This "work around" method is quite common apparently. The problem is that sports cats have a higher gas flow velocity than standard units. Standard units are so full of cat media that gas flow is slow and heat build up within the cats is faster due to the restrictive nature of standard 600 cell media. The sports cats flow faster and heat gets away quicker as well. That is what caused this slight issue this morning.
Compare if you will, the MOT results from my car last year with standard cats fitted and then the results from this mornings session.
So for next years test, I am suitably knowledgable to be able take this slight problem as it comes. Although a cold cat issue exists, heating before test makes a test pass possible even with highish CO levels still being a feature of fitting sports cats. It is a bit irksome, but that would appear to be the price you have to pay if you want this type of performance upgrade.
The gas test as performed at the MOT station is rather curious. One would have thought that doing the test immediately a vehicle arrived on site would be the done thing. I suggested this to the ever helpful Halfords tester and he said that it could only be done at the end of the session. Presumably to weed out cars like mine that may be border line on gas output levels.
Dan at Longlife Exhausts had other points to make. That was the age of the test machine, accuracy and degree of accurate calibrating possible on elderly test gear. He had dis-guarded an old machine recently in favour of a brand new unit. Results were as like a chalk and cheese.....So perhaps avoid a test station that does not have an up to date gas test unit. Even test gear can eventually loose the plot!
So now with a nice new test certificate in my hand, I`m set for another year of mayhem.
Take another look at the results of my last MOT gas test which found high CO readings which I thought may possibly be down to sports cats loosing temperature in sub zero conditions when the test was conducted. It was sumised that the faster flowing cats were responsible for the high emissions results. Things may have now changed. I do hope that is the case and that I may now be able to get these emissions issues under rather more control.
Following the MOT test this year, I continued to use the car with no further investigation until recently. MPG figures have been quite acceptable but the car can be smelly on start-up and sometimes even when fully hot. I took third party advice from my old friend, Lawson Smith at Powerhouse Automotive. Lawson considered that 200 cell cats should easily be able to pass an MOT without any difficulty. He also told me that difficulties might have arisen if I had fitted 150 cell units which might have lead me towards fitting mini-cats units down stream of the cats. 150 cell cats are usually only fitted to off road racing type applications.
Essentially a mini-cat is a tubular unit which screws into the downstream lamda sensor exhaust spigot before the down stream sensor is then fitted into the other end of the mini-cat. That provision would help the ECU in as much as it would buffer the readings between upstream and downstream lamda sensors and prevent engine check light illumination and fault code generation. Mini-cat installations help shield and de-sensitise the ECU in modified and tuned cars. However, Lawson did note think that this was my real issue.
Use of the car since the MOT without mini-cats being fitted has continued to be a bit problematical on a worstening basis. PTJS1 gave me a hand itemising the problem which is not getting any better. I discount the methanol/water injection system use as the issues that are now becoming more frequent, occur even with the water/methanol being switched off. The problem occurs most significantly, if only occasionally, when after a hard blast of engine use then subsideing to a cruising condition. In some instances the engine check light will illuminate for no apparent reason. The car continues to drive perfectly normaly. MPG still remains very acceptable. Electronic diagnosis consistantly reveals a PO430 Bank 2 fault code which implies the near side catalytic converter is below threshold limits. In other words it has become inefficient due to some incident having taken place which causes the engine check light to illuminate. A PO430 typically implies a problem with the downstream/post cat Lamda sensor and its feed back relationship with the upstream sensor.
PTJS1 recently helped me set up screens on my Torque Pro Android phone to monitor Lamda sensor activity. Those screens have been most revealing. Bank 2 is the N/S four cylinder bank of this V8 engine. The PO430 issue is focused on that near side half of the engine and its control equipment. Normally the screens on the Torque Pro app would show both Bank 1 and Bank 2 Lamda O2 sensors showing similar oscilating traces at a general operating voltage of around 0.6V. The graph on the screen shows all fluctuations including normal activity. With a duff sensor, the voltage trace for that unit dramatically falls, then "flat lines" at the bottom of the graph at a voltage of just 0.1 or 0.2V. The damning evidence is there for all to see. This disruptive flat lining is unacceptable to correct engine running and implies that the near side down stream sensor is failing badly. Further advice taken from my favourite local Jag Tech at our Regional Meeting this evening confirmed that in his opinion, that near side post cat Lamda sensor was in trouble. Mileage covered is just under 89K miles and apparently is about the normal mileage when one can begin to expect these O2 sensors to begin to fail. So the Bank 1 sensors continues to function as it should, but the nearside Bank 2 unit is almost certainly at the end of its useful life. Its much better to find the possible cause, rather than not to be able to find a fault at all!
I`ve decided not to buy a cheap Chineese sensor. I don`t have the physique or patience to risk having to do a repair job twice. Gendon sell quality Lamda sensors so that is the direction I`m going presently. The precat sensors are £80 each with the post cat sensors selling for £40 each. There appears a VIN discrepency on the Gendan site as regards the VIN number applicability for their listed post cat sensor, so I`ve sent off a mail asking for suitability conformation for my car and am hoping for a reply tomorrow. MY, VIN, engine number and registration number inclusion form part of the information entered onto the Gendan mail system and is the basis for my request for precise part number clarification.
More on this matter soon as I attempt to fix this problem.
The pre-cat sensor is this one. https://www.gendan.co.uk/product_LBX0430.html
The post-cat sensor is this one. https://www.gendan.co.uk/product_LBX0429.html
Now ordered a post-cat sensor which will hopefully arrive with me by first class post tomorrow.
"Hi Mike Kennedy,
Your product has been gently taken from our shelves with soft cotton gloves and placed on a cushion for its journey to the packing area.
A team of 4 packers thoroughly inspected your item and polished it to ensure it is in the best possible condition before beginning the packing process.
Our packing specialist from Sweden lit a scented candle and demanded silence from everyone in the office. A perfect ambiance is required to allow him to achieve packaging perfection.
Once completed, we all had a wonderful celebration and the team marched to the delivery company, waving and spreading good cheer as we journeyed through Swansea. Everyone applauded, shouted Bon Voyage! and hugged one another as the van left.
Your parcel is being cared for by Royal Mail First Class Post. It should be with you in 1-2 working days.
I hope you had a wonderful time shopping at Gendan Limited. We sure did. Your picture is on our wall and we have nominated you for our Customer of the Year title. The whole team is pretty exhausted but can't wait for you to come back and shop with us again at www.gendan.co.uk
Thanks and best regards,
The Gendan Automotive Products team"
It isn`t often that one receives this type of customer care.....
Is there any chance that this followed a communication from you to Gendan saying that you were concerned whether they had the right part and could they guarantee next day delivery......
Reminds me of Rowan Atkinson gift-wrapping the necklace in "Love Actually"....."This is SO much more than a bag...."
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)
My enquiry was on the site email and the form just asked for reg number, VIN, MY, and whether pre or post cat sensors were needed. The reply mail didn`t seem specially written and my request for part number qualification was just matter of fact.
The jokular despatch mail was received after I placed my order on the site and despatch had taken place late this afternoon. I think they must have a joker in their despatch department!
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