318i misfire @ 4500

[Hotjim]

Hi all. I have a 318i M40 cab and it feels like it misfires at 4500 revs every time no exceptions it wont kick back in till i go under 3500. Changed the plugs, leads, rotor arm, diss cap and had 3 guys from K2 Race Engineering look at it while it was in for MOT work. The upshot was they couldn't find the issue but they had all the diagnosis equipment hooked up and even while they ran it out the road but still no joy. Their hourly rate stopped any more work!
The next step i have been told is the injectors should i get them checked or just get a replacement and run through them?
Does anyone have access to reasonably priced injectors?

Cheers Robin

[maxfield]

You checked the camshaft?

[Hotjim]

No i've not inspected the camshaft yet. It's a bit tappy and i guess it needs replacing soon anyway.

[hongkongfuey]

have you chipped it,someone i knew chipped an m40 it missed at about that rev range

[maxfield]

Just whip the rocker cover off and look at the lobes.

It's only about 8 10mm bolts IIRC

[Hotjim]

Nope not chipped as far as i know. Where would the chip be and what should i look for?

[Hotjim]

ok maxfield i'll check it tomorrow. No garage and it's cold as hell tonight.

[Andyc02]

It sounds like the classic syptoms of a worn camshaft
very common on the m40 engine it wont rev/pull above 4500 rpm

[adam_b]

Mine has a similar problem, was going to change plugs leads etc. how common a problem is this on M40?

[mirage]

typical m40 camshaft worn symptom...mine is the same...thats why im swaping in an m20 into it...

[Jhonno]

sounds like a classic knackered M40 camshaft to me

[Hotjim]

Cheers for the confirmation guys looks like the best thing i can do after reading this place to death is drop in an M42.

Although Mirage i like the idea.

[adam_b]

Will the M42 16v head go straight on to the M40 block?

[Hotjim]

I have no idea you'll need someone technical to tell you the difference if any. I was talking about the whole shebang if i can find a good one with gearbox for 300-350ish.