It still sounds like you are having voltage problems. There are a couple of areas you need to check that will cause the loss of voltage you are seeing.

1. Check the bulkhead connector on the right hand side of the engine bay. The cable that comes from the battery in the boot is connected to the engine compartment at that location. It is know to corrode and cause high amp drains.

2. There is a ground cable mounted on the right side under frame. It is about 12 to 18 inches forward of the right front wheel. It connects the engine to frame. If it is original it will be a braided flat cable. Make sure it is clean of corrosion and the connections points are free of corrosion and tight.

Get back with the results.

 

If I just use a/c it is ok, but when I use def, then the RESTRICTED PERFORMANCE comes one with the amber light the car misfires. I think the engine uses more power for defrost. and it has oil going to the spark plugs causing it to misfire...

 

sounds good I shall try this out. Now #1 isnt that where the factory tool box plastic peice is and there is a little connector. Right?..

 

"DEF" is the front or rear defroster grid wires. They are very high
draw circuits. Nothing to do with oil, etc.

 

its the front. so it is electrical related. But why is it misfiring when I press def?

 

Check the voltage at the battery before and after switching AC and "def' on to see if there is excessive draw on charging system.

 

The bulkhead connector is located just forward of the area where the under bonnet tool bok area is located.
One side of the cable is the wire from the boot/trunk and the other side is the cable to the starter motor.

 

Because you have a power fault.

Whether it's cabling or battery or whatever.

The DEF is a huge power draw.

So you've a fault and the above results in inadequate remaining power for the coils to work properly thus misfires.

BTW, you're causing cat conv damage during this...

 

Thank you, this is the answer I needed of why it was misfiring. Ik about the unburned air and fuel going to the cat. Ok I should clean the terminals and check the voltage. Appreciate it.

 

Good luck! Let us know what you find. Someone else will have the same thing sooner or later.

 

Does your car have the heated front windscreen? -- it very rare in the USA. Although you have an early car ? I don't remember it being available when I ordered my 02. I had a 98 VDP -- did not have .

If you do have the heated screen -- and you are not just hitting the defrost on the ACC ... it's perplexing. Maybe the compressor is pulling too much?

The ACC is wired into the CAN through the Temp output of the instrument cluster -- so it is all interconnected. I think you should monitor the alternator output -- make sure that the volts are always up .. should be close to 14.

FYI -- restricted performance .. failsafe engine ... etc. When this occurs the engine goes into a mode that feels like it's misfiring. My point is -- the car may not be misfiring because of the defrost .. it maybe going into the that mode .. and you think it is misfiring.

When I had my problem last fall. Car would go into mode shortly after starting most times -- or after sitting it would run fine and then fail as I was coasting to a stop with the brake lights on. If I cleared the codes -- it ran fine ... then and only if the "restricted" would pop up .. did the engine shake.

 

I don't have the heated front windscreen. But ik it is not the compressor because I can just use a/c without DEF for hours and cold air blows. but when I do turn on DEF the Restricted Performance warning comes on and the engine misfires shaking the whole car.

 

The fan does go to high on defrost --- what happens when the fan speed is increased to high in auto mode with the temp set low enough for the compressor to be running?

 

@yeldogt everything works auto and a/c but when I turn on DEF with A/C ONLY restricted performance and misfires

 

Yes .. I understand. When you hit the defrost button -- The flaps change and the fan goes to high. I can't see the flaps causing any issues .. but the fan ... being electric .. maybe.

It's very strange -- must be doing something.

Obviously the rear defroster and the front (that you do not have) -- pull a lot of amps .. so that's more understandable. I guess it's possible that the fan is pulling too many amps -- would think the control would be affected.

I would have never believed my battery would have been able to start the car -- but still be the cause of my problem. And I.... have owned three of these cars -- two bought new .. so I have a long history around them.

 

appreciate the help, im going to replace the valve cover gasket and spark plugs seals, ill buy them from rockauto and install them and put a new ignition coil for #7 as I have the lifetime warranty and well go from there...

 

Have you checked the voltage?

If the engine runs correctly -- it's not the plug seals -- and I don't see it being a coil with your description.

 

Yeah, that is also what I think you should do, clean up the other problems and issues you have first, and slowly zero-in on this one.
Often, while doing so, you will stumble on something which might help solving the big one.

Besides, from reading this and some other threads of you, I think you should be ready to try to do some measurements, either with a simple multi meter, or through an app like Torque.
Tracking things like voltage will give a much better understanding of what might be going on, for you, but also for us .

 

Thank you! I will do this and check the voltage soon.

 

One more thing to test the circulation fan- set the heat to max temp. which should set the fan on high. Obviously if the fan is the problem you will know.