Greetings all,

ah, the joys of XJR ownership.
I bought my Manual XJR, and on day 5 it was in the shop, not idling, and stalling at traffic lights.
It has a reprogrammed ECU which wont communicate with my mechanic's PDU (the correct Jaguar gear). It is complicated - the reprogramming software was sent from UK to NZ and loaded on a 3.2 ECU, then tuned at another establishment.
The car seemed OK for a day or two but was very thirsrty (I thought this was probably normal), then it was running irregularly at part throttle at low revs (eg pulling gently from about 1600 rpm).
Anyway, it would idle fine when cold but within a mile when warming up, it was in trouble.
My mechanic has so far diagnosed

1 ox sensor - not working at all
2nd ox sensor giving wrong readings
LNA1620AA airflow meter sending wrong readings, and no reading at all at idle. It's mesh is trashed.

So, were are waiting on parts.

Jaguar in their infinite wisdom, no longer make part number LNA1620AA the airflow meter. We are sourcing another generic, can't tell you what brand, but from SNG Barrats I think.

Genuine Jag Ox sensors are quoted as NZD$1500 each and I need two (!) so we are getting some other ones that are a reputed brand, can't remember exact brand but something like NTK.

I hope this will sort it out.

The alternative is to go back to std ECU, but tried getting one of those lately?
The car's vendor has the original but is keeping it for another XJR6-engined project. however I may be able to copy the software from it if necessary.

Has anyone had to buy a new non-OEM Air flow sensor?
Any advice?

The XJR one is specific to that model, and can't be replaced with the normally aspirated part..

 

the lack of replies to my post, apart from very helpful emails from Andy, is consistent with the trouble getting a new XJR air mass flow meter...

There are, simply, no new genuine Jag ones out there, although somewhere on a dusty shelf one will be hiding.

So I have bought a secondhand one from ebay which they say works (50 pounds), and a new non-OEM one from World car parts for 100 pounds (also UK ebay)

I will let you know in about two weeks how this works out.

 

If you know the measuring range and output signal of the MAF (or maybe Andy knows it?) then you could go for an aftermarket "tunable" MAF like from Promracing.com - The Standard of Mass Air Meters! or there are others out there too.

You can tune these to match the factory range/output.

Not cheap, but another option, if you know the details of the factory unit...

 

I have two new XJR air flow meters
One genuine Lucas, 50 quids off ebay,
the second non-genuine but brand new (100 pounds)
Note mess is finer on the Lucas, and the mesh on the new generic one if slightly buckled, so not as good quality, though it's the electrical performance that probably matters more..

Now all I need is my mechanic to come back form his week of holiday!

I will post how this works out, eventually.

The old saying "If you own an old Jag, you need two" has proven correct - I am still running around in my 3.2 Daimler.

 

I spoke too soon...
my Daimler's rear window broke when a stone flicked up today, so now that is off the road too..
As well as my dad's vintage Alvis, which broke a pushrod 2 weeks ago


that is all 3 of my Coventry cars out of action at the moment.

 

update -
after 2 weeks off the road, there is some light at the end of the tunnel.New oxygen sensors and airflow meter didnt change the poor idle when warm.
Mark the mechanic has found a leaking actuator in the induction system, and this needs replacement.
Also a pin is missing from another actuator (not sure of exact part), this probably slows closure of throttle when hoof removed from the righthand pedal, and this may also explain stalling when foot suddenly taken of the gas..

so still some work to do, but heading in the right direction.

 

I had a saga getting my X300 Sovereign to run right. Eventually the car was fixed by changing the ECU and the coils. During the process, many things were tried, including replacing the airflow meter. I bought a generic LHE1620AA air flow meter from worldcarparts.co.uk and as my car is running fine, I would guess the air flow meter is OK. As for ECUs, I could not find a new unit. I agonised about using a second hand unit, but a second hand unit from xjsstuff.co.uk did the job nicely. I also saw units on Ebay. Hope this helps.

 

So the can of worms is open..
long story short, new AFM and oxygen sensors made little difference, modified ECU still not talking properly to 1990s Jaguar PDU.
Mark has found a leaking actuator in the intake system, which when isolated improves idle substantially. New one on order.
Also, a pin is missing from some part of the intake control system, and this is on order.
The supercharger is very rattly, and this is hopefully only a coupler, but if it ends up needing removal I figure it is worth replacing the dreaded octopus hose at the same time.
I have found a new M90 supercharger in the States, and bought it - hoping not to need it yet. I have a coupler and nose-cone rebuild kit on the way for the blower.
If, at the end of all this, it is still not talking to the PDU, I may take it to Beacham Jaguar which is nearby. They have the latest diagnostic gear which will hopefully succeed with talking to the ECU..

updates to follow..

 

Do you have one of the better OBDII scan tools? Mine will display a data stream so I can see what values the ECU is seeing in real time. I can see the O2 voltage swinging from high to low for example (as it should).

 

As a thought, if you have poor idle, have you checked the output of the coolant temp sensor? Is the thermostat ok and is the car coming up to temperature?

As a "quick and dirty" test, unplug the lead going to the coolant temp sender when the car is hot and short the two terminals on the harness. I've used an unbent paperclip, but any short piece of wire will do. This tells the computer that the engine is fully hot and should pull out any warm up enrichment. If it runs better than your coolant temp sender is bad.

Does your exhaust smell as though the car is running rich? If you had a scan tool I believe the better ones will also report intake manifold pressure ( i.e. vacuum) and that could tell you if you have a vacuum leak. Of do it the old fashioned way with a gauge!

 

So I went to see my car today, a bit like visiting hospital.
The supercharger is off, the new octopus hose has arrived. The water pump seems OK but very crusted up where the hoses attach. the intercooler looks good and clean.

The old supercharger has a flogged out cracked coupling (one of the spring loaded ones). The short snout seems to have smooth bearings. the rear needle roller bearings have slight play when the rotors are grabbed through the rear air entry port and jiggled. I think it would be perfectly servicable with a new coupler, but I have a brand new one on it's way form Ebay USA, so I see no point in putting the new one on a shelf. It is going in the car, then I can decide what to do with the old one - it would make a great ornament...

We are getting a new waterpump while it is all apart and accessible, new hoses, and checking out the electric waterpump for the intercooler. Does anyone have any experience of the intercooler pump failing, or are they fairly reliable?

Progress....