The Gelopy (Diagnosis #2) returned to me for a little more TLC
While i was driving the vehicle up and down to allow its brake pads to start to settle, it became very clear the engine wasn’t giving all it could give
So what did i notice
– The idle was steady – but not smooth all the time- While taking off the engine was hesitating and missing within high engine load and low engine RPM
– The misfire cleared once the vehicle started to move, not so noticeable once moving
When i questioned the customer about this weird behavior, it turned out they had noticed the same thing, that it just wasn’t happy, and had been doing it for a while
Mostly when you were powering out of corners, and just daily driving
So Diagnosis time
So what am i suspecting to be at fault
Since the vehicle is a direct coil ignition system, it rules out HT leads
So leaving 1 of 4 options
-Coil pack failure
-Spark plug degraded
-Injection fault
-Compression related misfire
Decided to see if the cars on-board computer had noted any faults (looking for misfire codes) to start with
Using a Maxiscan MS309 – Using the CAN OBDII communication method
Which revelead no fault codes detected, the vehicle wasn’t aware of the misfire
Since Spark plugs are service items, and most likely cause next to coil packs, the spark plug gaps and tips were checked
Autodata list the vehicle as using a gap set of 1.3mm on all spark plugs
Armed with this, disconnection of the coil wiring and coils allowed the spark plugs to be removed for inspection
First impression lead me to a strong possible cause of the misfire
Overheated – white tipped deposits (lean burn) with owner stating plausible 60k has been put on them
FomoCo plugs don’t seem to show up on Google unlike rivals like NGK / Champion / Bosch etc
So i suspect these are possibly cheap plugs too.
While the coil packs were free it was worth checking the low and high tension reading to ensure a dying coil pack wasn’t a contributing factor too
Auto-data states that
Low tension side (pin 1 and 2) should show 0.7ohms
High tension side (pin 1 + HT) should be 5000 ohms (5K Ohms)
Each component was tested and all provided readings close to the specification above
Each coil pack showed higher resistance on the high tension side, but still remained close to the 5kohm limit
Further providing evidence that the spark plugs were to blame
Sourcing the Parts
Local Auto shops wanted Silly money for the vehicle – £10 per plug = £40
However an Online Supplier came to the rescue for under £25 delivered for a Set of NGK Premium Iridium tipped plugs (ITR6F-13) for the vehicle
The Final Stages
Once the plugs had arrived, they were gap checked, as you never know
Fitted and nipped down to ensure a tight seal
The coil packs were reseated and connected – ready for a Instant test
Engine started without any problems like before
with a happily idling engine better and was happy smooth revving engine, the misfire was cured
Again as i like to – i want to ensure that the repair has been successful
I checked with the owners again to even though the ‘gelopy’ had only done a few short runs
And to quote the customer stating
‘Awesome – can go fast again’
To Round Up
NGK state this sort of deposit is related to Oil contamination/leakage, poor fuel quality or engine operation periods
Since i know this vehicle is often left only a short period before been taking off again, i suspect the age of the engine and heavy use was the cause of the plugs failings
bbautorepairs 