What Changed After the Initial Review

Three weeks ago we pulled a 2JZ-GTE out of a customer's Supra for a routine health check. The car had been running rich at idle, and the owner suspected the injectors were past their prime. We ran a full diagnostic sweep, logged fuel trims, and checked the turbocharger for shaft play. The initial review pointed to a tired wastegate actuator and a boost leak at the intercooler coupling on the hot side. Nothing catastrophic, but enough to explain the rough idle and the occasional boost spike at 4,500 rpm.

What changed after that first pass is worth documenting because it shows how a single symptom can lead you down the wrong path if you stop too early. We replaced the actuator, re-tensioned the coupling, and re-tested. The boost spike was gone, but the rich idle remained. That pushed us to look further upstream: the MAP sensor was reading about 12 kPa higher than ambient at idle, which pointed to a restricted vacuum line rather than a sensor fault. A new silicone hose and a proper T-fitting later, the trims settled back to within 3 percent.

The lesson here is not about the parts we swapped. It is about the order of operations. If we had stopped at the first fix, the car would have left the shop with a persistent rich condition and the owner would have been back within a month complaining about fuel economy. The follow-up review added roughly forty minutes of labour and one hose, and it turned a partial fix into a complete one.

For anyone doing this at home, the takeaway is simple: after you address the obvious fault, re-check the original symptom before calling it done. Log the data, compare it to your baseline, and only then decide whether the job is finished. That extra pass is what separates a repair from a diagnosis.