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Really need some advice as I am at my wits end. I brought a used 2005 Sonata over a year ago. I got the car for a pretty good price but there was no service history. I knew there were some gremlins in it and I’ve worked all of them out except one. Very intermittently it will exhibit a crank no start condition. This condition will last for a few minutes. Note that I have never been stranded. The car has always eventually started. It typically requires multiple starting attempts and extended crank time. Once started when this happens it seems to idle very poorly but corrects itself within a few seconds. Other than this very intermittent event It idles, accelerates and runs normally. It has never stalled on me. I can literally go for months without this happening. The check engine light is off and I have never found any codes no matter how many times I scan before during or after the incidents. It seems to happen most after a long drive and the car is then parked for about a half-hour or so. If I turn the engine off no matter how long it has been running it will always immediately restart without issue. Over the course of the last year I have done some work to the car since I did not have any history and in some cases because I had some spare parts lying around. I have replaced the timing belt, fuel pump, spark plugs, and crank position sensor, idle air control valve, MAF sensor. All parts this work were new. I also swapped the existing engine coolant temp sensor with another one that I had that was used (both tested OK). I did all this work myself. The last time I had the crank no start condition I had a lemur blue driver monitor on it and captured some data:
“Time(s)”,”Fuel System Status()”,”Engine Coolant Temperature(°C)”,”Engine Coolant Temperature(°F)”,”Short Term Fuel Trim Bank 1(%)”,”Long Term Fuel Trim Bank 1(%)”,”Short Term Fuel Trim Bank 2(%)”,”Long Term Fuel Trim Bank 2(%)”,”Engine RPM(rpm)”
The data is in the attached CSV file. What I note from this data is that engine coolant temp was 189 degrees F. This is within the normal range. The RPM data shows engine rotation during the no start period. The engine only cooled 2 degrees when it did start. I really think this condition is heat related by I have no idea how to test the theory since it is so intermittent and by the time I can get around to doing anything whatever is causing the problem will no longer exist and the car will start. My other thought is that the issue is tied to the car being in open loop at cranking time and something is wrong with that. It seems like that would explain the initial rough idling but why wouldn’t this condition exist all the time?? At any rate I readily admit that I am stumped. I’ve been to the Hyundai forum with this and had some suggestions but nothing has panned out yet. Figured I would come to this forum and see if you guys had any thoughts on this. Thanks!
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Most vehicles use open loop when starting and only start using fuel trims once the engine stabilizes. I would be concerned with this. Possibly an issue with the EVAP purge valve sticking open. This is a normally closed valve that opens when energized to purge the charcoal canister of gasoline vapors. If stuck open it could cause the symptoms you are describing. Also maybe the but unlikely that either the fuel pump check valve is allowing the fuel in the line to drain back down and creating a hard start but that would not cause it to run rough at start up. you could check this by putting a fuel pressure gauge on and seeing if the fuel pressure drops rapidly after you shut the engine off.
Hi ArmedsouthernER – Thank you for your response. I forgot to mention in my original post that within the last year I also replaced the purge control valve, the fuel pressure regulator, and the car battery. The purge valve sticking is a pretty common issue with my vintage Sonata. I’ve given lots of thought to the fuel pump. I did replace the pump itself (with a bosch pump) and the strainer (with an airtex) but I did not replace the entire fuel pump module. I sometimes kick myself for not having replaced the whole module but my understanding is that the check valve is in the pump itself, right? If that is the case then the check valve is new as well. Also my monitor does show open loop at startup and closed loop within a few seconds so this seems to be working normally. Unfortunately my vintage Sonata does not have a schraeder valve on the fuel rail so you have to get into some plumbing to check fuel pressure and I do not have a fuel pressure gauge at the moment anyway. If the fuel pressure drops rapidly after engine shut off then I would think this would cause the problem to appear consistently. I will do some research on fuel pressure gauges. Thanks again for your input.
Yes the open loop thing is normal. It depends on the design of the fuel pump as to where the check valve is but as you stated and as I stated the likely hood of this being the cause is slim. Have you ever seen scan data when the no start happens to see if you do indeed have an rpm signal while the vehicle is acting up? Crank position sensors seem to be a common issue for these vehicles as well. An intermittent CKP is a more common issue in general.
I tried to add the scan data as an attachment but it did not work. I am pasting in this response. The last column is the RPM. You can see how it goes from zero to 73,204,253,117 – this indicates rotation – then since it did not start the zeroes come back. This happens a few times – then eventually it starts – see RPM value starting at 673,805,771 etc.
