Re: annoying misfire

["jtrealtywebspannet" <jtrealty@xxxx>]

If the engine is not running smoothly there are 2 major reasons for 
it. There could be a breakdown of the secondary ignition system ie, a 
bad spark plug (worn, badly gapped, leaking, cracked) or a bad 
ignition wire. If it is breaking down in the well you can't see it. If 
the wires are old or look crummy or are hard just replace them. 
The other main area IS the fuel injectors. To do them properly you 
must remove ALL of them and put them on a Fuel Injector Tester. With 
this piece of equipment you can clean them, inspect the spray pattern 
and verify opening and holding pressure. I suggest you also replace 
the injector seals and the copper sealing gaskets.
Of course all of this is assuming the engine is mechanically healthy 
meaning you did a compression check and all of the cylinders are 
within 10% (5% is even better) and that there are no vacuum leaks. A 
local Volvo dealer should be able to check your fuel injectors or you 
can send them to a Delorean vender. This is something you cannot do at 
home without the injector tester. What you can do at home is to remove 
all of the injectors from the engine, place them in cups, disable the 
ignition system and crank the engine for about 10 seconds. Compare the 
amount of fuel in each cup. If it is different disconnect the 
injectors from the hoses and try again. If it is still different the 
fuel distributer may be the problem. One of the ports going to a fuel 
injector could be damaged or plugged up. Check the numbers on the 
side of the fuel injectors, it is critical that they are all matched.
David Teitelbaum
vin 10757


--- In dmcnews@xxxx, "jamesrguk" <James_rg@xxxx> wrote:
> Hi all,
> 
> I am still having an annoying misfire, I am pretty sure it down to 
an 
> injector that is passed it's sell by date, as it is not spraying 
very 
> nicely. 
> 
> To my knowledge the spray pattern on a mechanical injection system 
is 
> more crucial than on an EFI system because the valves are not always 
> open at the point of injection.
> 
> I am fairly sure the misfire is fuel related for the following 
> reasons:
> 
> 1) My timing light suggests that all plugs are sparking
> 2) All plugs are less then 8 months old. 
> 3) 2 of the injectors are new, 4 are 2nd user but appeared to be 
> clean and ok when 1st installed approx. 10 months ago, and the 
engine 
> has run fine until recently.
> 4) All of my HT leads are new as well as the cap and rotor arm.
> 
> Anyway my question is really why are the injectors getting blocked?, 
> have I just been unlucky?
> I have a new fuel pump, clean tank, and a filter on the fuel pickup 
> and had the main fuel filter change about 10 months ago.
> 
> Any ideas?
> 
> 
> James RG