2010 kia forte with the 2.4

200,000 km

Car will randomly act up. It will intermittently not start off the first key cycle. (Even if the car is allowed to prime in the run position)

This is the wife's car and I haven't experienced them, they are VERY intermittent issues.

Her car wouldn't start after running one day. Everything worked (radio lights door alarm) it even would turn over fine. Once booster cables were put on it started right up.

also another part happened when she was doing 120 kmh and shut off, wouldn't fire, plugged in a portable 12v booster and it fired right up.

I scanned it and did some running checks there are no stored/active codes and it's extremely hard to re create the issue. Any ideas?

I did throw a new fuel pump relay in and cleaned the battery terminals. Unfortunately with my limited automotive knowledge I'm not sure where to go without throwing parts at it and that's not really my style.

Take your battery to your local auto parts and have it tested

If you are able, remove the alternator, they can test that too

Check the battery cables that run to the fuse box and starter, make sure connections are tight and clean, clean them and use dialectric grease if needed

I did forget to mention battery is fairly new (-1 yr) but yeah it never hurts to check. I will also do a running voltage check on the alt - is it necessary to remove for bench testing? As really it's either putting out or not?

Also, is fuel injection limited by system voltage? Just curious as to if that's the direction you're going. I had asked her to take a look at her voltgauge but her car doesn't have it. I'm limited for tools as all mine are away where I work. Keep forgetting to pick up a cheap multimeter and it is biting me in the ass

Thanks for your advice. Unfortunately everything is closed today but I'll be taking a closer look at connections

does it happen after filling it up?

The canister on those car tend to fill up with gas then will stop/wont start cuz theyre running too rich

shutting off and wont turn on imediatly could be the crankshaft sensor. they sometimes shut off when the engine gets warm and will work again flawlessly after some cooling time and may not shut down on next warm up.

and ofc like said above messure the alternator

Not directly related it's intermittent no matter on engine temp or fuel level from what I gather



That's definitely crossed my mind especially with it cranking over and not firing.

So she also told me for few days 2 weeks ago the whole car had a slight shake (idle and driving)

She took her car for an oil change and they told her they blew out the air filter (it's filthy) not too long ago as well. I pulled the filter today giving the car a once over and the slimy bastard flipped the air filter upside down and didn't bother cleaning it. Small rocks and butterflies in the intake box. I'll be having a chat with him.


And randomly out of nowhere her fuel consumption increased HUGE. So with the dirty air filter... random stumbling/shaking and increased consumption... MAF sensor perhaps? I am out of town but I told her to get a new air filter asap, run some fuel system treatment and some sensor cleaner.

modern cars can run without maf sensor. to check if its causing problem you can just unplug it and drive. if problems are solved without maf you got a faulty maf sensor.

crank sensor wouldnt increase consumtion. it would just shut off at random moments when car is warm and not fire up till its cooled down a bit, but it doesnt have to shut down so its pretty random fault and thus hard to define and diagnose. but if its faulty and shutting down it will turn over, but wont fire because t cuts off fuel.

This post was edited by Wingman93 on Apr 2 2018 07:48pm

Alrighty then get it scanned and look at fuel trims, you’ll see whats wrong

I removed the battery cables 2 days ago and cleaned the terminals. That same day her fuel mileage went to absolute shit and threw a code for the MAP sensor. I got her to hook up my code reader and clear the code and the CEL hasn't come back but the mileage is still absolute shit.
Also replaced the air filter.

I'm lost. Between this new mileage issue, the odd random dying, and the intermittent no start from first key cycle.

I talked to one of our auto guys and he said the ECM may need to be reflashed in regards to the MAP sensor. When I removed the battery cables there may have been an issue with the keep alive signal.

Going to get her to call the dealership today and see if there are any TSB's or recalls and go from there.. I'm lost

*hopefully in the next few days I've got someone lined up to test her alt output and clean the MAP sensor.

This post was edited by Wimp on Apr 5 2018 09:29am