Hyundai Forums banner
1 - 20 of 23 Posts

·
Registered
Joined
·
90 Posts
Discussion Starter · #1 ·
Hi folks. Just bought my '05 Sonata with the 2.4 and auto trans--137k miles. I briefly wondered why every time I went to look at it, the engine was already warmed up...more about that later*

Everything was fine the first day, car ran well except for an occasional 'burp' or 'hiccup' when idling in drive at traffic lights. I figured it would eventually get worse and I'd fix it. Well, the second day, started it from cold, it kicked right off and then as I was idling in the driveway in gear, it just...stopped. I eventually got it to restart and got half a block before it stopped again. Eventually it threw a code for the above (forget the exact numeric code) crankshaft sensor, as many others have.

Okay, researching the issue here, I repeatedly see advice to replace the sensor, but several have mentioned bad wiring as a possible cause. One video on the subject shows the wires frayed inside the jacket where they are attached to the power steering pump...pinched by the zip tie.

*Here's the kicker though: once the coolant temp reaches 170 F, the problem disappears. I can drive the car all day and it doesn't shut off. Even below 170, as long as the car's been driven lately (doesn't cool to ambient temp), it's fine except for the occasional burp at idle. I'm not a 'get there early' kind of guy, and I don't have time for multiple restarts on the way to work.

Any advice beyond just replace the sensor?
 

·
Registered
Joined
·
1,342 Posts
Replacing the sensor is your best bet.
The insulation on the wiring harness that runs from the harness plug near the firewall, over the top of the valve cover near the timing belt, down the engine behind the power steering pump bracket is well known for becoming frayed and just falling off.
Also, the sensor itself may be going bad so it only works well when warm since the internals have expanded and are then making proper contact.

You may as well change your timing belt while you're at it since the belt has to come off to get to the CPS.

Just did mine about a month ago on my '05 Optima. (Same exact engine and trans as the Sonata)
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #3 ·
A shame. I should have questioned the warmup before inspection thing. Now this very good deal will turn out to be just average. I looked at the procedure for changing the belt, and I'm afraid I don't have the place or the time for it.

Still, the car is very nice with decent 20' finish and a nice interior. Runs great (except when it doesn't). I suppose I should have factored in the cost of a timing belt change anyway when buying.
 

·
Registered
Joined
·
1,342 Posts
When was the belt last changed?
And did the seller provide proof that it was done?
If you have no proof that the timing belt was done I would change it as having the timing belt let go will destroy the engine.
Pistons will slam into valves and it will be total mayhem internally.
Mine was at 189k and it was just under the 60k maintenance interval for the timing belt so I did the timing belt, water pump, CPS, and valve stem seals.
She still runs like a champ so I'm hoping to get at least another 60k out of her before I get rid of it or it dies.
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #5 ·
Well, it's all moot now. The car won't start at all now. I only put about 50 miles on it.

Does anyone have a link to the discussion I believe I saw here, which details the meter readings on the plug at the far end of the crankshaft sensor? It would be helpful at this point to stick a meter on those connections to verify the sensor issue before I have it towed.....
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
18,613 Posts
I assume it cranks and just wont fire up?

If so, check to see if the CEL illuminated when you turn the ignition on.
Check to see if the ignition coils are producing a spark.
Check to see if the fuel pump is being switched on DURING CRANK.
If you have a CEL but no spark and the fuel pump isn't being switched on, that kinda points to a crank sensor problem.

To test the fuel pump supply, check for voltage at the pump test connector under the dashboard next to the OBD connector....see below.
You should have 9~10V on the pump test terminal DURING CRANK.

To test the crank sensor wiring, disconnect the sensor and measure the voltage on each of the 3 terminals of the sensor's harness connector.
You should have one terminal with 12V (power supply), one with approx 5V (signal) and one with 0V (ground).
It's always a good idea to connect your meter between battery positive and the ground terminal and confirm you get 12V.

Scottie.


Pump Test - Terminal #9
 

Attachments

·
Registered
Joined
·
90 Posts
Discussion Starter · #7 ·
I can hear the pump working. The OBD is throwing a crank sensor code. I can test the computer side of the connector. It's the engine side I want to test. There are three wires from what I've read. One is ground, the other supply voltage and the last one is the data wire.

I want to know if there's a way to meter the sensor side of that plug to determine if there is a wiring fault between there and the sensor. It's a common fault, but the wiring is pretty inaccessible when it disappears behind the power steering pump.
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
18,613 Posts
If the pump is running DURING CRANK, that kinda suggests the crank sensor must be working. If the sensor wasn't working the PCM wouldn't know the engine was turning, so it wouldn't switch the pump on.

AFAIK, there aren't any resistance checks for the type of crank sensor fitted to your engine (Hall Effect sensor). Hyundai certainly don't publish any resistance values for it. So you could measure it's resistance but you'd have no way of knowing whether the values were right or wrong.
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #9 ·
I'd be looking for shorts or opens. One of the places reported to be an issue is where the cable is zipped to the bracket. If I found one, I'd pull the water pump and check the cable. If I found it there, there would then be no immediate need to pull the timing covers.

Of course, the wiring fault could be inside the cover, so no guarantees; but it would be a useful check...if only I knew the expected parameters. Does a Hall-effect sensor have resistance, or is it completely open (or a dead short) when not energized? Which connector pins carry the ground, signal ground, and sensor output?
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
18,613 Posts
Does a Hall-effect sensor have resistance, or is it completely open (or a dead short) when not energized?
Well, it really must have resistance, but what that resistance should be I have no idea.

