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Matt, Engineer
Category: Kia
Satisfied Customers: 20384
Experience:  Mechanical Engineer BEng Hons22 years experience in car engine industry, 10 years in formula 1
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Kia Rio: 2002 Kia Rio 1.5 rusn rough under load

Customer Question

2002 Kia Rio 1.5 rusn rough under load
Submitted: 5 months ago.
Category: Kia
Customer: replied 5 months ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Matt replied 5 months ago.
Hello this sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank. If the connections to the pump are corroded or damaged then the pump could stop at any time or could notbe running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,Ideally measure the pressure at the injectors and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.
Customer: replied 5 months ago.
How do I do that? There is no port to hook up the pressure tester.
Customer: replied 5 months ago.
I figured out the fuel pressure. It is ok. This thing raises the idle when I put it in gear or turn on the AC, but a second later the idle drops and it starts running rough again. And it has little power running down the road.
Expert:  Matt replied 5 months ago.
OK thanks for the extra infoThis 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.

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