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RE: Fuel injector help needed

To: <shop-talk@autox.team.net>
Subject: RE: Fuel injector help needed
From: "Conrad" <conrad@conrad.uk.net>
Date: Thu, 3 Oct 2002 18:41:00 +0100
This has sat here unanswered for a few hours so I'll have a go. I'm no
expert but I do know a bit about FI.

> Cyl. #2 injector is not clicking.  (I have a stethoscope.)  I 
> swapped #2 and 
> #3 injectors and #2 is still not clicking.  It is apparently not the 
> injector.  I cleaned the connector on the injector but no 
> joy.  What is my 
> next step?  Does this mean my ECU is shot?  He77, the car 

First thing, check for obvious damage to the plug and wires for that
injector. Its possble that the female receptacle (pin) in the plug has
got pushed back into the plug so there is no (or intermittent contact)
with the male pin in the injector. Also, just to annoy the goblin (see
below) I'd pull the injector and check it actually definitely is not
squirting any petrol (aim it at a thick squished up cloth just in case
it is working). Viability of this depends on how your fuel rail is setup
tho - if the injectors are not clamped to the rail then they might just
get fired across the shop by the 50 odd psi fuel.

Is it sequential or simulateous (batch) injection (ie do they all fire
at once, or in sequence)?

If it is batch fire then its probably a dodgy lead to the one injector.
I'd probably bodge a 'T' from one of the other injectors and see if that
cures it (they are probably just all wired in parallel). You will need
to find out if thy are series of parallel wired before doing this tho,
schematic in the service manual will tell you. For batch firing it cant
really be the ecu unless each injector has its own drive, which I've not
seen. Might be different for you guys in the US tho.

If its sequential then is could be the ecu, although it could also be
wiring. If you take the plug off the injector one side should be
connected to 12v with the engine running. The ECU switches the ground
side. If you don't get 12v on one of the pins that's your prob. You can
compare it with a working one of course, as long as the engine will limp
along 2 cyls down. To fix this you could steal 12v from one of the other
injectors as the 12v supply is common to them all whether sequential or
batch.

If you do get 12v (in reality it will be more like 14v with the engine
running) then its either the cable from the injector to the ecu, or the
ecu itself. You should be able to pull the big plug on the ECU and find
the pin for the injector in question. Then check with a meter that there
is a good connection between that pin and the pin on the injector plug.
If that's good then its something ecu related probably. 

At this point if it was me I'd swap that pin/cable on the ecu plug with
that from another injector, and swap the same two injector plugs at the
engine end, and see if the dead injector moves over also, just to rule
out the silly laughing goblin thing that sits on my shoulder and makes
me come to silly conclusions. But that's just me. You might find
borrowing a similar ecu and trying that more effective.

Hope this is some help,

Conrad

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