MOT and emission test rules/etiquette

[Dick Cheeseburger]

I've used fairly friendly testers for my MOTs for the last few years, but today broke the mould. I took the MR2 to a garage locally which was offering MOTs for £25. That's unheard of around here. I know that there was potential for them finding lots of 'problems' as a result, but I thought I'd give it a go.

Anyway, outcome is positive. It passed - it's a thirteen year old car and this particular one is reasonably tired, so a pass was bloody fantastic.

However, I just wondered what the guidelines are on petrol emissions tests. The fella held it for a couple of minutes at high revs, at that was before he'd stuck his twiddler up the zorst. He then upped it to the point you could just about hear the bottom end rattling, for another minute at least.

I know it sounds worse when its stationary and you're not revving the shit out of it yourself. However, I was proper cringing and was ready for something to go bang.

I didn't think petrol emission tests now needed the shit wringing out of the motor for a prolonged period? Anyone know the rules?

[scaryoldcortina]

First job is always to run it up to about 3000rpm for a few seconds to purge the exhaust, then the probe goes in.

 

Next you need to hold the revs between 2500 and 3000 for the BET test (30 seconds) and if it passes this then you are basically done with no more revving, there is an idle check before you disconnect the probe. If it fails, cue up to 5 minutes of "cat conditioning" at up to 3000rpm, followed by another 30 second test.

 

It always sounds worse than it is, trust me.

[Jim Bell]

You can get around it all together by buying a brand new VW though.

[lisbon_road]

I think basically the plan is to hold the revs high, which prevents the test formally starting, and while the revs are high, the cat is getting as hot as possible to get a pass.  Then edge the revs down so the test starts with everything as hot as possible.

 

I say this from watching my tests where I know the examiner is determined to use anything he can to get a legitimate pass.  He says he hates failing them on emissions if he can get them to pass.  I always book the first test of the day and take the car for a good drive to get it all as hot as possible.  I help with the test (starting with making the tea).  

 

Part of this is that he knows very well that I fix 'em myself, so he won't get any money out of it.  But also partly I think as you can throw money at them with new cats and stuff and still not get an improvement.

 

I do think we are better off with an emission test though.  It is in all our interests that they should be running properly, and it is noticeable that if I maintain them well and especially if they run on a well set up lpg system, they just smoke it.  (or rather don't smoke it!)

[Dick Cheeseburger]

I took it for an Italian tune-up prior to the test, but I guess he wouldn't have known that. That makes sense that he's got the cat really hot prior to the test starting. I don't understand why he then took it to even higher rpm after he'd stuck the probe in, though. I'm pleased that the car went straight through - it proves once again that until very recently, J petrol cars really were the dogs gonads as far as reliability and longevity is concerned.

Despite the successes of today, I'm tempted to try elsewhere next time, as I'm still not convinced he that he needed to keep it singing at such high rpm for such a prolonged period. Having said all of that, the fit lass behind the counter and the £25 fee were still tempting. Don't tell Mrs TW.

[sierraman]

How many revs though? Was he bouncing it off the limiter at 6500rpm

[Richard]

What is the correct procedure for diesels? Everybody I've watched has just done a quick blip and got a fast pass.

[BorniteIdentity]

I think... in a weird way... he was trying to help ensure a pass.

 

Good news on another pass. Here's hoping the engine lives as long as the rest of it (!)

[omegod]

2000 rpm Is the fast idle test from what I recall when the local fella lets me play play at being MOT assistant 

[Dick Cheeseburger]

How many revs though? Was he bouncing it off the limiter at 6500rpm

 

 

Not on rev limiter, but not far off I wouldn't have thought. It sounded bloody horrendous.

 

2000 rpm Is the fast idle test from what I recall when the local fella lets me play play at being MOT assistant 

It was waaay above 2k for sure. I've vaguely known of the tester for years and he has all the mechanical sympathy of an ape. After he'd finished ringing the tits off it, both cooling fans kicked in - I genuinely can't remember the last time I heard both running. Feck knows how, but he managed to jam the engine hatch as well (mid engined) and I had to do lots of tapping the lid and pulling the handle before it eventually relented. Its never done that once in 13 months of ownership; I can only assume the idiot slammed it down with some sort of WWE move.