Mechanics

ENGINE HESITATION FROM IDLE

2003 Hyundai Santa Fe

Engine Performance problem
2003 Hyundai Santa Fe 4 cyl Two Wheel Drive Automatic 125000 miles

My car is roughly 6 years old now, and for the last 3 years we would get a slight hesitation after sitting at a light or a stop sign for awhile and then start moving again. It will only hesitate during this situation, no other time will it repeat this.

Parts replaced because of codes
TPS
IAS

Car ran great after about a week after these parts were replaced, but then the symptoms returned. We have noticed on many occasions, if not almost all the time, that the hesitation will happen when you are making a turn and not so much when you go from an idle to drive straight. I hope I can get an answer on this seemingly simple issue with out me having to shell out a lot of money to a dealer to get the answer.

Thanks much,
Frank
Avatar
Hammondfra
May 20, 2009.




Please post the codes for the MIL that warranted the parts replacement. It is necessary for us to know the codes to guide you to perform the proper diagnostic.

Tiny
Zackman
May 20, 2009.
Thanks for the reply.

To be honest I don't remember them (this was about 3 weeks ago).I know they both were a p code in the 100's (maybe p0123 for the TPS) I looked it up and ran what electrical tests from the shop manual I could with out the multi thousand dollar interface computer. TPS high resistance was way high for Hyundai; s perameter on pins 2 and 3 and replaced the sensor per the flow chart.

IAS code was a p01XX, this came about with a run rich bank 1 reading. The whole hesitation issue is in tandem with a huge rough idle at times (dips and raises), when the ambient temp is over 70 degrees and the car is up to operating temps. I checked as a precaution for a fouled plug, they were all fine (changed about 15k ago). IAS read high resistance on pins 2 and 3 replaced per flow chart on out of range resistance readings.

Now I have a new MIL that poped up last night and am waiting for the place to open up so I can get it read. I will post a reply up when I get the results.

But as it is now and what research I have done on this specific issue; it is coming down to either the PCM (will have to go to the dealer to test) or a specific sensor now MAF or MAP on this car. Or maybe a stick of c4 to put it out of it's misery (just kidding)

Thanks again

Tiny
Hammondfra
May 21, 2009.
Okay, just got back from Auto Zone, and the new code I have is DTC P0113 Intake Air temperature Circuit High Voltage.

This comes down to the MAF as the IAT is in the MAF and I will need the High Scan Tool to do all the leg work on diagnostics on it.

Any ideas on this before I venture down and shell out about 100 bones on a diagnostic test?

Edit: P0172 System too Rich (Bank 1) was the rich code I threw.

Tiny
Hammondfra
May 21, 2009.
Okay, no replys yet. So I will go on with any changes today.

MIL codes reset and I put mid grade gas in to try something out.

Even though the codes were reset it still hesitated on take off for about 30 miles. Later today I put 10 bucks of mid grade in and it has yet to hesitate in about 125 miles and runs smoother than it has in months.

So, my question is what the hell? I doubted the gas change, but said what the hell to see and it works? Why and how. Is the knock sensor off and not throwing a code, maybe the engine isn't advancing and retarding enough to compensate while on 87 grade?

Hopefully someone has ran across an issue similar to this.

Thanks
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Tiny
Hammondfra
May 21, 2009.
Your engine is designed to work well with 85 octane. Adding higher octane fuel won't do you much good. It is nice to have a higher octane, but not necessary. Your knock sensor is working just fine. The PCM needs the info from the MAF for air temp and to be able to inject the proper amount of fuel. I'll email you the diagnostic. It is too long for me to cut and paste and still make it look nice. It also comes with a flowchart with probable causes of faulty MAF or PCM.

Tiny
Zackman
May 22, 2009.
I understand about the octane ratings and how they work, that is why I said that I doubted it would make a difference, but I gave it a college go and it paid off for some reason. I know where the IAT code came from and that is why I had it reset to see if it would come back. The MIL hasn't returned and now after 24 hours it is running strong with no hesitations at all.

My car cannot run on 85 octane Hyundai's are designed for 87 octane and I put in 89 for giggles, because I was at my wits end with this car and the minor issues.

I have ideas, but I came here to honestly see if anyone has ever had or has seen an issue like this from a car. Hesitation from idle only no other times will it happen and it has to be above 70 degrees ambient while the vehicle is at operational temps.

I have looked at everything from grounding issues to every sensor that works the intake and output side of the powertrain of this car and nothing makes sense. I read through the " why does my car hesitate" thread on this forum and some of the cases are similar, but not enough to make me want to explore that area in great depth; because it isn't close to the symptoms that I am experiencing with this car.

Tiny
Hammondfra
May 22, 2009.

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