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Posted By : Jason Matthews, 26-Oct-2006,
04:53pm
Hi can anyone help with my 2.5PI problem? I've a Stag with a 2.5 PI engine from a 2.5 saloon (engine number stsrts MM so i'm led to believe its from a car
registered between 75 and 77). Problem is that when you let the car idle or lift off the throttle it starts to miss on one cylinder. It will then continue
to run on 5 for about 50 yards or so after you have increased the throttle. It's driving me mad! Also i can't find accurate timing settings for this
engine. I've one source that suggests 8 BTDC and another which suggests 2 BTDC. Any ideas would be gratefully received!
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Posted By : Jonathan Binnington,
26-Oct-2006, 05:36pm
jason, I have this with my 2.5PI spitfire, it idles on 4 or 5= cylinders but when the throttles are opened it chimes in with 6 cylinders. I think it is
due to poor synchronisation of the throttle butterflies, even though I have tried to even them out, once the buttterflies are a little open it goes
away quite happily on all six
oh by the way, try a new condensor in the dizzy
j
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Posted By : Vin Poonwassie, 26-Oct-2006,
05:46pm
people pay good money to make their cars sound like a Harley, you've got it for free!
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Posted By : Jason Matthews, 26-Oct-2006,
07:44pm
thanks. will give it a go.
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Posted By : Jason Matthews,
12-Dec-2006, 06:50pm
hi
turns out the problem is with the fact that the (gravity fed) fuel filter has been placed level with the tank and not beneath it. This means
that below 1/2 tank the pump is having to work much harder and so is not delivering fuel correctly. Also am told some of the injectors may need
a look at. I'll let you know when it's (eventually) running correctly!
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Posted By : John Davies, 26-Oct-2006,
05:44pm
Jason,
First, work out which cylinder is misfiring, by pulling spark plug leads.
Then check the feed line. You should feel them all pulse as the engine runs.
If that cylinder's fuel feed line doesn't, suspect a faulty metering unit
Then inspect the injector.
Take it out and look at the spray pattern - put it in a jamjar!
***Be careful with the fuel spray - stand down wind of the engine!***
It should be an even cone.
If it's not, try pulling on the pin at the nose with your fingernails whule the engine runs (risk of getting wet with fuel - CARE!)
This may dislodge a piece of grit.
If the injector will not revive - change it.
Several places offer exchange reconditioned injectors.
Then check the throttle butterfly is not loose.
After that, er.......
Timing - my Haynes says 8BTDC up to '72, and 10BTDC after that, but that was with 5star!
John
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Posted By : Vin Poonwassie, 26-Oct-2006,
05:53pm
IF you wanted to get away from the lumpy idle, as John said, pull the ignition lead on each spark plug in turn with the engine running and the one
that makes no difference is the cylinder not firing. Still with the engine running, if you then hold the nylon feed tubes to the injectors one at a
time and feel for a pulse, if one hasn't got a pulse (or a weak one) then that injector may be fubar. Some say could be air in the fuel line to
that injector, but I've found that to be a myth.....
to double check, swap the suspect injector over with another and see if the fault follows it.
my bet is on an injector as they have springs that open to let fuel out under pressure when it's their turn to get it, could be something else but
I feel the 'force' is with me on this one - let us know what it is/was in the end....
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Posted By : Vin Poonwassie,
26-Oct-2006, 05:57pm
Ok, just read John's post again - looks like I just repeated him.......er......PI diags are PI diags.....