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Discussion Starter · #1 ·
Hi all - 2003 Santa Fe GLS 3.5l with 170k.

Been working OK up until about 2 months ago when I would notice a brief hesitation every once in a great while when driving. It became hard to start - would crank well but just took about 5 seconds to finally start. Recently, I was on the highway and it jerked at about 65mph but did not cut off. Once when I was at a traffic light, it shut off completely but started right back up again. I was convinced that it was a crank or cam position sensor as I had dealt with a similar issue with another car years ago. It also seems to start right away when the temps are in the single digits - when they get higher than 25 or so, hard to start again.

I bought a new crankshaft position sensor because all the posts I've read point to that being the problem given the symptoms. I haven't installed it yet - still looking into this and wondering where it is! I'm thinking that it might be more fuel-related now though because after I started my car after work yesterday (it went all day without being started) it was hard to start but this time it was if I hadn't started it in 3 weeks. It kind of sputtered until I gave it the gas enough where it would settle out. Fuel pressure regulator? I hadn't thought it would be fuel-related (pump, pressure regulator) because 99% of the time, the car works just fine.

Would like any insight on the most likely cause. No check engine light on either which I actually hoped would come on to point me in the direction of the fix.

Thanks in advance! B)
 

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Hi all - 2003 Santa Fe GLS 3.5l with 170k.

Been working OK up until about 2 months ago when I would notice a brief hesitation every once in a great while when driving. It became hard to start - would crank well but just took about 5 seconds to finally start. Recently, I was on the highway and it jerked at about 65mph but did not cut off. Once when I was at a traffic light, it shut off completely but started right back up again. I was convinced that it was a crank or cam position sensor as I had dealt with a similar issue with another car years ago. It also seems to start right away when the temps are in the single digits - when they get higher than 25 or so, hard to start again.

I bought a new crankshaft position sensor because all the posts I've read point to that being the problem given the symptoms. I haven't installed it yet - still looking into this and wondering where it is! I'm thinking that it might be more fuel-related now though because after I started my car after work yesterday (it went all day without being started) it was hard to start but this time it was if I hadn't started it in 3 weeks. It kind of sputtered until I gave it the gas enough where it would settle out. Fuel pressure regulator? I hadn't thought it would be fuel-related (pump, pressure regulator) because 99% of the time, the car works just fine.

Would like any insight on the most likely cause. No check engine light on either which I actually hoped would come on to point me in the direction of the fix.

Thanks in advance! B)
The top part of this post is a classic description of a CPS going bad. The strange part of your post is that you have a 2.7 v6 listed as your car in the information area and yet have a 3.5 listed in your post as your car. Which do you have? The CPS is located in different areas of your car depending on which engine you have. The 2.7 is located above your starter and not excessively hard to get to. The 3.5 is much harder to get to and is almost like changing your timing belt-hard. You could have two different problems or the CPS has finally bit the dust. If it gets bad enough to not start it should finally set a P0335 code. If may or not set the code for just the classic jerking you get with a bad CPS.
 

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Discussion Starter · #4 ·
OK, here's an update. I'd like to point out exactly where the sensor is on this 2.7l model because I haven't found a good explanation on this site or anywhere else for that matter and the Haynes manual is useless. On the 2.7l model, the crankshaft position sensor is located on the bottom of the engine. It's only accessible from underneath the car. I ended up removing the starter shield to gain better access. The sensor is above the starter tucked in a bit and virtually not visible from where you'd be working. If you get a mirror and a flashlight, you'll see it. The other option is to possibly remove the starter but I didn't want to open up that can of worms. For those of you who are brave, you'd likely have a simple replacement of the sensor. Just remember to remove the (-) battery cable before doing any work around the starter. Now for the update.

I removed the old part and it looked just like what others have described in this forum - damaged wire insulation resulting in bare wires. Put in the new part after some time trying to blindly find the alignment of the sensor mounting hole and the engine threaded hole.

Here are the symptoms prior to changing the sensor:
- Hard to start most times when car had sit for more than 20 min or so, all day or overnight.
- Starts right up afterwards if you're just running into the store or getting gas.
- Starts right up when temps were sub 20 degrees even after sitting all night.
- Hesitated (jerked) on the highway once in a great while.
- Stalled at a stoplight one day after driving for 30 min. Started right up again.
- No CEL.

After replacing the sensor and starting the car, the car started quickly, right away - almost like I had replaced the battery. Drove the car to the store that night, was in about 45 minutes and the car was sem-hard to start again. Since then, it has behaved pretty much just like it did before I replaced the sensor only I haven't yet felt that jerking on the highway and I don't really expect to.

I was only semi-confident that the replacement of the sensor would solve this issue and it looks like I was right. I personally think there is a fuel pressure problem at this point. I don't get any hesitation while driving though so I think the fuel pump/filter is OK.

Any other ideas? TIA
 

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OK, here's an update. I'd like to point out exactly where the sensor is on this 2.7l model because I haven't found a good explanation on this site or anywhere else for that matter and the Haynes manual is useless. On the 2.7l model, the crankshaft position sensor is located on the bottom of the engine. It's only accessible from underneath the car. I ended up removing the starter shield to gain better access. The sensor is above the starter tucked in a bit and virtually not visible from where you'd be working. If you get a mirror and a flashlight, you'll see it. The other option is to possibly remove the starter but I didn't want to open up that can of worms. For those of you who are brave, you'd likely have a simple replacement of the sensor. Just remember to remove the (-) battery cable before doing any work around the starter. Now for the update.

