I have a '98 Tacoma with the 2.7 l engine. It idles fine and runs ok at high speed , but right off idle it hesitates badly. Any ideas what to look at to solve this problem? There are no obvious vacuum leaks in hoses. I need help badly as driveability is getting bad.
Presuming it's fuel injected, an aging oxygen sensor that is beginning to get lazy can cause this symptom. The sensor no longer switches rapidly enough at idle causing a non-optimal idle mixture which manifests itself in a hesitation when coming off idle. If you have a scan tool you can watch the oxygen sensor behavior to determine if that is the problem. Good luck. Al
Wouldn't that trigger the check engine light? Most everything does on that system.
Clean the throttle body!
maybe a throttle sensor. about $50 DIY.
It might or might not set a code depending on how sluggish the oxygen sensor is and what the ECM logic is that triggers a code. If there are two oxygen sensors in your set-up, one in front of the catalytic converter and one behind the converter, the ECM will compare the switching rates between the two. A sufficiently sluggish front sensor can trigger a code (a catalyic converter code by the way and not an oxygen sensor code) if the two switching rates are far enough apart. If there's only one oxygen sensor, an oxygen sensor code will be triggered if the switching rate falls below a threshold. It all depends on how sluggish the sensor is and what the ECM logic is. A factory service manual should provide that information and a scan tool can monitor the sensor switching activity. Both are extremely useful, sometimes essential, to diagnosing such problems. Good luck. Al
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