Engine Misfire Repair
Also called engine jerking
A misfire means one or more cylinders are not burning fuel properly, so the engine shakes, loses power and may flash the check engine light. The cause is always one of three things: spark, fuel or compression. We identify the affected cylinder from scan data, then test each of those in turn. That avoids the common pattern of replacing plugs, then coils, then injectors one after another when the real problem was low compression on that cylinder all along.
What the job includes
- Fault codes and misfire counters read to identify the affected cylinder
- Ignition tested: coil, plug and lead on the affected cylinder
- Fuel side tested: injector operation, flow and electrical circuit
- Compression and leakage tested on the affected cylinder
- Vacuum leaks checked, which often cause a lean misfire
- Repair carried out and misfire counters rechecked on a road test
Signs you need this
- Check engine light flashing while the engine shakes
- Rough idle with the car shaking at a standstill
- Jerking or stumbling under acceleration
- Loss of power and higher fuel consumption
- A smell of unburnt fuel from the exhaust
Not all of these have to be present, and one of them on its own can mean something else entirely. That is what the diagnosis is for.
How we do it
Identify the cylinder
Fault codes and live misfire counters show which cylinder is failing and whether the misfire is steady or intermittent.
Test the spark
The coil and plug on that cylinder are tested and swapped to another cylinder to see whether the misfire follows.
Test the fuel
The injector is checked electrically and for flow, since a blocked or leaking injector mimics an ignition fault exactly.
Test the compression
If spark and fuel are good, compression and leakage testing on that cylinder identify a mechanical cause.
Repair and verify
The confirmed fault is repaired, codes cleared, and a road test with live data confirms the misfire count stays at zero.
How we work
The same on every job, which is why we can write it down.
Diagnosis before quote
We find the fault first. A price given over the phone for a noise nobody has heard is a guess.
The price is agreed first
You approve the work and the cost before a spanner is picked up. Extra work means another call.
Parts you can check
We tell you whether a part is genuine, OEM, aftermarket or used, and what each one costs.
Old parts returned
Ask and we will hand back whatever we replaced. It is the simplest proof that the job was done.
Book engine misfire repair
Fill this in and a person will call you back to confirm the time and the price. Only your name and one way to reach you are required.
Before you book
Questions we get asked
If your question is not here, ask it. We would rather answer honestly now than have you find out after booking.