Hi i have a fiat punto mylife 2011 its misfiring in cylinder 2 and 3 as ive scanned it with my friends obd scanner ive changed spark plugs and coil pack ive also checked the fuel injectors and none of them look worn out or burnt an i have no clue what it could be (87k miles)
Technical cylinder 2 and 3 misfire
- Thread starter igord123
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Technical cylinder 2 and 3 misfire
I assume no loss of coolant?
So maybe a compression test to rule out anything major.
Do the old plugs on 2 and 3 look different from the others?
Any air leak on the inlet manifold?
coolant did start leaking however ive flushed the coolant out and put new one in and fixed the leak. i had mechanic change all spark plugs and coil pack so im not sure what they looked like and i have not checked for an air leak .
If engine lost water and overheated a head gasket can leak between two cylinders, so keep an eye on the coolant level and engine temperature.
If engine is misfiring/loss of power etc. I would have expected the mechanic to check further re the fault in the ways I have described.
Also check if heater is working correctly as sometimes the first warning is the heater blows cold due to air in the pipes so water not circulating.
They can still do all of that , but even a small amount of water can cause a misfire.
However another test would be to run the car with diagnostics such as MES connected for live data as the engine misfires.
Sometimes a faulty wire can cause a misfire,
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Small leaks can not be detected with compression test.
But should be visible during leak-down test (different tool).
Or modern methods like oscilloscope + pressure transducer in the cooling system (spikes of compression will show up).
Sparkplugs visual inspection is a very basic thing to do (and to document, picture). Your mechanic might not be the best one. Look for different one next time.
But should be visible during leak-down test (different tool).
Or modern methods like oscilloscope + pressure transducer in the cooling system (spikes of compression will show up).
Sparkplugs visual inspection is a very basic thing to do (and to document, picture). Your mechanic might not be the best one. Look for different one next time.
I fully agree about "Small leaks can not be detected with compression test." my comment was in relation to the misfire owing to OP already trying plugs and coils etc. rather than the coolant issue, just to ensure there wasn't low comprssion issue causing the misfire fault.
Thank you for the advice re "leak-down test (different tool)
." I was using a Sun Tuning version of that in the 1970s when foreman of a Dealership and also have a Bosch version for my diesel work in the past, so have have used them many times and appreciated the benefits they offer and have also advised Forum members in the past of there uses when trying to locate certain issues.I freely admit little experience of using "modern methods like oscilloscope + pressure transducer in the cooling system (spikes of compression will show up)." as after starting my own small Motor business in 1982 there wasn't the demand to warrant the added expense with my regular customer base.
