Well after going away and fitting two new maf sensors and still getting engine light on, went and done another inspection. Low and behold found this, a crack in the passanger air box. It is located right below where the inlet pipe begins, as you can see from one of the pictures the mesh protecting the sensor can be seen. Car did get a previous small bang low down on that side which i was aware of, non structural , which must have done the damage. I got an air line and put in up against the crack and the air is blasting through. The Maf sensor during live data was showing fluctuations in reading compared to the other side. Dealer is ordering a new air box so hopefully this is the end of it

 

congratulations t finding the plausible cause. Cross my thumbs that its okay afterwards.

 

Thanks, it's under warranty so that's a good thing, think the box is around the £300.00, off topic did you see my thread on new paddle shifters fitted with pictures, any comment welcome good or bad.

 

Good detective work! I'm glad they're not fixing it with chewing gum or duct tape!

 

Is the thought process here that additional air is being introduced into the airbox up stream from the filter and then changing the sensor reading causing a MIL? This would make the sensor very sensitive . Also putting compressed air to the crack would show more of a leak vs just plain air under driving conditions. I hope this is the fix but I am a little skeptical at this point. Good luck.

 

jagtoes, i hope this is the problem. The other side is perfect, 2 new sensors and 2 new jaguar dealer filters. the OK side shows good readings during the live data. The crack being before it hits the sensor would be letting in more air or out. As i said the side with the crack seems erratic. I'm presuming when i accelerate the car takes in air some is either coming in through the crack or pushed out, hence the readings. All i can do is try it, anyway i would say that the crack isn't doing any good for air intake.

 

Some of the old tricks still apply.

You can watch the short term fuel trims and spray a little MAF cleaner on the cracked area. If air is leaking in, you will see the trims go crazy.

It is a good find, fingers crossed that your problem is solved.

 

I hope so and agree that the crack needs to be fixed. I guess where my thoughts are is the MAF changes voltage to the ECU depending on air flow and temp. I don't know how the ECU treats the 2 sensors because I would suspect they would always have 2 different values. There is a range that they work in and when one or both go out of this range it triggers the MIL. They should compensate for the difference in air flow but maybe higher flow triggers the MIL. This would mean if one air filter gets dirtier then the other it may trigger a MIL. Also I don't know if each MAF feeds a separate bank of cylinders or is combined in the SC chamber. As i said I hope it is the fix and if so then I will get a better understanding of the sensitivity of the air filters.

 

was talking to a guy who mentioned the egr valve but i rang a few dealer and they said the never had a problem with the egr valves on these car and can't even recall selling one.

 

I've read that having different type/brand of air filters or having one new one and one old one can cause fault codes, so if that's true then I'd say the MAF system is pretty sensitive.

 

yes 8bit i agree, mine have 2 dealer jaguar filters and 2 new maf sensor. Car isn't going to dealer till end of next week or following week. Today i viewed crack again and got some gorilla tape and sealed the crack from the outside, just to see would it make any difference. Erased engine light so will see if it comes back on. My wife has taken it for a drive today so will see is it on later this evening. Still getting erratic idle, rpm needle moving up and down when idle from 500-1000 rpm. Sometimes it goes below 500 and it feels as if it is going to die then picks up again. The car has had new plugs fitted around 800 miles or so, fuel consumption and when driving is ok.
I'm kind of losing my patience on the matter.
Just worried i would be damaging something driving around with this issue, do you or anyone think it is OK to drive with this issue.

 

It make you wonder why some car makers use 2 MAF sensors and others use only one. I was looking at a new Camero last night with the LSR SC engine at 580 HP and it only had 1.

 

yes one would be better, id'have less of a headache

 

It is unlikely that a small-ish air leak will cause any permenantly damage. If you can monitor the short term fuel trims just check that they aren't pegged at +/- 25%. If you see them somewhere in the middle, then the car is able to adapt to the extra air and no big deal.

I'd wager your idle problem is that the leak is a larger portion of the total air the engine is consuming at low rpm and load. Once you get moving the leak is washed out by the larger overall airflow so the car runs fine at speed.

And I can't say as I understand the dual MAF thing either. Far as I know, the two MAFs go through two tubes to a single plenum and single throttle body. What's even more bizzare is that on the x100 the 4.2L only had one MAF and one tube.

 

Re. your idle issue - you said you'd had the plugs changed, have you had the coils changed as well?

 

no just the plugs, didn't know i had too change them as well, mechanic said plugs were bad but coils were ok.

 

I have usually found that a "hunting" idle in the range that the OP has stated is indicative of an air /vacuum leak in the intake system. This would fool the sensors and change the idle. The basic function of the MAF is to work with the 02 sensors and ECU to adjust pulses of the injectors to attain the optimum fuel/air ratio. At least that is the short definition. I would think the MAF could adjust for the crack in the intake box without setting a code. Did they try a smoke test to see if there are any leaks in the emission system.

 

yes exhaust system is ok no leaks, did as i say put tape on outside of air box and after erasing light it has not come back on yet, so will have to see. rough idle is only when starting and sometimes when i come to an abrupt stop, but not all the time .

 

Well after a free week or so my engine light came on again with the MAF code. Still have air box crack taped up so it must be another problem. I think i am going to give up on it, will let it run and run, could be anything.
Off topic , i am entering a 3 day cannon ball run here in Ireland with around 150 cars taking part. All proceeds to the make a wish foundation Ireland a good cause. As i have never done this before ,it should be good fun and a chance to cruise with some fine motors.
Cannonball Ireland

 

Probably not taped 100%