This tells me it is not the crank position sensor. I actually wish it was this since I have 2 of them 🙂
Also I did have a problem with this sensor on an ’03 Sonata that I used to own. In that case there were driveability problems – car would stumble and almost stall then recover. In this case there are no driveability issues at all. Car runs great.BlueDriver Data Log
“Dec 08, 2015 6:39 PM”
“Time(s)”,”Fuel System Status()”,”Engine Coolant Temperature(°C)”,”Engine Coolant Temperature(°F)”,”Short Term Fuel Trim Bank 1(%)”,”Long Term Fuel Trim Bank 1(%)”,”Short Term Fuel Trim Bank 2(%)”,”Long Term Fuel Trim Bank 2(%)”,”Engine RPM(rpm)”
0.0,0,87,189,0.0,0.8,0.0,3.1,0
0.7,0,87,189,0.0,0.8,0.0,3.1,0
1.4,0,87,189,0.0,0.8,0.0,3.1,0
2.1,0,87,189,0.0,0.8,0.0,3.1,0
2.8,0,87,189,0.0,0.8,0.0,3.1,0
3.5,0,87,189,0.0,0.8,0.0,3.1,0
4.2,0,87,189,0.0,0.8,0.0,3.1,0
4.9,0,87,189,0.0,0.8,0.0,3.1,0
5.6,0,87,189,0.0,0.8,0.0,3.1,0
6.3,0,87,189,0.0,0.8,0.0,3.1,73
7.0,0,87,189,0.0,0.8,0.0,3.1,204
7.7,0,87,189,0.0,0.8,0.0,3.1,253
8.4,0,87,189,0.0,0.8,0.0,3.1,117
9.1,0,87,189,0.0,0.8,0.0,3.1,0
9.8,0,87,189,0.0,0.8,0.0,3.1,0
10.5,0,87,189,0.0,0.8,0.0,3.1,0
11.2,0,87,189,0.0,0.8,0.0,3.1,0
11.9,0,87,189,0.0,0.8,0.0,3.1,0
12.6,0,87,189,0.0,0.8,0.0,3.1,0
13.3,0,87,189,0.0,0.8,0.0,3.1,0
14.0,0,87,189,0.0,0.8,0.0,3.1,49
14.7,0,87,189,0.0,0.8,0.0,3.1,136
15.4,0,87,189,0.0,0.8,0.0,3.1,211
16.1,0,87,189,0.0,0.8,0.0,3.1,206
16.8,0,87,189,0.0,0.8,0.0,3.1,201
17.5,0,87,189,0.0,0.8,0.0,3.1,198
18.2,0,87,189,0.0,0.8,0.0,3.1,196
18.9,0,87,189,0.0,0.8,0.0,3.1,195
19.6,0,87,189,0.0,0.8,0.0,3.1,195
20.3,0,87,189,0.0,0.8,0.0,3.1,184
21.0,0,87,189,0.0,0.8,0.0,3.1,98
21.7,0,87,189,0.0,0.8,0.0,3.1,12
22.4,0,87,189,0.0,0.8,0.0,3.1,0
23.1,0,87,189,0.0,0.8,0.0,3.1,0
23.8,0,87,189,0.0,0.8,0.0,3.1,0
24.5,0,87,189,0.0,0.8,0.0,3.1,0
25.2,0,87,189,0.0,0.8,0.0,3.1,0
25.9,0,87,188,0.0,0.8,0.0,3.1,0
26.6,0,86,187,0.0,0.8,0.0,3.1,0
27.3,0,86,187,0.0,0.8,0.0,3.1,0
28.0,0,86,187,0.0,0.8,0.0,3.1,0
28.7,0,86,187,0.0,0.8,0.0,3.1,0
29.4,0,86,187,0.0,0.8,0.0,3.1,0
30.1,0,86,187,0.0,0.8,0.0,3.1,41
30.8,0,86,187,0.0,0.8,0.0,3.1,128
31.5,0,86,187,0.0,0.8,0.0,3.1,193
32.2,0,86,187,0.0,0.8,0.0,3.1,195
32.9,0,86,187,0.0,0.8,0.0,3.1,197
33.6,0,86,187,0.0,0.8,0.0,3.1,198
34.3,0,86,187,0.0,0.8,0.0,3.1,200
35.0,0,86,187,0.0,0.8,0.0,3.1,142
35.7,0,86,187,0.0,0.8,0.0,3.1,61
36.4,0,86,187,0.0,0.8,0.0,3.1,0
37.1,0,86,187,0.0,0.8,0.0,3.1,0
37.8,0,86,187,0.0,0.8,0.0,3.1,0
38.5,0,86,187,0.0,0.8,0.0,3.1,0
39.2,0,86,187,0.0,0.8,0.0,3.1,0
39.9,0,86,187,0.0,0.8,0.0,3.1,0
40.6,0,86,187,0.0,0.8,0.0,3.1,0
41.3,0,86,187,0.0,0.8,0.0,3.1,0
42.0,0,86,187,0.0,0.8,0.0,3.1,0
42.7,0,86,187,0.0,0.8,0.0,3.1,0
43.4,0,86,187,0.0,0.8,0.0,3.1,0
44.1,0,86,187,0.0,0.8,0.0,3.1,0
44.8,0,86,187,0.0,0.8,0.0,3.1,0
45.5,0,86,187,0.0,0.8,0.0,3.1,0
46.2,0,86,187,0.0,0.8,0.0,3.1,0
46.9,0,86,187,0.0,0.8,0.0,3.1,0
47.6,0,86,187,0.0,0.8,0.0,3.1,0
48.3,0,86,187,0.0,0.8,0.0,3.1,0
49.0,0,86,187,0.0,0.8,0.0,3.1,0
49.7,0,86,187,0.0,0.8,0.0,3.1,0
