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Matt
Matt, Mechanical Engineer
Category: Toyota
Satisfied Customers: 20602
Experience:  BEng, Repaired my own cars and others for 20 years, worked in Formula 1 for 10 years
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Will sart idle high, will run, then jerk seconds, apply

Customer Question

will sart idle high, will run, then jerk for few seconds, apply gas, runs, loosss of vacuum brake become hard
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Toyota. The Toyota Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: some time runs great, have changeds plugs, fuel filer, air filers, has169k
JA: Are you hoping to fix this yourself?
Customer: es
JA: Is there anything else the Toyota Mechanic should be aware of about your Toyota?
Customer: yes
JA: What else should I tell the Toyota Mechanic?
Customer: ?
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Toyota Mechanic about your situation and then connect you two.
Submitted: 7 months ago.
Category: Toyota
Expert:  Kurt Kennedy replied 7 months ago.
Sorry to hear you are having issues with your toyota. To get things started, can I please have the year, model and engine size in the vehicle we are talking about please?Thank you
Expert:  Matt replied 7 months ago.
Helloyou don't say what car this is but 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 flattenedpiece 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. It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.if the engine condition is the same then chances are the meter or the connection to it is faultyAir leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them. This leads them to be quite intermittent in the case of mild leaksits also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue On no account touch the sensor wires with anything physical as they are extremely fragile
Expert:  Matt replied 7 months ago.
Hido you still need help?Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

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