Hi there... just had my dear 1998 Daimler through the MOT... when they took the reading from the exhaust, it turned out that the puffs from the left pipe where within limit.... but the right pipe failed miserably and had HC of 150.. max allowed is 100 (the other Readings, lambda etc., from that pipe was ok though)


What has failed and what is most likely needed to be done in order to correct it?... or.. is there a way to shoehorn the car through anyway???


/ E

 

Some more information...

Had a look behind the throttlevalve and i can see that oil is pooling on the "floor" in the airintake housing.. and well, burning oil is not doing wonders with the HC value.. or?.. And why one only rh exhaust pipe having bad values... wouldnt both pipes had bad readings?

Can it be two problems? Oil airintake AND a bad rh catalyst?


Im freaking out... was abbout to sell the car..

Any ideas?

 

The large center box gives the gases a chance to mix, but the high idle test wouldn't. I'd think the catalyst is the culprit, but did you get the car stonking hot before it went in? This helps when marginal gases are present. Either the honeycomb has dislodged or there's a blockage (19 y.o. cat).

The oil is from the engine breather pipe, no harm in giving it a cleanup. Maybe a partload/full load breather check and clean - you can find these simple jobs in the how to section or stickies.

Also a blast of CRC contact cleaner on the MAF sensor, this all aids good mpg and emissions.

Stick a can of BG44 in the tank, a good SH catalyst can be picked up from any good Jag breakers or eBay and park it at the MOT centre so it's 'ticking' hot and it should be golden.

 

There were some threads about the same problem on this forum, so you might want to spend some time locating them.

From memory, additional to what Sean already mentioned, you can check the knock sensors (should give a code, but not always), and the upstream sensors.

Both will mess mixtures if not function properly.

You should be able to know a lot more on your mixture flow if you connect your car to Torque software, and read data 'live'.
It can be downloaded on your phone, and only requires a (cheap) wifi (for Iphone) or Bluetooth (for Android) adapter.

 

Prior to MOT i made sure that the catalysts where hot as hell.... but the gas check was done last thing, so that didnt matter at all.. in order to improve the MOT personal helth... they have moved the gas check outdoors.. and is the very last thing they do right after the brake checkup.. The MOT guy realized that the readings was really, really poor, so he actually took the car for an spin in order to make the cat hotter.. but for nothing.. the readings was still terrible..


The first thing i did at home was to search for air/wacuum leaks. With the engine running, i sprayed almost a full can of starting gas on it in order to see if i could disturb its idle rpm... but it was rock steady..


Then i checked the breathers and they where ok. The small breater tube on LH cover snapped right off like a dry twig though... i suspect it was cracked allready.. two layers of shrink tube in order to fix that.. i also did the bullentine on the little orfice hole.. it was not blocked..


Spark plugs was then checked for exessive carbon build up etc. but had that nice light coffiebrown hue.. no worries there..


-Contact cleaner on the MAF sensor... where exacly, do i need to spray/clean it in order for it to have the desired effect?


I actually got an wifi IOBDII reader and have had it connected a few times.. still looking for the optimal program to use on my iphone..


Since all other than the HC readings was spot on and the IOBD didnt flag for any problems i am leaning toward an bad catalyst.. better than pulling both cylinderheads for a valve checkup... atleast its the "simplest" thing to do right now..


I do wonder.. regarding the catalysts.. are the left and right hand catalyst the same on an left hand or a right hand driver car??


My plan of action look like this as from today;
-replace the rh cat.
-replace air/oil filter and engine oil
-clean MAF sensor
-a can of injectorcleaner in the gas tank.


/E

 

All Cats are the same from LH or RH drive. The Maf sensor is located on the induction tube just after it comes out of the air filter box, the MAF wires connect to it and there's 2 Pozi screws holding it, once out you'll be able to see the glass bulb you need to spray-clean, it should help a little. The BG44 is the only engine cleaner Jaguar use and recommend.

 

And now the conclusion...

I got myself a new set of packings, and nuts etc for the replacement of the r/h catalyst..

A used catalyst with the same partnumber as the one i had installed (NNC6700GB -r/h, one oxy sensor, and flanged in both ends) was found at an local parts dealer... i actually made him pull out a few so i could pic one that was good.. ie. nice and clean cheramic core..

Least to say it took a while to get the old catalyst out without ruin any nuts,bolts or pins... the 4 pins on the upper flange are more or less bound to come out when you try to loose the nuts though.. its a matter of careful benchwork in order to clear them of the old nuts.. At the lower flange i needed to carefully grind away half the nuts and crack them before they let go of the pins... and well... the two bolts that sequre the catalyst to a bracket snapped right of... so.. a drilling exersise there..

So.. what abbout the catalytic converter... well, i expected one that was burned trough.. or totally clogged with pitch black soot... but... it was empty... as in nothing there.. a void.. hollow.. with no traces of the cheramics what so ever... to say i got surpriced is an understatement..

Anyway.. to install the "new" cat was really simple.. everything in the reverse order... plenty of anti seize on nuts and bolts..
This is what i saw when taking a peek inside the old cat.. empty.. its not the core you see.. its the bottom of the cat where i put my flashlight..



This is what a good cheramic core should look like.. nice and clean, not burned trough anywhere or full of soot..


Here you see the top of the r/h catalytic converter, the plastic tube between MAF sensor and inlet housing removed for axccess.. oxy sensor on its way out.. The nuts holding the cat to the exhaust manifold are, when they are new, pinched a bit in order to secure tighter to the pin and not become loose to easy.. Be aware, they tend to cut in to the threads when backed off..

 

I took my Jag to the MOT for a recheck of the emission values today, and it went trough with flying colours.


Check of the emission under load, resulted in an HC of abbout 20 from each pipe.. i could clearly see how the HC value was dropping as the catalysts got hotter and hotter..


Thanks everyone for help and ideas with this!