P0300 after Thermostat change

Dex-focus · Jul 24, 2013

Hi I have a 2002 petrol 1.8 16v zetec that recently had the cam belt go taking out most the car with it, so had the usual done.. new valves/head skim/gaskets/Cam belt and injectors. The car seemed to drive fine for a while then one day I noticed all coolant was suddenly gone, so had the thermostat changed and now the CEL is on (reading P0300 Cylinder misfire no#4) and the car has lost power especially at 2000rpm in 4/5 gear and does no want to pull going up hill (CEL will flash but stops on comming down hill). Tried new plugs HTs and Coil pack but still apparantly misfire on cylinder four ? While going through all the work that had been done on the car before I owned it I have found an Emissions test that has a note on bottom saying..
Engine speed measurement - bypassed
Engine oil temp sensor - bypassed
Could this be part of the problem if the Garage have installed everything as it should be without them knowing about the possible bypass ? also since the thermostat was changed I have found a Black/Orange line wire with a connection on the end with a Yellow centre [dunno], it seems to run from across the left top side of the engine to the right hand side across the top and would only seem to reach as far as the thermostat or Fuses/Relay boxes or maybe behind minfold just the one wire on its own, I have had a look at the Relay box and it looks as if an entire row of relays is missing [screwy] any ideas would be much appreciated either on the wire or the possibles for the misfire reading TY

Hardline · Jul 27, 2013

P0300 is actually Random/Multiple Cylinder Misfire. Check your code again.

zetecDon · Jul 27, 2013

Moved to "General Technical Chat".

amc49 · Jul 27, 2013

Common for lots of relays and fuses to be missing, many cars do not use them as they are for options not on all cars.

The 'bypass' thing if like in the states just means the things bypassed do not affect emission testing where you are at, so inspector just checks them off as 'not needed' or bypassed. Here in states they are often marked as 'passed' automatically since they are not even checked, it being unnecessary to do so. The few states needing them will mark them as appropriate.

tmittelstaedt · Jul 27, 2013

all coolant suddenly gone? With no leaks anywhere? Now a cylinder misfire?

Do a compression check on that puppy. I'm betting a reassembly error on the engine and the head gasket has failed. Or someone took a shortcut and tried reusing the headbolts and one of them cracked. Or the timing belt jumped a tooth and the head gasket is fine. Have you checked for coolant in the oil?

Didn't whoever did the work give you any kind of warranty?

Dex-focus · Aug 1, 2013

Not seen any water in the oil yet and had compression test done which came back as cylinder #1-135, #2-140, #3-130 #4-130 which my local Ford dealer says is ok ?.
After about the 25th time on the ECU she is now coming up with intermitent misfire on Cyl 4 and intermitent injector on 2 . As for the garage I have been back to him multiple times and he has been happy to help ECU readings etc but would now seem to be at a dead end as to what the problem could be

ok so had a real good look in the Haynes manual and under the bonnet, and there seems to be no radio suppressor would this cause an issue such as this ? there seems as if there was deffo something behind the coil pack which the cable had gone to, I can tell the cable has only recently been left hanging as there is not enough dirt/oil on it for it to have been like that even in the five years that I have had the car ? thanks for the replies and info guys

This car is driving me off a cliff slowly [bash]

P0300 after Thermostat change

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