Hi Everyone,
I am a new member of the Forum but have been perusing topics here for some time as I try to sort out my XJS. Thanks to everyone for the plethora of information you have provided! Previously, I have never worked on a Jaguar and I don’t know how anyone could work on one without such information!
I found a 1983 XJS 5.3 HE which sat in an airplane hanger in Wyoming for many years. It is cosmetically pristine and has obviously been stored indoors its entire life and not driven in inclement weather. It was not running, so I towed it home.
After much preparation, I got the car running but it barely idles at 500 rpm and cannot accelerate even the slightest without stalling. Here is what I’ve done so far, but nothing improved how the car runs and I’m about out of ideas. Can anyone offer suggestions of what else I can do?
1983 Jaguar XJS 5.3 V12 47K miles
Battery:
Weak, charged then maintained with trickle-charger
Fluids:
Antifreeze, oil, oil filter and air filters look fresh, will wait to change them after engine is running properly
Fuel system:
Bad fuel, dirty tank and sump: several pounds of rust and varnish removed!
Drained and power washed both, new gasket on sump
Bad fuel sender and gasket replaced, tested, works
Replaced fuel neck o-ring
Plugged sump and main filters, replaced with standard main, aftermarket stainless-steel sump
Stuck, dirty fuel pump, freed, cleaned internal filter, pressure and flow tested
Dirty fuel system, applied 15” vacuum to pressure regulators and forced a quart of isopropyl alcohol at 40 psi through entire system from trunk back to trunk to clean it
Injectors cleaned by running injector cleaner through each on bench, verified pattern and flow. New filters, pintle caps, hoses and clamps installed, rail thoroughly cleaned
Ignition and electrical:
Replaced spark plugs, verified ignition wire firing order, tested ignition wires, all cylinders firing
Lucas ignition module looks new inside, didn’t replace HEI module, replaced crumbling connector and other connectors with glue/heatshrink crimp connectors
Checked, cleaned and tightened all GNDS in engine bay and trunk, but haven’t checked the one under the engine yet
Checked and cleaned all fuses in engine bay and under left and right dash
Throttle bodies:
Replaced throttle linkage end bushings, throttle body gaps were 0.002, adjusted throttle linkage, cleaned throttle bodies, gaskets looked good
Vacuum:
Full-load vacuum switch tested, vacuum hose replaced
Interior air controls line holds vacuum, interior controls not tested yet
Brake booster and hose hold vacuum
Vacuum solenoid wires disconnected, tested and reconnected them
Tested full throttle solenoid, throttle switches, vac solenoid, regulator, air control, vacuum dump, capsule, delay valve, manifold vacuum line holds vacuum
Replaced all emissions vacuum lines on A side and fuel regulators according to stickers on hood
Auto trans vacuum line holds vacuum
Cruise control and associated line hold vacuum
Engine prep before starting:
2 tsp of oil squirted into each cylinder while spark plugs were out, hand-cranked by front pulley nut clockwise to ensure engine was free and turned smoothly prior to starting
Startup:
Starter would not turn over and fuel pump would not run
Removed and tested main relay, fuel pump relay, starter relay, inhibit relay, replaced fuel pump relay anyway to ensure reliable operation.
Open connection found after inertia switch, suspect immobilizer somewhere behind radio (could not find anywhere else). Transmitter for it found under dash near right fuses, all magnetic door reed switches removed, installed fresh battery in transmitter and tested it, placed in glove box. With reed switches removed (Normally Open when doors are closed) the receiver should work properly but connection remained open
Bypassed inertia switch in engine bay by connecting coil 12V to inhibit relay pin 86, can easily revert to normal connection if open eventually found.
Fuel runs for two seconds when key in RUN and continuously when engine is running
Fuel pressure regulators both work and hold vacuum, rail pressure holds at 36 psi, pressure slowly drains when engine is off, maybe 4 psi per day.
Engine Idles at 500 rpm with 8” of vacuum, stalls when throttle opened, engine sounds tight, makes no strange noises and does not smoke, cannot hear any vacuum leaks, mixture seems lean
Exhaust flow feels smooth on both pipes when engine running
TPS:
Calibrated to 0.34V, wiper voltage increased smoothly through range to approx. 5V, however, did not have an analog meter to check for spikes
Ohmed TPS connections to ECU (each was about 1.2 ohms), measured between wiper and +5/GND at TPS and ECU, each was about 200 ohms higher at ECU than at TPS even after thoroughly cleaning the TPS connectors
Took the TPS that was on the car apart and the carbon was worn off for perhaps the first 1/3 of rotation. A second TPS looked very clean externally, like it was original. It calibrated easily to 0.32V but no change in engine operation
Replaced the TPS with new red version with adaptor. Had to finely file two holes to get it to fit. Calibrated to 0.32V via red and yellow wires, no change in engine operation
ECU:
DAC2597 6CU HE CEI 11.5:1 O2 Sensors Catalyst
A spare ECU in the trunk marked “Bad” works the same as the one currently installed. Opened that and it is in pristine condition with no evidence of burns, repairs, or bad solder connections.
Both ECUs hold vacuum, the vacuum line is clear and registers the same vacuum as at the engine
Found this firm that repairs ECUs, are they reputable?
ECU REPAIRS
Unit 3 Brookmarsh Industrial Estate
70 Norman Road, Greenwich
London, SE10 9QE
United Kingdom
If selected, I would send the ECU marked BAD to them as it is probably the original and like the rest of the car, is in nice cosmetic condition. They supposedly test, repair and retest to ensure robustness
A more reputable place from the Jaguar forums:
I emailed AJ6 but did not receive a response so far
Address:
AJ6 Engineering,
60, Henshall Road,
Bollington,
Macclesfield,
Cheshire
SK10 5DN,
England
Phone: 0044 (0)1625 573556 Text messages cannot be received on this number.
Business Hours: 9am – 6pm Mon Fri (GMT)
Email:roger@aj6engineering.co.uk
Additional items:
Activating the full-load switches to bypass ECU feedback did not make engine sound different
Cleaned gas cap gasket and adjusted both tabs so that the gasket seats evenly
Did not replace B-side charcoal canister lines, however, they looked fine
Did not test temperature vacuum valve as I thought it risky to remove
Could not find a charcoal canister purge-valve, looks like a direct connection?
Did not test supplementary air valve
Did not adjust the base fuel map
Red plastic plug with small cut found on B side air filter housing blocking Idle Air Valve intake, removal didn’t affect engine operation, may be indicative of sticking/stuck IAV?
Alternator has been replaced with GM version, overcharge lamp on dash is on but have not looked into this yet, could overvoltage have damaged the ECUs?
Did not test 45 second timer, could not hear a difference after 45 seconds of running
Have not checked timing and have not replaced the distributer guts, however, visual inspection looked clean and in good shape, verified all cylinders firing by connecting timing light to the coil ignition wire and watching light for misfires
Have not looked at pulses from the Lucas module to the ECU, did not verify all wires continuity to the ECU
Thanks in advance for any help you can provide and I apologize for anything I may have missed in other topics.
Sincerely,
Ken