50.4,0,86,187,0.0,0.8,0.0,3.1,0
51.1,0,86,187,0.0,0.8,0.0,3.1,0
51.8,0,86,187,0.0,0.8,0.0,3.1,0
52.5,0,86,187,0.0,0.8,0.0,3.1,0
53.2,0,86,187,0.0,0.8,0.0,3.1,0
53.9,0,86,187,0.0,0.8,0.0,3.1,0
54.6,0,86,187,0.0,0.8,0.0,3.1,308
55.3,0,86,187,0.0,0.8,0.0,3.1,673
56.0,0,86,187,0.0,0.8,0.0,3.1,805
56.7,0,86,186,0.0,0.8,0.0,3.1,771
57.4,0,85,185,0.0,0.8,0.0,3.1,745
58.1,0,85,185,0.0,0.8,0.0,3.1,731
58.8,0,85,185,0.0,0.8,0.0,3.1,720
59.5,0,85,184,0.0,0.8,0.0,3.1,726
60.2,0,84,184,0.0,0.8,0.0,3.1,731
60.9,0,84,183,0.0,0.8,0.0,3.1,733
61.6,0,84,183,0.0,0.8,0.0,3.1,734
62.3,0,84,183,0.0,0.8,0.0,3.1,737
63.0,0,83,182,0.0,0.8,0.0,3.1,739
63.7,0,82,180,0.0,0.8,0.0,3.1,746
64.4,0,82,179,0.0,0.8,0.0,3.1,761
65.1,0,81,178,0.0,0.8,0.0,3.1,775An update on my issue. I did some research on flooding fuel injected engines and clear flood mode. The crank no start condition reared its ugly head twice over the last couple of days with my wife driving the car. I had explained to her to floor the gas pedal then crank the engine to activate clear flood mode. Both times she told me this got the engine started. So it seems likely that the engine flooding is causing the issue and would explain why it is intermittent and why the idle is rough for the first few seconds after it starts when this issue happens. I have already replaced the fuel pressure regulator so I am thinking I have an injector that is leaking. I am going to run a few tankfuls of gas with techron concentrate added at fill-up time. I don’t know if this is a waste of time or if it has any chance of fixing a leaking fuel injector. Any thoughts would be most welcome.
If it is indeed a leaking fuel injector running the cleaner through them wont hurt anything. I will tell you that Modern cars rarely flood. I have seen a ford with a stuck on fuel injector spraying fuel all the time and it still started. It ran rough but it started.
In case anyone is still following this… ran 2 cans of techron through the car. It seemed to help (especially at first) but the issue still happens occasionally. Using the clear flood mode starting technique continues to work. Meanwhile I found a set of 6 OEM fuel injectors from Hyundai sold by Fourgreen auto parts for $153 delivered to my door. What was really amazing is the FedEx delivered them from Seoul Korea to my front door in Florida in 2 days!! This past weekend I replaced all the injectors. Time will tell but I am hopeful that this is the fix. I will report back after some time has passed.
It has been a little over a month now since replacing the fuel injectors. So far so good. Since the replacement the car has consistently started on the initial crank with a couple of seconds regardless of how long the car has sat. I am cautiously optimistic but still not yet completely convinced the issue is resolved.
Great news my 03 sonata had the stalling while driving issue dam those cars for the crappie cps sensor.
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