Good afternoon everyone, I'm Ross the proud 3rd owner of my 1991 3.2. Having a couple of issues I could use some advice on please. 1st is a missfire with backfire once warm and over 2k revs. I've replaced the ignition side, plugs, leads, dizzy cap, rotor arm, coil & ignition amplifier, but can't do timing as ecu controls it? I put it in local garage today & they have the same conclusion. I've been told to replace the crank sensor & would like your advise please.
2nd issue is rear suspension has dropped on one side, again my local garage has said hydraulic issues but I'd again like your advice please. Many thanks.

 

Have the garage or you do a compression test on the engine when warm to determine a basic condition of the cylinders and valves.

As far as the suspension drop, does your car still have the self leveling suspension or has it been converted to regular coil springs as most were back in the day?

 

Hi Ross,

Welcome to the Jaguar Forums! It's great to have you with us!

One thing you could do is to check the Vehicle Condition Monitor for any stored Diagnostic Trouble Codes. To do so, turn the key to position II (ON) but do not start the engine. Press and release the VCM button on the trip computer to the right of the steering wheel and watch the odometer/mileage display window below the speedometer for a message to appear. DTCs appear in the form of FF or Fuel Fail and a two-digit number, such as FF24 or Fuel Fault 68. Write down any code you receive and post it here and we'll try to help.

Problems with the crankshaft position sensor (CPS) won't trigger a DTC, but some issues with other systems will, such as fuel delivery, O2 sensor, etc.

Another thing to check is your coolant temperature sensor (CTS). If it fails at a cold resistance or the wiring harness breaks, the engine control module (ECM) will continue to apply cold-start fuel enrichment even after the engine has reached full operating temperature, leading to rich running.

Also check the fuel pressure regulator (FPR) by pulling the vacuum hose off and inspecting for wet fuel at the vacuum fitting, which indicates failure of the diaphragm, which allows raw, unmetered fuel to be inhaled into the intake manifold, also leading to rich running.

Another possibility is cracks in the air intake plumbing pipes or crankcase breather hoses causing lean running.

Cheers,

Don

 

Thank you for the info, I've got Fuel 47 & fail 47 showing. Regards Ross

 

Hi Ross,

The diagnostic manual at the link below is for the 4.0L cars, but it should also be applicable to your 3.2L. See the diagnostic flowchart for FF47:

Jaguar AJ6 4.0L Engine Management System / OBDI Diagnostic Guide S-91

If the diagnostics indicate your Idle Air Control Valve stepper motor has failed, it is possible that an inexpensive part from a Renault Megane may fit your car. It fit our '93. See the photo album I did on this at the link in my signature (sorry if the large images aren't working, but the thumbnails and descriptions may be helpful).

Cheers,

Don