Hey, I have a 2002 jaguar x type 3.0 V6 (left seat drive). I took it to the mechanic and he says that the ECU is not sending a signal to the second fuel injector. I have a few questions, if the ECU was bad, would it only target 1 injector? I feel like it would cause all 6 to misfire. The car is in limp mode and vibrates a lot, which I read are both caused by injectors. My last question is, how hard and expensive is it to replace the ECU? Thank you, any advice is appreciated!

 

Andis28, I would personally start with replacing the fuel injector harness before replacing the ECU. The fuel injector harness has a much higher failure rate than an ECU. It is also a lot cheaper to replace and fairly easy to do too. Can a single injector output fail in the ECU. Anything is possible. Can I say that I have seen it, no. BUt, I have seen lots of fuel injectors not working because of a bad harness.

 

Welcome to the forums Andis28,

I've moved your question from General Tech Help to X-Type forum. This is the place to post technical questions about your model.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Hi Andis28,

Each of your six injectors will be getting driven via a separate FET transistor within the ECU.
Thermo has given good advice, check injectors and harness continuity first.
Measure the resistance/impedance of your injectors so you can see if one deviates in readings from the other five. (you might choose to do that from the ECU end of the harness unless you already have good access to injectors with the manifold off currently).
If the harness good and injectors seem OK, then the ECU likely has one bad output.

Replacing the one failed FET might be a feasible option rather than the whole ECU, which will likely need programming to associate to all the other modules in the car and security system.
Compare ECU replacement and programming cost against a couple of hours for a electronics technician to find and replace the component (factoring in possible donor part and the back and forth to test part and reseal unit).
If you know someone who is good with component level electronic service, they should be able to crack the ECU open and measure the output devices to identify the problem one.
Sourcing a new FET might be OK depending on type, otherwise a donor board might be needed for suitable parts. If yo need a donor board then you might just fit whole donor ECU and get agent to reprogram to car.

However if a FET has gone it is pretty rare for them to die of their own accord. It likely failed due to a short in the harness or a injector coil that has some shorted turns.
So if you are happy the harness is OK, then I would also change the destination injector as a matter of course/safety to reduce the chance of the new FET from failing.

If the ECU is cracked open for repair, make sure they reseal it once it is verified as fixed, so it doesn't get any moisture finding its way in at a later stage.
Good luck.