chewed but I really see no evidence of that ( from the tiny amount that I can see) so now thinking that #6 really has failed open circuit and it’s just a weird coincidence as to possible circumstances that lead to it going what I would call open circuit with infinite resistance. Any observations would be greatly appreciated as all data suggests about 10 hours to open and close this issue on the 4.2 sc and I am in my 71st year. Many thanks to all.