Drivability & Misfire Diagnostics

Hesitation, a rough idle, a stumble under load, worse fuel economy than last year. These drivability complaints get dismissed as normal for the mileage, and they usually are not.

The difficulty is that the same symptom can come from ignition, fuel, airflow, exhaust restriction, mechanical condition, boost control, transmission behavior or engine management. Replacing the part most commonly associated with a symptom works often enough to be tempting and fails often enough to be expensive.

Drivability diagnostics narrow it down by testing. Live data and fuel trims, sensor inputs, compression, ignition activity, airflow measurement, fuel delivery and boost, chosen based on what your car is actually doing. Bosch certified diagnostic equipment and technicians who know how to interpret what it shows.

Subarus, Fords, VWs and everything else, especially the intermittent ones that other shops have already thrown parts at. You get drivability findings and priorities, in language that makes sense. If a shop has already replaced parts without solving it, bring us what they did and we will start from there rather than repeating it.

Intermittent drivability problems are the hardest kind, because the car usually behaves perfectly by the time it reaches us.

That makes your description genuinely valuable. Does it happen cold or warm? Under acceleration or at steady cruise? After the car has been sitting, or only once it has been driven for twenty minutes? In the rain? With a full tank or a low one? Every one of those details eliminates possibilities and saves diagnostic time you would otherwise be paying for.

Where possible we monitor drivability data over a longer road test or capture the fault as it occurs, rather than testing a car that is currently doing nothing wrong.

The other thing worth knowing is that a component can look bad because something else is wrong. Fouled plugs, a lazy sensor, a rich condition, these are often consequences. Fixing the consequence without the cause buys a few weeks and then you are back where you started.