'57 BMW 320i is driving me mad - injector, coil and MOT fail

[SpookiePookie]

Hello,

Firstly, sorry to bowl in without a proper introduction! I've owned my 3 series for about 20 months and have enjoyed it very much - until the past three weeks. A couple of weeks back injector 2 failed and then had a secondary fail on injector 4, so they all got replaced to the tune of £1100. Ouch, but I accept that bad luck happens and it was my own stupid fault for not being thorough enough in my research - I would never have got this car if I'd known that this engine is notorious for eating injectors and coils.

So, a week later and I feel like I'm running a little rough. Get it checked out and find that a coil has gone. BMW deny any fault, although I've read elsewhere that it's not uncommon for the faulty injector to leak petrol and ruin the coil & plug. Surely they should have noticed that the it was wet?

And finally today I got into Kwik Fit for an MOT and failed on a high lambda reading - 1.93 when the range is 0.97-1.03. The chap said that normally happens because of an exhaust leak, but mine is fine. I'm inclined to believe him because he'd be pretty motivated to sell me a new one. No warning lights either and surely BMW would've picked up a fault when they scanned the car last week. His theory was that they new injectors were not correctly coded, but he obviously can't know for sure.

My question is, is it possible that there is a relationship between the new injectors and the high reading? Or could I really be unlucky enough for the sensor to fail over the last week?

[RockyBalboa]

You really need to get some BMW diagnostic equipment on it as this will give a better idea of what/where the problem may be.

[mighty kitten]

There are a couple of BMW engines that run super Lean with a lambda of nearly 2.0 . They will be on the mot service emmisions book , come across this myself as an exhaust leak rarely sends lambda much above the upper limit unless it's a very large one . Pretty sure the direct injection is one of them

[SpookiePookie]

In a rare outbreak of common sense, I decided to look at last year's MOT reading and was quite surprised to see that the reading was 1.9 and actually passed. It says on last year's paperwork that the range was 0.7-4.0.

So, that probably means none of the injector nonsense is relevant. I'm still bloody confused though. I can only assume that one of the test centres has made a mistake.

Last year's has my car as 1971cc and this year's, the failed MOT, has it at 2171. What on earth is going on?

[Elliot2000]

They need to put in on the emission tester that it is an n43 engine and not an n45 which is the one that people normally choose, the other posters are right - it's a lean burn engine and designed to run to them figures - mot testers mistake

[SpookiePookie]

Thanks mate. So you're saying that 1.9 is normal and you think the guys who failed it were testing against the wrong engine?

[mighty kitten]

Unless your tester is a cyborg he won't have automatically known it was a Lean burn engine as they aren't common and I only see a few a year .shouldnt be hard to rectify with a quick check on the engine code for your car

[SpookiePookie]

Update: the car has been passed after I pointed the mistake out to them. It wasn't straight forward as there was a lot of "well, that's what it's coming up with when we type in your plate" and I was a bit frustrated that they couldn't just use some common sense. They also told me that my V5 must say it's the 2.2 version, but it clearly isn't!