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Matt
Matt, Mechanical Engineer
Category: Hyundai
Satisfied Customers: 20600
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My 2010 petrol ix35 has a jerking problem after 4000rpm, I

Customer Question

My 2010 petrol ix35 has a jerking problem after 4000rpm, I have changed the fuel filter, then changed the fuel pump and it's still jerking. Advise please x
Submitted: 10 months ago.
Category: Hyundai
Expert:  Matt replied 10 months 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. 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 faulty Air 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 leaks its 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
Customer: replied 10 months ago.
Hi Matt, the engine runs perfectly and not revving up, nor is there a hissing noise. I live in Zambia so a good mechanic is few and far between and the Hyundai dealership rubbish and expensive. It jerks occasionally and stops when I get up to speed, it's automatic
Expert:  Matt replied 10 months ago.
Hello thanks for the extra informationas its an auto its well worth checking some transmisson basics I'd take a look at the colour of the transmission oil it should be a dark red colour if its black then its needs changing together with its oil filter. Also check its level with the gearbox warm and just after you've moved the selector through all the positions leaving it for a few seconds in each one and then back to park. You can top up the box through the side fill plug if required and make sure you use the correct oil for your car as the fluids are not all the same. Some manufacturers recommended a change of the type of fluid - Speak to the local dealer and parts dept - they will advise you on the updated fluid to use.. If that’s all OK then check all the electrical connections of the gearbox, remove each connector in turn and spray with contact cleaner. Check that the wiring to the gearbox is in good condition with no chafing or frayed wire If this is OK then check the selector lever linkage / cable under the car for any broken parts and or missing bolts as if this is coming adrift then it can rub on the car body or just bind up Then - you should top up if low and re try it - or, if its level is ok - and condition is ok - then the next step is to drain it off - open it up and clean the filters inside -- refill and retry it..
Expert:  Matt replied 10 months ago.
Hi
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