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Misifirng when hot

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Old 27 July 2012, 05:15 PM
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jabran200
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Default Misifirng when hot

I have this strange issue with my car and I can't get to the bottom of it.

It is fine when cold but after about 15-20 minutes idling it develops an intermittent misfire which becomes more frequent as it runs and can't really boost it or drive it at all as it splutters.

I installed some newage coils as the old ones looked a bit old and cracked, I have changed the plugs too. I also cleaned the crank and cam sensors and check resistance, crank is 2.8 kohms and ccam is 2.4 kohms.

Specs are:

sti v2
esl ecu/daughterboard mafless
newage coilpacks
td05 turbo 1.4 bar boost
fmic
sytec fuel pressure regulator
equal length manifold.
Old 27 July 2012, 05:27 PM
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Infected by sti
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What plugs are you running?
Certain plugs may cause this problem due to different temp ratings, also check the gaps on the plug are correct.

All the wiring nice and tidy where coils were changed? Nothing breaking down under load when hot is there i.e wires touching or earthing?
Old 28 July 2012, 01:10 AM
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Ginola
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lazy injector?

have a similar problem.... I think....
Old 28 July 2012, 07:27 PM
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jabran200
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change to a new set of copper plugs today with 0.7mm gap which felt better but once it got hot the misfire was there again.

All the coil wiring is fine, I have checked it all and it is all insulated.

It starts off as an intermittent idle misfire which comes and goes but you can drive it fine and just about notice here and there. Eventually it stutters in the low revs but as you get past 4000 rpm you can't feel the stutter and it drives through the rev range.

how can I check for lazy inejctors?

what are your symptoms Ginola?
Old 28 July 2012, 08:49 PM
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Ginola
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Occasionally runs on 3 cylinders for a moment when hot started, drives ok, lumpy through hard acceleration, couple of times ive had loss of power (very noticeable) over 6000rpm Feels like a cylinder stops working and sounded odd too, been told to drive off boost/not drive it till can test.
Old 28 July 2012, 09:20 PM
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jabran200
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sounds different to mine, my car misfires only after about 20-30 minutes. when it is cold it runs fine.
Old 29 July 2012, 10:41 AM
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jabran200
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I have noticed on the diagnostic machine the lambda shows 0v all the time and when it is disconnected it shows 0.3 volts. Could a faulty/disconnected lambda cause this issue?

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Old 06 July 2015, 09:40 AM
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telemarker
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I appreciate that this is similar to grave robbing ;-), but did you get to bottom of your misfire problem?
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