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Matt
Matt, Mechanical Engineer
Category: Toyota
Satisfied Customers: 20593
Experience:  BEng, Repaired my own cars and others for 20 years, worked in Formula 1 for 10 years
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97 tacoma no codes warm no idle rough runing somethimes not

Customer Question

97 tacoma no codes warm no idle rough runing somethimes not all the time but when it does idle no trottle off idle
Submitted: 1 year ago.
Category: Toyota
Expert:  Matt replied 1 year ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Expert:  Matt replied 1 year ago.

Hi

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