Poor idle, AC issues, probably vacuum problems (1982 XJ6)

Hello I have a really ruff idle I have a 1982 Jaguar xj6 and the idle is rough to the point where it can just shut off i don’t know what’s wrong also when the engine is cold the car struggles to hit 20 mph and black smoke pours out of the exhaust I’m having a lot of trouble with the ac as well due to the vent flaps not opening does anyone know if this is a vacuum issue ?

Black smoke indicates that it is running way to rich on the fuel. Have you done anything that may have upset the fuel injection,(I am assuming its the 4.2)

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I’m no expert on the 6-banger, but if the EFI is anything like the V12 I’d be looking at the coolant temperature sensor for the EFI.

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Symptoms seem to discount that as it sounds as though it’s over fuelling when cold, I would have expected the CTS to give that when hot?

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The temperature gauge is accurate it stays in the middle sometimes goes over over sometimes stays little bit under what is the radiator plugged into? Because right now it’s not plugged into anything what is the green cable?

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What is the actual hot idle rpms, Josiah? The xk ‘uneven idle’ is a byword with a wide range of possibilities - first step is a compression test to eliminate the engine itself as a factor. Then there is uneven injectors, misfiring plugs (for whatever reasons) - even crossed plug wires, ignition timing…etc…etc…

If this happens only when the engine is cold and during acceleration, it’s typical, and easily remedied - check ‘cap mod’ in Archives…

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Check servo action: With the car warmed up; set ‘Auto’ and set temp control alternatively to ‘65’ then ‘85’ and listen. You should hear the servo ‘buzzing’ indicating that AC amp is resetting the servo. No servo action implies a defective AC amp.

If the defrosters are open at all settings; it implies loss of vacuum - to be pursued. Defroster should only be open in ‘Def’ setting - they are held closed by vacuum in other positions. But a malfunctioning AC might require some deeper checks…

Frank
xj6 85 Sov Europe (UK/NZ)

Hello my blower motors are acting weird sometimes they blue crazy strong and loud at the same time and the AC is perfect but most of the time there pretty weak like there operating at 75% not the 100 % they should be.

My guess is maybe it’s the fuse ? Or a relay

Someone from my apartment said it could be a voltage regulator relay maybe the fans aren’t getting enough juice ? Either way it’s really annoying and my AC isn’t blowing great. Any ideas or recommendations.

Set to ‘Auto’, Josiah; the fan speeds drops to low when cabin temp is at set temp - and is at high to reach set temp.

Set manually to ‘Hi’ the fans should run constantly at high speed; set to ‘Lo’ equally constant low speed. Except for ‘no fan’; fans should be tested in manual…so,?

Frank
xj6 85 Sov Europe (UK/NZ)

Hello my blower motors have been pretty inconsistent for a while they where very very weak now I found out if you put it in low for a second then go right to high they come out very very strong ! And it stayed like that for a good while. now the strong setting (high) is like like a middle ground setting not as strong as they used to be. I’ve tried to go back to low then high doesn’t have the same effect anymore. Both blowers are for sure working. My only guess is it could be a battery issue? As my voltage meter always sits under just a bit maybe the fans are not getting enough juice ? can anyone help me ?

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Not a likely issue, Josiah - best guess is bad connections at the fuse holder. Which will, as a rough test, be very, very hot - preliminary to a final break…

Frank
xj6 85 Sov Europe (UK/NZ)
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The whole fuse holder ? Or just the holder for the single 50V fuse ? Can I just change the fuse ? Or is there like a relay

Hello my AC randomly goes into heat mode I have a 1982 Jaguar xj6 series 3. It runs cold then out of nowhere goes quite then switches to heating mode then nothing gets it back to cold until it decides to go back on it’s own. Seems to have a mind of its own anyone know what’s wrong ?

Typical for a malfunctioning AC amplifier, Josiah - see other posts…

Frank
xj6 85 Sov Europe (UK/NZ)

Hello I am having trouble with my ac. none of the vent flaps open not even a bit, there just completely off ! I had to open all of them manually I don’t know where to start if not if the vacuum flaps work is it a fuse ? Or something else

Do you have vacuum anywhere and did you know the AC only comes on when the engine is warming up?
What do you mean manually

I just pulled the flaps open and I used stuff to hold it open I don’t own a vacuum or even know where to put the vacuum if I owned it I really don’t know where to start I have a 1982 series 3

Okay. In the engine bay there is a very thin rubber line coming off the intake manifold. I had a right hand drive so mine was different and I can’t tell you where it goes into the cabin, but there is an one way valve, and it will go to the cabin. Check if this is hooked up.

Then remove the right hand panel with the vent for the air which is brittle. Two screws, take the vent off and slide the panel forward. Remove just one vacuum line and don’t mess them up. Start the engine. Do you have vacuum?

The defrost vents are normally open all the time when you have a leak or no vacuum. You can see them through the windscreen. Rest is closed in that case.

I have a left hand drive the vents on the defrost are stuck up and the vents at the bottom for the recycled air is closed as well as the main center vent. So from the intake manifold there is a main line ?