Hi,

I need a little advice on finding a suspected air leak. I have been finding my xkr 4.0 ltr idle was a little lumpy when put in neutral and sometimes when you pull away from standing start it felt very slow.

There is also a faint tick when accelerating.

So I plugged it into my laptop and looked for any error codes and I found none.

I then started the engine and monitor its vital stats for a min. revving it to 2500 rpm for a few seconds and I noticed that the fuel trims were way off at idle speed but then settled around 0 when revved.

Has anyone else experienced these symptoms?

Am I right in looking for a air leak around the intake and supercharger and what would be the best method for finding it?

Pete

 

Sounds like an air leak. Can't say where so go hunting...

 

Start with the air intake tube between the filter housing and throttle body. The bellows often crack and the balance protrusions can melt near the exhaust.

 

Thank you this fault has been bugging me for a while I will break out the duck tape and start by sealing the joints and a very close inspection of the intake :-).

 

Another trick is to monitor the fuel trims and spray MAF cleaner on suspect areas. If there is a leak, the trims will go way down when you hit on the right spot.

 

This is good advice, also, if you have done any work to the engine, make sure vacuum lines around the throttle body are all connected.

 

Well I stripped the intake off and could not see any obvious wholes in it or melting. The only thing I could find was where the breather pipe joined the intake it was a bit wet so I degreased it and sealed it with hot melt glue for a temp fix.

I taped the rest of the connections and dip stick needs a new o ring.

I did a cold test and found the LT trims are now sat at 0 but the ST was still rich but I guess this is normal when the engine is cold I need to check when it is fully warm.


I will keep you updated.
Pete

 

If your dipstick needs a new O ring seal I would suspect that. Its an old buyers trick, hmmmm wont say any more on that front. We dont want to encourage dishonesty do we.

Can you seal it with something to see if it makes any difference?

 

well its just worn and dose not seal as well as it should to be honest as it looks original I wrapped it with duck tape for now a trip to the hardware store and 50p should fix it.

I will get it warm and remove the taped areas one by one till I find the offending seal.

:-).

I am not sure what you mean by an old buyers trick? can you elaborate?

Pete

 

You have a PM. As I said before dont want to encourage naughty behavior.

 

Even a tiny leak will be a problem and duct (duck) tape really isn't the way to go.

 

It is not being used as a permeant solution just looking for the leak which is tiny.

I am now leaning towards it being a faulty maf as the readings go crazy even when the car is not running under further investigation.

I might have to put it in to a dealer for a full diagnostic with the jlr ssd software.

 

I cleaned then changed my MAF. Made a big difference and its dead easy to change. Have you tried MAF cleaner? NOT carb cleaner.

For a bit of a guide you can take a look at what I did. Simply CLICK HERE

This is some before/after photos of the MAF on cleaning. Did look very different. click to see photos

Hope this helps.

 

You might want to take a hard look at the wires and the plug. Use contact cleaner to make sure you have a good connection. Sometimes, you can also do the opposite, and disconnect the air flow meter. The ECU detects it and comes up with estimated flow.

Also, you can clean the sensor. Use a dedicated spray (I use CRC air flow meter cleaner), not some random spray from the garage. Check the o-ring at the base of the sensor.

Last, consider just getting another sensor. In general, I hate throwing parts at a problem, but they are downright cheap these days (much less than any diagnostics fee).

 

Yep, you can get a MAF sensor on Amazon, sold by Walker, for around $35. and if you have prime you get it shipped free.

I cleaned the heck out of my old sensor with the CRC MAF sensor cleaner and it did not solve the problem. Sooooooooooooo................you might need a new one.

 

Yes I agree when these things go pear shaped its time to replace. I will get one on order asap and see if it makes a difference. If nothing eles its another thing ticked off the list I think I will also order a new fuel filter also as it looks like the garage also failed to change that like a requested :-(.


:-)

 

Well after trying all the things I could think of to find a leak I have to conclude I don't have one.

I bit the bullet and had a second opinion after not finding any sensors or leaks causing the fueling issue.

They advised me that I have a one or more failing injectors which is causing the car to be contently trying to correct the fuel trims.

Dose this sound right? and where is the best place to send mine for testing/rebuild if possible.

Pete

 

I'd run some BG-44k through it first, or a good fuel injector cleaner. It won't hurt and it might help.

 

"So I plugged it into my laptop and looked for any error codes and I found none. " Can you explain what system you are using to read diagnostics with? Thanks!

 

I didn't lock onto the faint tick you reported in your first post until a few minutes ago. It may indicate a leak in the egr tube that runs from the right side exhaust manifold to the intake manifold. It's a thin wall steel bellows known to form cracks.

If you can find a replacement it's very expensive and others have reported being able to weld it, but that sounds very difficult.