Bosch L-jetronic problems

[Michael D. Porter]

Tim Willis wrote:
> 
> Hi all,
> 
> I am in need of info on when and how the cold start injector works on the
> Bosch L-jetronic, as used in my Rover 3500 SD1.  I have just completed an
> engine rebuild and there is a fairly bad miss while the engine is cold, it
> is there through the rev range.  Does the cold start only work once while
> the starter is activated or does it continue to pulse until temperature
> rises to a certain point.

On the Japanese L-Jetronics, and I'd presume Bosch to be similar, the cold 
start injector only opens when the block temp sensor is below something like 65 
deg. F, and the starter is engaged.  And, further, there's a bimetallic switch 
in series between the starter switch power and the cold-start input line, so 
that if the engine doesn't fire after several seconds of cranking, that input 
line shuts off, to prevent flooding.  The only time the cold-start injector 
should give any problem after the engine's started is if it's leaking.  When I 
worked for Toyota, we saw intermittent missing after a couple of years of 
running which had nothing to do with the injection system--all related back to 
how fuel was injected--created some carbon deposits on the valves and seats.  
Clean the valves and it was okay.  On this, might want to check the temp sensor 
in the block and see what its resistance is (should be high--25-30K ohms, I 
think), and check the cold-start for proper flow and resistance to leakage when 
the fuel system is pressurized.  
 
> There is what appears to be some sort of air bypass, aluminium about 2
> inches by 4 inches, and two 1/2 inch ID hoses (can't remember shere they
> connect), what is it and how does it operate.

That would probably be the idle air-bypass.  Little stepper motor turns a 
sliding plate in the orifice to control bypass air, and therefore control idle 
speed.

-- 
My other Triumph doesn't run, either....