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The dealer changed the regulator when the car was 3 years old in an attempt to fix the problem. I have the original.
Just a pain to get to the items.
But I’ll have a look next weekend thanks.
to totally rule out the regulator… do a throttle snap test. With the engine running, snap the throttle to full wide open then let off. What are the readings… at idle, then wide open then back to idle.
Andy
I believe you have checked the pressure regulator and fuel pump and should be satisfied that they are working properly. the purge valve if leaking can allow gas fumes to be pulled into the intake and cause a rich condition and idle problems. check the purge valve. no air should pass in the closed position. best way to check would to be to remove the valve and try and pass air through the valve. you do not want any air to pass.
You mean at the tank end?
The UK cars don’t have one there. It’s open after the charcoal canister.
If you look in my other post there is a diagram layout linked.
Ok… I have gone back and re read all your posts on this… we have ruled out the fuel system and EVAP as being the problem.
On to the EGR… the EGR will cause a rich condition as it is introducing hot exhaust gases into the intake, the PCM will note the extra oxygen via the 02 and start adding fuel. With the EGR open even a little, idle will be off and get better at higher RPM.
You had mentioned that you blocked off the EGR and the trims went positive (2%) and when a hold developed in the block off plate, the trims went back negative. But in blocking off the EGR you get a P0400.
Lets get into the EGR. If you have not already done, clean the EGR seat and pentel. Check the pentel spring, it should hold the pentel in the closed position firmly (you should not be able to move it by hand). Try and pass air through the passage way, no air should pass. If the EGR is Ok, install it on the car. With the engine running, disconnect the vacuum line(plug off the vacuum line so it does not leak) and apply vacuum manually. Idle should be smooth then get rough as you apply vacuum. Check trims with EGR in closed position your trims should go positive like when you had it blocked off. Re attach the engine vacuum line, note any idle change.
Does your Jag have a supercharger?
if the EGR turns out to be the problem and after you make the repair and your trims come back to normal range but you still get a P0400 (EGR problem)… I have read that a bad or failing supercharger actuator can cause a P0400 code to trip.
Ok thanks.
I only got a P0400 when I blanked the EGR (insufficient flow, so it was correct)
I will take a look at the SC bypass when checking the EGR (as its not far from the EGR)
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