Mechanics

ROUGH RUNNING

1986 Jaguar XJS

Engine Performance problem
1986 Jaguar XJS V12 Two Wheel Drive Automatic 93000 miles

Hello,
I have a 1986 Jaguar XJS V12. Vin Number: SAJNV584XGC130468. 2 Door Coup. This is the first time using this site. I deposited $45.00 as good faith that I want help in solving this problem.

Problem: The vehicle runs rich, the engine is erratic at idle, no acceleration, and black smoke comes out both tail pipes. The engine will stall after a few minutes. If the fuel pump relay is removed, the engine smoothes out until the fuel runs out. The car was to other mechanics that apparently were not capable to assess and correct the problem. They may have created additional problems. We cannot take anything for granted and must do our own diagnosis and tests.

INITIAL INSPECTION:
BATTERY: Battery was dead in car. Recharged battery.
OIL: The oil was contaminated with gasoline. The dipstick measured approximately eight inches above the fill level. We drained the oil and approximately fifteen quarts of fluid went into the drain bucket. The oil was very thin because it was mixed with gasoline. We changed the oil, installed a new oil filter, eleven quarts of oil, and one bottle Engine Restore.
AIR FILTERS: We replaced both air filters with STP air filters.
GASOLINE: The gasoline was old and smelled like varnish. We pumped out the old gasoline, flushed the fuel lines from the engine back to where the fuel filter is with compressed air and changed the fuel filter. We added one bottle of Techtron fuel conditioner and four ounces of fuel stable.
ENGINE: The engine has leaves, debris and surface dirt. The injector clips are missing. Found loose wires. Brake fluid is low. The spark plugs were fouled. Bolt missing on duel throttle actuator.

Tests:
Timing: was set at 18 Degrees BTDC but could not get 2000 RPMS.
Plugs: set at.025 gap. Champion Plugs RC9YC
Coils: Main and Auxiliary coils produced 12 volts.
Coolant Temperature Sensor: Replaced
Air Temperature Sensor: Passed ohms test – 800 ohms
Throttle switches (2) have been replaced






ENGINE Action
Detail engine Done
Replace hood struts. Done
Replace brake fluid. Done
Replace power steering fluid. Done
Replace coolant.
Replace thermostat gaskets Done
Oil and filter change: STP 2995 Done
Replace air filters: 2 Done
Replace fuel filter: FF761 Done
Replace belts: 4 Done
Replace thermostats: 2 Done
Made new fuel injector clips. “Paper Clips” Done
Replace Throttle Kick down switch Done
Replace Throttle Micro Switch Done
Repair Detent Cable Done
Replace spark plugs: Champion RC9YC: #344 “.025 gap.” Done
Replace Inlet fuel pressure regulator Done
Replace outlet fuel pressure regulator Done
Check distributor cap and rotor condition. Done
Check distributor position to No 1 Cylinder. Done
Clean Oxygen Sensors Done
Check Distributor timing mark Done
Check Spark Plug wire position on Cap Done
Check Distributor Cap and Rotor Done
Clean internal injection rail Done
Replace ignition module: DR100 Done
Clean, detail, and polish engine and compartment Done
Clean PCV valve and breather element Done

Compression test. Done
Front Wet Test
1B 150 1A 155
2B 100 130 2A 155
3B 150 3A 160
4B 130 185 4A 160
5B 130 185 5A 150
6B 135 160 6A 160

Fuel injectors: Resistance, Noid light, and Leak down test Done
Fuel pressure at Fuel Filter is 40 Lbs.
Fuel pressure at rail is 38Lbs.
We removed the fuel rail and connected the fuel lines and did not see any fuel leakage from any of the injectors.
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Caveman2649
May 21, 2009.



Whats with the A and B on the compression tests? For thetests to vary so much- up to 35 psi on one cylinder. The other was only 100 psi, then it was 130 then 150.......... do a dry comp test then a wet one.You may also need to do aleak down test to see if it has a bad intake valve or two. Have you done anything with the MAP sensor? Also remove the electircal connector off each of the injectors and do an ohm check to see if any of the injectors are shorted. Follow this link for more info

http://www.2carpros.com/first_things/excessive_smoke.htm

please let me know how it goes.
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Tiny
Jack42
May 21, 2009.
Hello, The A and B are the sides that the cylinders are on. A is the passenger side and B is the drivers side. We have not done anything with the MAP sensor. I believe it is inside the Computer located in the trunk? The vehicle was sitting for quite a while. We can do another compression test since it has been running. First time using this site. I also sent you an email before I noticed this response box.
Thanks. Bob

Tiny
Caveman2649
May 21, 2009.
Have you checked the injectors?

2CarPros Ken
May 21, 2009.
Hello, We reemoved the injector rail and connected the fuel delivery lines. We turned the ignition key to on and there were no fuel leaks. We did a resistance test and a noid light test. All injectors had uniform readings.

Tiny
Caveman2649
May 21, 2009.
Hi
Pull the fuel line off cold start injector attach pressure gague there. Start up what is reading?

Docfixit
May 21, 2009.
Try disconnecting the coolant sensor and 02 sensors. Let me know.

2CarPros Ken
May 21, 2009.
Hello, We will disconnect the coolant temperature sensor and oxygen sensors and get back to you. We do not see any cold start injectors. We only see the 12 injectors. Six injectors on each side. Thanks. Bob.

