4 and a half cylinder Alpina

[sportwagon]

4 and a half cylinder C2 Alpina

I have just started the engine on my C2 Alpina after a lengthy restoration and cylinder number 5 is out and cylinder 6 is not on full song.
The engine has had a full top end rebuild inc crack testing, new cam etc.
Compressions are good as is spark.
My thoughts are injectors, has any one had a similar problem?
Can the injectors be removed with the Plenum in place? Mr Haynes says not.
Help please.

[Simon13]

Mr haynes is right!

it can only really be fuel or spark

have u checked it's getting spark from all 6 leads?

i'd do the same with the injectors and go from there

[Jon_Bmw]

When you say plenum, i'm guessing thats the same as inlet manifold. If so, you can change the injectors without removing the manifold. Its a bit fiddly, but definatly possible

[jimerilo]

Best way to check injectors is to place one end a long screwdriver on top of injector and your ear to the other with the car running, you should be able to hear the injector tick. If not theres your problem.

[k130]

Best way to check injectors is to place one end a long screwdriver on top of injector and your ear to the other with the car running, you should be able to hear the injector tick. If not theres your problem.

Unless it is blocked in which case it will still click as the solenoid will actuate without delivering fuel.

[buster]

yeah you can take the injectors out without removing the inlet manifold but i dont think thats the problem.
Id try putting some fresh petrol in if its been sat for a long time.You could always try some injector cleaner.
How do you know 5 and 6 are the problem ? have you tested all the leads for a spark ? also,you say its been rebuilt top end,are you sure the cam timing is correct and not maybe 1 tooth out ?