I removed the old part and it looked just like what others have described in this forum - damaged wire insulation resulting in bare wires. Put in the new part after some time trying to blindly find the alignment of the sensor mounting hole and the engine threaded hole.

Here are the symptoms prior to changing the sensor:
- Hard to start most times when car had sit for more than 20 min or so, all day or overnight.
- Starts right up afterwards if you're just running into the store or getting gas.
- Starts right up when temps were sub 20 degrees even after sitting all night.
- Hesitated (jerked) on the highway once in a great while.
- Stalled at a stoplight one day after driving for 30 min. Started right up again.
- No CEL.

After replacing the sensor and starting the car, the car started quickly, right away - almost like I had replaced the battery. Drove the car to the store that night, was in about 45 minutes and the car was sem-hard to start again. Since then, it has behaved pretty much just like it did before I replaced the sensor only I haven't yet felt that jerking on the highway and I don't really expect to.

I was only semi-confident that the replacement of the sensor would solve this issue and it looks like I was right. I personally think there is a fuel pressure problem at this point. I don't get any hesitation while driving though so I think the fuel pump/filter is OK.

Any other ideas? TIA
You've fixed the jerking at highway speeds and the dying at stop signs. Those two symptoms were the bad CPS. The hard to start is another problem.
 

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Discussion Starter · #6 ·
Yes, I'm pretty confident of that. I've read a fuel pressure test procedure on this forum that seems pretty involved. I'll wait until summer to maybe attempt that.

It was pretty odd though, when I first started the car after the sensor replacement, it fired right up immediately whereas normally, given the temperature conditions and sit time, it would have been a hard start. I first thought that maybe I was wrong and the hard starts really were caused by the bad sensor but when I started it, it was also right after I had secured the (-) battery terminal. I wouldn't think that a dirty connection to the battery would be the culprit of a hard start but who knows? I might clean the terminals and connections anyway. Even so, if it was a loose/corroded battery connection, I would think my battery warning light would come on due to inefficient charging.

Back to the drawing board.
 

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OK
- Hesitated (jerked) on the highway once in a great while.

- Stalled at a stoplight one day after driving for 30 min. Started right up again.

- No CEL.



Any other ideas? TIA
Yes.. Replace the original grey plastic TPS with the current part (black plastic)... Get a new gasket for the ISC, less than $1, as the original may crack/break when remove ISC to get at TPS screws.

OLD PART -
 

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Discussion Starter · #8 ·
Thank You. Excuse my ignorance. I gather TPS is throttle position sensor. ISC is what exactly?
 

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Discussion Starter · #10 ·
Update:
I did not replace the TPS or ISC. I wanted to investigate more before I spent the money on it. Last night, while at the drive-thru at McDonald's it stalled on me. Started right back up again but I think I'm back to the drawing board again. No CEL. The weather in New England has been cold - 10 degrees in the morning. When it's this cold the car starts right up. Any warmer than that and it's a hard start. So, while the sensor needed replacing due to the corroded insulation on the wires, it seems not to have helped my situation.
 

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If you want to know if the TPS is bad, just unplug it. The ecu will automatically calculated expected TP and adjust accordingly. It won't stall or buck, just accelerate slow. Don't smash the gas pedal down or you'll choke it.
 

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I suppose it will calculate according the camshaft position sensor then, so it is not totally lost in timing.
But it seems the cranckshaft sensor is the most important one to go by.
Greets,
Paul
 

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Discussion Starter · #13 ·
@jsinton - how will I know if the TPS is bad if the engine will compensate? Or if it is bad, will there be no change in idle? Do I do this while the engine is running or stop it first?
 

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Discussion Starter · #14 ·
Went for about a week straight starting right up with no problems then back to hard starting for the past 2 weeks. I don't know what the deal is with this thing.
 

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Discussion Starter · #15 ·
Great. Well, I changed my oil yesterday, went to the store and the car almost cut off on me as I was pulling into the parking lot. As I pulled into a parking space, I was about to turn the car off, when it did it for me - died. It was hard to start but it started back up and finally the MIL light came on and I read a crank position sensor circuit as being the problem. I don't know why though, as a new sensor was installed a few months ago. I'm beginning to really hate this car. Why wouldn't it throw this code before? Why now with a 3 month old (aftermarket) sensor installed???
 

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Discussion Starter · #17 ·
Yeah, I thought about that. Tough thing to do with all the harnesses tied together under wraps and inaccessible, etc...
 

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Have you changed the cam sensor? Hard starting, long cranking is usually a sign of somthing wrong here. The ECU will take a few crank rotations and guesses where the cams are. When it starts though it know from torque calculations and crank sensors.

It's been my experience that when the crank sensor is bad it just won't start, unless it s the shielding on the wire gone or damaged.
 

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hello, check the eng. coolant sensor when they open the pcm thinks its -40 degrees and it will stall,hard to restart,but will start in very cold weather.if the socket is loose it wont allwaya cause a pcm code,
 
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