but were afraid to ask: Hi all it's a newbie again. My 1990 xjs v12 is stalling at red lights when I try to go, it will idle throughout the red light but when it turns green and I hit the gas it stalls. I restart it and drive away but I've read a few horror storys about the ignition system that makes me want to park it till I can find out whats wrong. It really does it when it is hot and ac on.It also stutters when in neutral at idle and you rev it. If I'mleaving anything out I apologize,I haven't owned a v12 before and am just trying to figure it out without ending up with a huge fireball.
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stalling
- Thread starter jarrod
- Start date
John S Farrington
Jedi Warrior
Offline
I recommend that you renew the spark plugs, spark plug wire set and distributor cap and rotor. While you are doing this, look for any potential vacuum leaks or gas leaks in the plumbing on top. Use only an original equipment distributor cap and rotor from Marelli. They should be medium blue in color.
jessebogan
Jedi Knight
Offline
Marelli caps are black, and the rotors are white.
You really need to get the repair CD from JDHT. You need to check the engine set up. Both throttle blades need to be set to .002 inches. Both throttle link rods need to be adjusted so that the throttle plates open exactly when the center splindle begins to turn, and at exactly the same time. Check the linkage bushings near the throttle plates. They are plastic, and when they break up it throws off the synchronization. You need to check the voltage at the throttle potentiometer. If I remember correctly at idle it should bebetween .32 and .36 volts. The voltage should rise smoothly as the throttle is opened to about 5 volts. When you replace the spark plugs, set the gaps as indicated on the sticker under the hood. Also, there is a micro switch at the left hand throttle linkage. When the throttle is closed, it should trip the switch with an audible click. It should open as the throttle is opened. this controls the idle timing map, and is important for both idle, and smooth transition as the gas is pushed. Hope this helps you to get started
You really need to get the repair CD from JDHT. You need to check the engine set up. Both throttle blades need to be set to .002 inches. Both throttle link rods need to be adjusted so that the throttle plates open exactly when the center splindle begins to turn, and at exactly the same time. Check the linkage bushings near the throttle plates. They are plastic, and when they break up it throws off the synchronization. You need to check the voltage at the throttle potentiometer. If I remember correctly at idle it should bebetween .32 and .36 volts. The voltage should rise smoothly as the throttle is opened to about 5 volts. When you replace the spark plugs, set the gaps as indicated on the sticker under the hood. Also, there is a micro switch at the left hand throttle linkage. When the throttle is closed, it should trip the switch with an audible click. It should open as the throttle is opened. this controls the idle timing map, and is important for both idle, and smooth transition as the gas is pushed. Hope this helps you to get started
I'm kind of nervous about doing the tuneup myself. I'm used to working on american cars and it seems that I'll be pulling alot of delicate equipment off of the motor to even get to spark plugs. Does the cd you spoke of give you a step by step or would I be better off paying the extra cash(of which I don't have very much) to have a garage do it? Basically what I'm asking is can a backyard mechanic do the work with the right manuals or should I just go to the import garage? This car is a toy (or a mistress as my wife looks at it} but I'd like to do as much of the work as I can but I don't want to hurt her. Thanks again to everyone.Your knowledge and input and willingness to help is absolutely invaluable.
jessebogan
Jedi Knight
Offline
You can do everything on this car. It may take some learning, and it will take some patience, but it is just a car. FWIW, I HATE working on FWD cadillacs with a passion, but the jag, while time consuming, is not too bad. I don't know if I am breaking the rules here, but you can go to jag-lovers.org, and download the "Book" by kirby Palm, and that is more "Owner" oriented than the CD, but both are likely required.
John S Farrington
Jedi Warrior
Offline
You have instructions on the ignition firing order (A bank is passengers side, right, and B bank is left. Follow it closely and take your time. Swapping the plugs wires and distributor cap/rotor is simple and straight forward. If your wires are now correct, that serves as a guide. The only difficult part of the spark plug tune up is getting access to the front two plugs because of the close fit with the air conditioner compressor. You will probably be able to change the plugs by just loosening up the mounts for the compressor. You dont have to unhook or remove it. Jesse was right the Marrelli cap is black. The older pre-Marrelli caps are blue. Give the vacuum lines and fuel lines close inspection while rewiring the plugs. Do the spark plug operation first and see what the results are. The butterfly valve/throttle pot adjustment is not required often, particularly on the V12.