Golf MK4 1.4 16V Mis fire rough running

[Mursal]

Piston rings don't "free out" I'm afraid

If you are coasting down hills, it will be difficult to find fault codes that are reliable enough to use.

Take the car for a hard drive, clear the fault codes and use conventional driving habits, see what happens. Its the cheaper option

 

[Caesar]

Hi All

I changed the Temp sensor and problem still persists but the codes only come back after a few days of driving and the Mis Fire appears to be really random!

If I hold the Left Hand Side engine Mount the engine ticks over smoothly! When I release it there appears to be 1 Inch play when it rocks back and forth.

With the Ross Tech Diag using Block Measures 14, 15, and 16 the misfire is detected randomly sometimes not at all and then sometimes the misfire count races up but no engine light!

The strange thing is the engine runs smooth on a decline but jerks on an incline when at a standstill.

 

[Burnerman]

Most curious! If an engine has a misfire, it will always shake as it gets out of balance....by holding the engine mount (which often allow lots of movement, especially diesels) you are reducing the shaking and therefore disguising the misfire.
As for the misfire showing itself only when the car is either on an incline or slope has me truly baffled.
However, the misfire isn't total i.e a cylinder isn't completely off - but partial.
Do we have a compression test result yet?
John

 

[Mursal]

Might be worth giving the wiring harness a good "wiggle test", you just might have a bad connection. Pull and push on the looms to see if the misfire changes.

Then let us know how the compression test goes

 

[Dave54]

Maybe this is a long shot, but there isn't water or something in the petrol tank that's sometimes getting picked up mixed with fuel when the car is on an incline is there?
Check the wiring and connections as already said, my old Passat with the Monotronic injection used to play up sometimes, different setup I know but a good clean around the various plugs would put it right for a bit.

 

[Caesar]

Hi All

Apologies for the late reply as have been away for a while. I did not get a chance to get a garage to do a compression test but when i fired the car and ran it for a few miles the below fault codes appeared!

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16688 - Cylinder 4: Misfire Detected
P0304 - 35-10 - - - Intermittent
17526 - Oxygen (Lambda) Sensor Heating; B1 S2: Open Circuit
P1118 - 35-10 - - - Intermittent
17606 - Oxygen (Lambda) Sensor Heater Circuit: B1 S2: Electrical Malfunction
P1198 - 35-10 - - - Intermittent

Readiness: 1010 0001

Now it appears the fault is with the Lambda sensors and am guessing it is the one near the Cat?

Is this actual a problem that could cause the mis fire or just coincidence?

Also does anyone know how much a garage charges for a compression test? Many thanks.

 

[Belle427]

A misfire can log multiple codes which is why its difficult to diagnose, other faults can too.
I dont think the lambda is your problem but heater circuit codes are normally pretty accurate, you can test the heater element using a basic multimeter.
There should be 2 white wires to the sensor, with it disconnected you need to see less than 20 ohms across these wires (open circuit indicates its gone)
Regarding the compression test you could do it yourself, its quite easy.
If your capable of changing a set of plugs it will be no problem, compression testers are not very expensive

 

[jonnyfishing]

Sounds to me like a sticking valve on no.4 cylinder.