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Discussion Starter · #1 ·
anybody have the same misfire/racing at about 1300/1800 revs if you try to hold revs it just goes up and down about 2/300 revs checked most leads to inj stuff i have new lamda new airflow meters as i think most replies will say check these all help will be greatly appreciated eek!
 
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Discussion Starter · #2 ·
I too have this problem and as I remember so some others.

The common theory is that this is where the variable valve timing kicks in. The symptoms seem to range from a flat spot with not much variation in revs to a case like yours which includes a misfire- BTW does yours also miss at around 2K and 3K?

Having had a poke around, the misfire ceases if I disconnect the throttle bypass valve- therefore I am leaning towards the idea that the mixture is over-lean- possibly due to an air leak or maybe dirty injectors. It certainly doesn't look as though it's ignition based. I need to try disconnecting the lambda probe next to force the injection into open loop mode- this would richen the mixture slightly as the ECU substitutes a "get home value" for the lambda reading.

The oscillation may or may not be significant, I personally am more worried about the misfire.

The car is booked into Mangoletsi soon, I'll post the results.

Simon
 
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Discussion Starter · #3 ·
thanks for the reply i noticed that there was a couple of people on the alfaowner forum saying they had the same prob and that one a145 owner had his throttle body replaced after a few other items and so far so good but this was under warranty interested to see the outcome though of your trip to mangoletsi
i bought an exhaust from them a while ago it was cheap until it rusted through the back box and when i went to get it replaced 10 months old they said yes its under gaurantee unless its dented,did not know until after 12 months that the dent in the backbox was meant to be there cant help but feel they were trying to mislead me and it worked havent been back since
 
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Discussion Starter · #4 ·
OH AND BY THE WAY MY CAR'S MISFIRE ONLY SEEMS TO HAPPEN AROUND THE 1500 RANGE, COULD BE WRONG BUT I WAS UNDER THE IMPRESSION THAT THE VARIABLE VALVE TIMING DOES NOT KICK IN TILL ABOUT 3000 REVS (THINK IVE SEEN IT ON A SITE SOMEWHERE) ALSO WHEN I ASKED AN ALFA MECHANIC HE SEEMED TO THINK THIS WAS NORMAL BUT CROSSED WIRES MAY BE TO BLAME AS I THINK HE WAS UNDER THE IMPRESSION THAT THIS ONLY HAPPENS WHEN NOT UNDER LOAD ,ENGINES WAY OF TRYING TO SAVE FEUL HE SAID BUT IF YOURS IS LIKE MINE THEN YOU CAN NOTICE THIS WHILST DRIVING SPECIALLY WHEN DROPPING DOWN TO SECOND GEAR TO HIT A CORNER AT SPEED IT SEEMS TO FAF ABOUT A BIT BEFORE IT PULLS AWAY SMOOTH
 

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I reckon your best bet is to get that car onto a diagnostics machine for a proper tune. Could be something really simple like a minor electrical problem or the car is badly out of tune. I had a similar problem that the car would not pick up after changing down and flooring it. It would hesitate before going. Turned out to be a bad connection from a lead to a plug. This is not always as obvious as a 'normal' 4 plug car as the engine still seems to run ok most of the time.

Well, if you cant afford the tune, at least shove all of your leads into place on the coils and the plugs, just to make sure :)
 

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Looking at a graph from my old car, I too got that blip. The graph shows one with a newly fitted variator, so that is what it is meant to look like. It also had a K&N and a Superchip, hence the smooth curves.


And before you all comment, yes it was pulling 132 bhp at the flywheel. Since then I got the exhaust sorted and it felt like it's old 180 bhp!!
 
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Discussion Starter · #8 ·
thanks guys tried all connectors to leads one was damaged a while ago but replaced it i thought this was going to cure prob (henry do you mean this fluctuation is normal or is there aproblem i know my variator is a bit noisey) :cool:
 

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I think it might be normal. The variator is meant to kick in at 1500 revs under a 30% load (whatever that means!!!) If your variator is knackered, it rattles and loses some low down torque, but no top end.
 
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Discussion Starter · #10 ·
cheers henry i did speak to an alfa mechanic and he said it was normal but did not think it should affect driving as it was just engines way of saving juice ,a 145 0wner had this pro but had the throttle body replaced and the prob went so going to take throttle body off and clean properly and also have injecters cleaned let you know how i get on
 
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