04 Kia Optima (116,000miles) will drive ok for 20 min. or so (last time 10 miles) I’ll hit a bump, stop, turn a corner, or drive on hills (basically any condition) and it suddenly acts up after a small jerk (engine light comes and goes and I cannot get anyone to read codes correctly). I have to drive with my foot on the gas at stops if it gets really bad and it wont come down from above 40mph unless I break and feels like it wants to stall when trying to accelerate again after stops and difficult to sometimes get past 30/40mph, Once shut off, It has trouble starting, but will start. I have had the PO335Crank shaft position sensor replaced three times, (last time by dealer) New battery, new spark plugs, the throttle body was cleaned, and high octane gas cleaner in the tank as well. Every time I take it in (6 or 7 times, different places), they say “it’s not acting up right now so we don’t know” …I’M CURIOUS ABOUT MY BROKEN FLEXPIPE. NO ONE HAS ADDRESSED THIS ISSUE YET. COULD THIS BE THE CULPRIT? …Thanks so much!
The code needs to be pulled. If the light goes on for any reason, the code should get stored, even if the light goes back out. If the codes are not there, I’m guessing something electrical causing the computer to reset and lose the code. Look at the battery terminals, the alternator wiring, and the main circuit feed to the main fuse box. Voltage spikes caused by bad wiring connections can cause havoc with the large amount of electrocnics in today’s cars.
I agree that you need to get the codes pulled. I do my own since the guys at Auto Zone are usually busy. My old scanner finally died and I haven’t bought a new one yet. Read up on the procedure if you can buy/borrow a scanner. It’s a very easy task. I don’t think the broken flex pipe has anything to do with your malfunction. BTW…get that broken flex piped replaced because carbon monoxide is a very nasty fellow.
Which flex pipe? Could you be refering to the black pipe from the air filter to the throttle?
I didn’t know there were more than one flexpipe. I know it’s up front, that’s it. Nobody has looked at it. They only say it’s the flex pipe by hearing the noise it makes like a loud muffler/lawn mower.
Apparently it is the exhaust flex pipe causing the noise which may be leaking due to restriction in the exhaust system. There are seeming contradictions in the symptoms that leave me in the dark though. When there is difficulty accelerating to 40 it seems unusual that you must brake to reduce the speed from 40.
A restriction in the exhaust could cause the flex pipe to leak noisily and reduce power and make the car unable to accelerate. If the leak becomes severe enough some power could be restored and the noise would worsen.
A good independent full service shop that welcomes Korean vehicles should be able to diagnose your problems and give you a fair estimate on the needed repairs. I strongly suggest that you ask around for recommendations for a good shop.
@Rod Knox
"There are seeming contradictions in the symptoms that leave me in the dark though. When there is difficulty accelerating to 40 it seems unusual that you must brake to reduce the speed from 40. "
__After a stop, sometimes it is difficult to get back to, or past 30/40mph. but then after finally going 40 or higher it won’t idle down when accelerator is released. Sometimes at stops it feels like it wants to stall and it stutters taking off. I keep my foot on the gas at stops sometimes because of it.
__I did get something fixed the other day, some bolt or bushing in the back that I was told by a major auto place was the sway bar bouncing around back there. Since then, the engine light did stay on after shutting the car off a few times. Prior to this fix tho, when I noticed a bump something would hit in the back (sounding like it hit my gas tank) and my engine light would flicker and the trouble would begin again.
__I just bought the car last August. …Car sold as is so I can’t lemon law it. Took it to have it looked over before buying it by this place that said it needed a sway bar replaced. okay…It drove great…
__The only OTHER THING I NOTICED was the car door locks locked up on me when I grabbed the outside handle, while running in the winter before all of this happened and the flex pipe started to make noise about just before this (month or so).
__Car is at another mechanic now. We’ll see if he can retrieve codes. Just frustrated, low income single mom took my savings and flushed them! I just hope someone can figure it out. This is my last attempt.
Your symptoms suggest the engine has an intermittent misfire, this will cause the check engine light to flash but must occur on two consecutive trips to store the fault.