Just a thought...the cam sensor is a Hall sensor too so you could try measuring the resistance of the cam sensor (after IDing which terminal is which) then compare your cam sensor resistance to the crank sensor. Electrically they are both basically the same sensor so I'd expect them both show similar resistance.

These sensors have semiconductors inside so you'll probably get different resistance values across any two pins depending on which way round you connect the meter probes. So you need to be careful what probe you connect to which terminal on each sensor when comparing values.

jakdedert said:
Which connector pins carry the ground, signal ground, and sensor output?
As I explained before, the sensor has a 12V power supply, a ground and a signal output. I already explained how to determine which terminal is which just by measuring the voltages on the harness connector.
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #11 ·
Well, it really must have resistance, but what that resistance should be I have no idea.

Just a thought...the cam sensor is a Hall sensor too so you could try measuring the resistance of the cam sensor (after IDing which terminal is which) then compare your cam sensor resistance to the crank sensor. Electrically they are both basically the same sensor so I'd expect them both show similar resistance.

These sensors have semiconductors inside so you'll probably get different resistance values across any two pins depending on which way round you connect the meter probes. So you need to be careful what probe you connect to which terminal on each sensor when comparing values.


As I explained before, the sensor has a 12V power supply, a ground and a signal output. I already explained how to determine which terminal is which just by measuring the voltages on the harness connector.
All very good suggestions. I hadn't thought of ID'ing the pins from the computer end. I'll let you know how that all works out...unless I get disgusted and just have it towed to a shop for timing belt replacement (along with CKP R&R).
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #13 ·
I have a spare CPS that I will send you if you cover the cost of shipping.
Let me know.
I'm in So Cal so it would just be shipping to wherever you are.
Nashville, I presume?
That would be a boon, thank you. Cost of a new one is anywhere from $20--$100, with around $50 being the average. I have to deal with the issue this week.

You accept Paypal?
 

·
Registered
Joined
·
1,342 Posts
And yes, Nashville
I have Paypal account.
Send me a PM with your address and I will get shipping costs from So Cal to Nashville and PM you what shipping will be.
I'll send it out tomorrow when I get your address.

I ordered one to replace as preventative maintenance but misplaced it when the wife moved things around in the garage.
Ordered another one so I could get my timing belt service done and found it after I had already installed the new one.
I'd rather it go to someone that could use it than have it here collecting dust.

The CPS came from Rockauto originally.
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #17 ·
To wrap up this chapter in the story:

I found a mechanic in my immediate neighborhood (two blocks away...downhill) who was willing to install parts I sourced, and just charge me labor. Thanks to Grady, I didn't have to get a new sensor. I still owe him postage. The bulk of the parts (new seals, water pump, timing belts, tensioners, accessory drive belts) came from Rockauto and cost me about $175. I took the car in on Monday (it started), got it back on Wednesday, and paid $300 after shop fees, taxes etc. The car always starts now, and never dies. I'm very pleased with the experience...and I'm almost never pleased with mechanics.

But to restate: the cause of the problem was indeed the Crankshaft Angle--or Position--Sensor

All that said; it's still not all smooth sailing. While the car always starts, it sometimes takes a couple cranks. It has a tendency to stumble after stopping in gear. The initial 'cough' that it occasionally also does at stoplights hasn't changed.

Worse yet, the transmission seems a little off. Most obviously, it occasionally fails to engage in reverse, then does so after an indeterminate amount of time, with a lurch. Only happens now and then, but heaven help if you just drop it in reverse and hit the gas. Then it might engage with a BANG!...or not at all. It also lurches if you shift manually to 1st at any speed. When driving it seems the transmission seems to hunt for a gear a little too often when coasting. It's constantly dropping in and out of 4th.

Nevertheless, while I still don't trust the car to take a trip, it's been pretty good for daily driving...and I just realized I have a headlight out. :(
 

·
Registered
Joined
·
1,342 Posts
First off, glad to hear that the CPS and your other parts got the engine portion mostly sorted out.
The stumbling is so random that it will be tough to track down.



As for the trans, have you dumped the fluid and put in some fresh synthetic fluid?
Hopefully the trans isn't too far gone and swapping in some fresh fluid will do the trick.
In my '05 I use Valvoline Max Life full synthetic in the trans and it works great.
 

·
Registered
Joined
·
90 Posts
Discussion Starter · #19 ·
Done nothing yet. The hiccup, and more annoyingly the hesitation and stumbling, are even more important. Maybe related? Along with trans flush, I think I'll pull the plugs and maybe Seafoam the injectors.

Since yesterday a couple other things occurred: I filled the tank for the second time and mpg was something just above 14. Perhaps I didn't do that right. I'll pay more attention this time around.

Lastly, the air conditioner took a large piss on the passenger floor. I know that's always a clogged drain, but where is it on the '05? How do I get to it?

I bought the car to get back and forth to work in comfort, and it's been a boon in that respect...so I can't afford to lose the AC of all things.
 

·
Registered
Joined
·
2 Posts
Hey I have similar issue. 2001 sonata. No spark. Voltage at coils fine. Voltage at crank fine. When I unplug and rep lug crank sensor I hear fuel pump and injector activate. Is there anything else that would cause a no spark condition?
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top