Tiny
Caveman2649
May 21, 2009.
In center of engine up front maybe buried follow fuel line to it. Also has wire terminal

Docfixit
May 21, 2009.
May 22, 2009

We did the compression test again.
Cylinder Dry Wet
1A Passenger 150 170
2A 150 170
3A 150 170
4A 135 170
5A 130 140
6A 140 145
1B Driver 155 160
2B 155 175
3B 160 180
4B 160 200
5B 160 240
6B 160 220

We have a new coolant temperature sensor and auxiliary air valve. The smog pump seized up. We will have a new one installed next week. We will then check the vacuum at the computer for the MAP sensor. We will also try disconnecting the Oxygen sensors to see if it makes a difference. We still cannot locate the cold start injector. We followed the fuel line from the passenger side regulator, through the injector rail, and out the driver’s side regulator. Both regulators are new. The auxiliary air valve has been replaced by one of the other service centers. Have a happy holiday. Bob.

Tiny
Caveman2649
May 22, 2009.
COLD START SYSTEM TEST CAUTION: This test results in fuel vapor being present in engine compartment. All necessary precautions against fire or explosion should be taken. Remove 2 set screws and washers retaining cold start injectors in intake manifold. Remove the start injectors and place them in a container to collect sprayed fuel. Disconnect distributor lead from the coil. Engine Temperature Below 59 °F (15 °C) Turn ignition switch "ON" and check the cold start injectors for any leakage. Crank the engine for a few revolutions. Injectors should spray while engine cranks. Do not operate the starter any longer than necessary. 1. If injectors do not spray, crank engine and check for battery voltage at cold start injector supply (White/Pink) cable. If voltage is present, check ground connections and wiring harness connectors at cold start injectors. Repair as necessary. If no defects are found, injectors are faulty and must be replaced. 2. Crank engine and check for battery voltage at terminal 87 of cold start relay. If voltage is present, check wiring harness between relay and cold start injectors and repair as necessary. 3. Crank engine and check for battery voltage at terminal 30 of cold start relay. If no voltage is present, check supply wire from pump relay and repair as necessary. If voltage is present, relay is not being energized or contacts are faulty. 4. Crank engine and check for battery voltage at terminal 86 of cold start relay. If voltage is present, relay is not being energized or contacts are faulty. If no voltage, repair the supply wire from starter circuit. 5. Crank engine and check for battery voltage at terminal 85 of cold start relay. If voltage is present and relay is not energizing, there is a problem with thermotime switch circuit. Disconnect wiring harness from terminal 85 and jump terminal 85 to ground. Relay should now energize. If not, relay is faulty and must be replaced. 6. If relay energizes, check for battery voltage at terminal 87 of cold start relay. If no voltage is present at terminal 87, the contacts of relay are faulty and the relay must be replaced. Reinstall the cold start injectors and all cables or connectors. 7. Engine Temperature Above 59 °F (15 °C) Crank engine and check voltage at terminal 87 of cold start relay. Voltage should be 0 volts. If battery voltage is present, remove wiring harness connector from terminal 85 of the cold start relay. 1. If voltage is 0 volts, the thermotime switch is at fault and must be replaced. If battery voltage is still present at terminal 87 after disconnecting terminal 85, the replace the cold start relay. 2. If cold start injectors pass fuel when no voltage is present at terminal 87, the injectors must be replaced. 3. Page 1 of 1 FUEL INJECTION SYSTEM - LUCAS/BOSCH "P" -1986 Jaguar XJ-S 5/30/2009
FUEL PUMP RELAY TEST Turn ignition switch "ON". The fuel pump should run for 1-2 seconds and then stop. If pump does not run, or does not stop, continue testing. 1. Check that inertia switch cut-out button is pressed in. Remove inertia switch cover and attaching screws and check to see that the wiring harness connection is secure. Remove wiring harness connector from switch and check for continuity across switch terminals. 2. Pull out button on inertia switch, and check for an open circuit across switch terminals. Reconnect wiring harness connector and replace switch cover. Reset inertia switch button. 3. If inertia switch operates to specifications, ground terminal 85 of fuel pump relay and turn ignition switch "ON". Check for battery voltage at terminal 86 of main relay. If battery voltage is not present, check battery supply from ignition switch via inertia switch. 4. Check for battery voltage at terminal 87 of main relay. If no voltage is present, check for battery voltage across terminal 85 and ground connection of main relay. If voltage is now present, replace main relay. 5. Check for battery voltage at terminal 86 of pump relay. If no voltage is present, check for an open circuit between terminal 87 of main relay and terminal 86 of pump relay and correct as necessary. 6. Check for battery voltage at terminal 87 of pump relay. If no voltage is present, check for battery voltage across terminal 85 of pump relay and ground lead. If voltage is now present, replace pump relay. 7. Check for battery voltage at terminal 30 on both relays and at fuel pump positive terminal. If no voltage exists, check for an open circuit between terminal 87 of pump relay and positive terminal of pump and correct as necessary. 8. If pump still does not operate, check ground connections or replace pump. 9. Page 1 of 1 FUEL INJECTION SYSTEM - LUCAS/BOSCH "P" -1986 Jaguar XJ-S 5/30/2009


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Merlin2021
May 30, 2009.
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