Hi guys.

Long time no see!

My XJR has been relatively well behaved the last year or so, but now a new fault has appeared. Basically the car IS idling a bit higher than normal. This puts the car into the standard limp mode, and gives me a code for the MAF and also P1611, which is a new one to me. Switching of ignition for a few seconds clears the codes, but they come right back in seconds/minutes at best.

Replaced the MAF with a known good unit, made no difference.

Battery is only about 3 months old (Yuasa 019).

Any ideas are very much appreciated!

Screenshot of codes attached

 

Another thing that may be relevant:

When I start the car, the RPM counter sits at zero for about 1 or 2 seconds before moving to where it should be.

Very strange.

 

Quiet in here these days 😢

 

Normally a chatty group here, but I don't think anyone has a simple answer to your question.

Does the car require a longer than normal cranking time to start the engine?
If so, you might have a crank position sensor fault.

P1611 error has very little commentary on it here. The X100 forum had someone diving into it, but that thread is like reading a long book with the last few pages torn out of it.

The rev counter delayed reading could be a valid clue that there is something going on with the data communications between ECM and cluster or the ECM missing an external input and taking a while to extrapolate engine activity via other inputs.
Do you have any other instrument cluster oddities...no odometer reading etc?

Earthing points are always the starting point with any fault in these cars........check you cabin earths, the ECU earth behind shock tower and the earths behind the headlights.

The high idle would normally indicate that the engine is being over fueled as intake air leaks would normally under fuel the engine.
Perhaps you have high fuel rail pressure with a bad FPS or the air bleed spigot on that unit has broken off.
You might want to check if it is running abnormally rich.

 

I just googled P1611 and got this:

That code means that the communications link between the automatic transmission computer (EGS in BMWspeak) and the engine computer (DME) is missing.3 Mar 2019

A fault in the gearbox electronic connector is well known due to
trans fluid leaking on to the connector.
You have gearbox codes also so that fits it seems to me.

 

False. P1611 does NOT mean that in a Jaguar.

 

Thanks for the tips.

Watched a few videos and the rev counter thing actually seems to be quite normal, strangely.

Fuel trims are all fine, became an expert on those a few years ago when I had a very mysterious vac leak.

When the idle is high, I can see the throttle is open on the Torque app. But I'm not sure if that's reading the actual throttle position on the throttle body, or if it's reading the pedal itself. If it's not the pedal then something is causing the throttle to open thus causing the high idle.

Wouldn't high/incorrect fuel pressure rhrow a code of its own?

 

Yes you could expect codes, but I'm wondering if the pressure sensor itself is sending incorrect information to the ECU which in turn is altering the drive on the fuel pump, then everything else downstream could be trying to compensate in one way or other and remain within operational window.

Might also pay to check your TPS in case it has a bit of a dead spot. My X-type had some poor tracking just off idle, changed the TPS and the flat spot resolved.

I also wouldn't rule out the mechatronic sleeve causing comms errors, our transmission is used in a lot of other models, so if a P1611 code as Merion mentions is featured n the BMW codes, it might pay to consider the possibility.

 

Cheers, will check this out in the morning.

I do keep getting fault codes for the MAF all the time.
What could that be? It's not the MAF sensor but could it be something else?

 

looks like p1911 is a throttle target malfunction, that may explain the high rpm idle.

 

This is what the powertrain section of the Jaguar service manual has on P1611, probably not very helpful but all that I could find;


P1611 ECM sub CPU failure ECM failureContact dealer technical support
for advice on possible ECM failure.

 

I think the P1611 is a symptom rather than the cause.

I have been really busy with work all week but am gonna get a proper look at everything today.

Would connecting to SDD help? I hate using it as its so clunky, but it does give tons of data. If so, where on SDD would I look for clues?

 

I'd be more concerned about the P0783 code frankly.

P1611 = ECM (Central Malfunction; Sub Processor) - throttle target calculation [throttle target calculation vs. ECM Processor value]

 

Nah, I've got a plan for that.

 

On the torque app I can see when the trottle is at 0% then idling is normal. When this issue occurs the throttle is round about 3% without me touching the pedal.

So why would the throttle be opening by itself?

Fuel trims are fine so there's no vac leaks...

 

What I don't understand is that all these faults have their own specific DTC, so why aren't they showing? I mean if the TPS was dying it should have its own DTC. The pedal position sensor has 4 wipers so if it was dying it would have its own DTC too. Anybody any ideas? The P1611 doesn't occur when driving hard, only when the car returns to idle.

 

Did you ever check the transmission connector for leaks? It will start giving odd readings because CAN buss is compromised and ECM com can be lost/intermittent.

 

How do I access that? Any other places I should look too? Thanks.

 

The throttle body stepper motor is going nuts when I turn the ignition on. I am very reluctant to use any kind of cleaner on the throttle body.

What do you reckon?

Tried to upload a video but this site can't handle .Mp4 files apparently.

 

The connector is on the right side near rear of the transmission - is accessed from underneath car. You may see oil running down from it or you may have to take it out if it has only just started to leak.