__“After a stop, sometimes it is difficult to get back to, or past 30/40mph. but then after finally going 40 or higher it won’t idle down when accelerator is released. Sometimes at stops it feels like it wants to stall and it stutters taking off. I keep my foot on the gas at stops sometimes because of it”…
a bad TPS perhaps?
__"I did get something fixed the other day, some bolt or bushing in the back that I was told by a major auto place was the sway bar bouncing around back there. Since then, the engine light did stay on after shutting the car off a few times. Prior to this fix tho, when I noticed a bump something would hit in the back (sounding like it hit my gas tank) and my engine light would flicker and the trouble would begin again."
IMHO two unrelated problems. The banging sounds like a busted sway bar link. The other like an intermittent connection. Perhaps to the fuel pump??
__"The only OTHER THING I NOTICED was the car door locks locked up on me when I grabbed the outside handle, while running in the winter before all of this happened and the flex pipe started to make noise about just before this (month or so)."
Again, two unrelated problems… HOWEVER, if a battery cable has a bum connection or the battery has a loose post, both the doorlock problem and the CEL light flickering when going over bumps could be both from the same cause…
PostScript: nice summary Jo. 
@the same mountainbike
Thank you.
(TPS)? Stands for: Throttle Position Sensor?
That sounds like a real possibility. I just hope codes show up this time for this last place. I’m putting too much money in guesses at the moment due to no codes.
I agree with the battery cable connection.
I tried to tell the 2nd guy that changed my CSPsensor. I had to go back after all of my lights except one headlight and one backlight mysteriously blew out while driving home. I went back right away and they took the battery out to replace the one headlight and I noticed a delay in my radio and air/heat afterwards and that it runs a little harder now when I turn the air on. “Oh that’s normal, all cars do that”.
…But, the problem driving presented itself once more a day or two after again…
Seems every time I get something fixed, spark plugs, battery, 3xCSPSensor, ect… it runs really good (sometimes better) for a day or two, then the symptoms start all over again. But maybe because I’m not driving for 30min at a time.
Thanks everyone for your responses. Appreciate them greatly.
Okay, just got a call:
Codes are P1372 (camshaft sensor) and P0335 (crankshaft not going to replace again btw!)
They say they need to take off the valve cover to check $200-300. They hear a noise rattling around in the engine. Maybe something is not lined up right, could be simple, like belts or expensive like motor.
"I had to go back after all of my lights except one headlight and one backlight mysteriously blew out while driving home"
Try having your charging system checked. All of the electrical glitches could be a bad voltage regulator in the alternator.
"I noticed a delay in my radio and air/heat afterwards and that it runs a little harder now when I turn the air on. “Oh that’s normal, all cars do that”."
He’s right. When you turn the AC on, it engages a refrigerant compressor driven directly off of the crankshaft. That places a load on the crankshaft and loads down the engine, making it work harder. Your ECU (computer) compensates by increasing the idle a bit to keep the engine idling.
I can’t speak to all of the issues discussed here, but modern engines are designed to be air tight contraptions. Everything that comes in is only supposed to arrive by a certain route, and everything that goes out is supposed to leave by a certain route. When either of those principles are violated, it can confuse the computer and the engine may run poorly. So before investing time in the crank and cam sensor investigations, suggest to get the exhaust system repaired and in good order first.
I think it’s time to switch mechanics. 3 crank shaft position sensors and they have not investigated other sources that could trigger this PO335 code.
I think the reluctor ring may have had a tooth knocked out from road debris or more likely, the key that keeps it lined up on the crank shaft may have sheared off. If the key is sheared off the harmonic ballancer could float a few degrees as you accelerate and then float back when you leave your foot off the gas.
Most times they will get so out of time that the engine will not start, but I have seen a few that only float a couple of degrees and that could cause the rough running.
The P1372 is a faulty right front wheel speed sensor. Nothing to do with the performance issues that you are having. Because you have this code the ABS light should also be illuminated after you start the car.
The flex pipe issue is not related to the performance issues that you have, but I would have it fixed. I would hold off on that problem until the poor running issue is fixed. Unless it gets so loud that the mechanic can no long hear problems over the noise.
Yosemite