Car studders when accelerating slowly or going uphill. (Only when engine is hot)


It’s a 1.6 gdi engine. It stutters when it accelerates slowly or going uphill. If I floor it it stops. Could this be a fuel filter or low pressure pump? I think the cam follower is bad, but read it doesn’t show symptoms before failing. Is this true? Could it be the follower? Thanks.

What year, how many miles? What maintenance has or not been done on the car. the more you tell us the better our answer will be

2012 with around 200k.
Has new plugs, coils, air filter, crank sensor, coolant temp sensor.
It was regularly maintained till 170k. After that I’m not sure.

Jameson , is this the 2012 Kia that gets poor fuel mileage plus the other problems in your other threads . Too many threads about the same probmatic vehicle just gets you more guesses.

Frankly it sounds like you need to just let a shop fix this thing and be done with it.

It is.
I would, but I just graduated and I’m completely broke. I’m trying to find a job.

I did get the gas millage way up after replacing the coolant sensor and replacing the valves.

A Kia Rio with 200kand all it does is stutter? I’d say you are lucky it still runs.

You didn’t say if the check engine light is on. This isn’t your first post… c’mon, what are the codes if any?

If no codes, I’d guess the compression on all cylinders is low because the rings are worn out. Run a compression test as a first step.

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There are no codes

Sounds like spark should be good. You might want to check fuel pressures. Compression test as @Mustangman suggested. Then have it scanned for fuel trims to check injector performance. Also a thorough check for vacuum leaks.

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Ignition components like the crank position sensor can fail when hot but work fine before that.

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Well I did the compression test.

190 170 182 189 Dry
193 200 188 190 Wet

How worried should I be with that number 2 cylinder?

Seems you’re losing compression through the rings on number 2. But with that much compression I wouldn’t think there would be a miss. Maybe under a load the conditions could change causing a miss. maybe someone with more experience here could chime in and tell you what effects the loss of compression loss at the rings here could cause.

Or is there no check engine light?

Does the light work?

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Good ideas above. The first thing I thought of w/those symptoms is pre-ignition caused possibly by engine overheating. Are there any cooling system problems? Air pockets in the coolant could cause this sort of problem.

Also, cam follower problems could cause something like this. And they might be intermittent and heat related. I wouldn’t count on the theory you mentioned that a cam follower will either fail completely or work ok, and there’s nothing in-between.

Thanks. I haven’t noticed any problems with the cooling. I’ll see if I can bleed anymore air out when my engine cools off.

After I did the compression check I checked the gap on the plugs again. I cleaned them off as well. Number two plug was dirty. I put them back on and went on a long drive and the car ran like new. I went on a longish drive today and the the problem started again after about half an hour in.

There was a huge difference after reinstalling the clean plugs. It has come back, but not nearly as bad, after about 100 miles of driving.

check that plug again. if its messed up again you have a problem with that cylinder.


If the #2 plug keeps fouling, that tells you the engine is just about at the end of its life.

I’d suggest switching to the spark plug you use in #2 to one or 2 steps hotter sparkplug to try and burn off the oil deposits so you don’t have to clean the plug weekly. I’d also try a can of Restore in the oil to maybe get a little more life out of the car. Can’t hurt, might help.