Testing times at the MOT station.

[Alan Faulkner-Stevens]

Despite being involved with motorcars I have always found a trip to the MOT station for my CRS's yearly check up a slighlty nervous occasion. Because despite all the best planning and checks a fresh pair of eyes over ones car can turn up a small problem. On this years test the mechanical scrutiny and road brake test all proved very satisfactory and all was well until the final emissions test on the engine. The CO and HC levels were passed very easily but the Lamda sensor readings were much to high. A reading of 1.03 is the required maximum but initial checks show the CRS at about 3.00. However you are allowed to raise the engine rpm up to 3000 and hold it at this level to allow the hot gases to pass over the Lamda sensor and clean it and hopefully see the levels drop. As the seconds/minutes passed with the motor running at 3000 the Lamda started to drop, with it easily reaching 1.10/1.12 at which point it refused to go any lower. The engine had now been at this level longer than I would have liked and to the cars favour all the instruments showed all was well however I was concerned that there had been no cooling air passing over the engine and exhaust components. My MOT man suggested a slight drop in rpm back to 2400 and this saw the final reading drop to the required 1.03. Then 30 seconds held at this rpm and the pass was complete. With that it was off the ramps and out into the yard to cool off and it wasn't a moment to soon. The car was not happy about the exhaust temperatures it had seen and refused to idle properly. So a quick shut off and allow her to cool. I get my MOT's at a local Morgan garage and it appears many of the low milage V8 powered cars, which are similar in circumstances to my own, suffer from the same problem. The mechanics now run them up and down the village at 3000rpm in first gear to get the Lamda sensors hot and clean prior to teating. This will normally rectify the situation. A good blast at higher rpm in a lower gear my do the same job I think. Finally once cool the engine started and ran sweetly, however then came the next problem which was a very hard clutch pedal. Upon inspection the bottom of the clutch cable is also quite close the exhaust maifold union and it has dried out the cable assembly. Despite working okay the pedal effort was increased and the feel was poor. I drove the car home and allowed her to cool off properly all was well but the clutch feel was still poor. To that end it was very easy to take out the drivers seat and release the end of the clutch cable from its mechanism.Once the cable boss had been unscrewed from the bulkhead and the cable released copious amounts of 3in1 oil could be poured down the cable. This has improved matters greatly. It appears then that if you are stopped on the way to the MOT station running your Cobra at a slightly more enthusiastic pace than you should be you can genuinely tell the Bobby you had to do it for the cars MOT!!!!

[C9OBY]

Thanks for the advice Alan. Mine's up for it's next MOT in 3 months time.  Key question for me this time round is whether or not to put the CAT's back on for the test (taken off last year after it passed it's MOT)....!

[Alan Faulkner-Stevens]

It may be advisable, if you can, to get access to an exhaust gas analizer and with the engine running you can check its emission levels. My suspicion is that without the cats you may not fall within the required tight tolerances. If you can check prior to the MOT test itself the result may well make the decision for you about refitting, or not, the cats.
   Alan Faulkner-Stevens

[Mark-Anthony]

Well C9OBY if you do manage to get through the MOT without the dreaded cats let us know.  A few extra horses for no cost?  Sounds like my sort of game.
   
   (Having just spent several hundred quid buying high-flow high performance replacement cats for the Beast - I'll be sick as a pig if you get away with it!  Pleased as punch too!)
   
   If you can follow AF-S's advice and put it on a gas analyser to check it first then do that.  One word of advice if you know an MOT station where they'll turn a blind eye to the odd incorrect gas reading - DON'T DO IT.  You'll invalidate your MOT (criminal offence) which means that your insurance will be invalid (another criminal offence). For "invalid" read "personally liable" and be prepared, if you've damaged anyone or anything, to be sued into bankruptcy.  I jest not.
   
   Frankly though I think you're both barking up the wrong tree.  You should do what I've done/am doing and modify (and keep modifying) your cars so that they're never actually on the road!  Thereby bypassing all this MOT rubbish!
   
   M-A

[MkIV Lux]

MOT passed today!!! Wow!! They even did not test emissions!!! This is Luxembourg! Next time someone will find that the bumper sits 3 mm too high ;-)
   
   My local garage (who owned the Mk IV before) advised to plug out the narrow air connector  that fits to a round shaped plastic box, about 5 cms in diameter on the passenger foot well (on left hand drive car), before going to the MOT. Don't know exactly what it does, but I've never had problems with emissions at the MOT.
   Try it out
   
   Regards
   Constant