99 Sonata cuts off

My sons 99 Sonata I4 (that I gave him 5 years ago, now with over 90k miles) stopped on him yesterday leaving work. He had gone less than a mile when he
stopped at a stop sign, when he pulled away it went about 20 feet and died. It would not start for 5-10 minutes and then suddenly started. He drove off as if nothing happened. He said that it felt and sounded perfectly until the problem and also afterwards. I had him to bring it by my house on the way home and I did a OBD scan to see if it had stored a DTC, it hadn't and all monitors showed ready. I opened the hood and it was purring normally and very still while idling. He was ready to drop it off at a shop but I explained to him that he would be wasting his time (all closed for the day anyway) since there was nothing apparent for them to fix or anywhere to start looking. It has been well maintained including the timing belt replaced at 60k miles. So far its been ok but I am pretty sure it is just a matter of time before it will occur again. I am going to take a look at it this weekend but as of right now, I have no idea where to start looking. Hopefully by then someone on this list will give me some helpful suggesting (HyundaiTech, are you there?) Thanks
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My initial guess would be the crank sensor, but that normally leaves a code. Does your code reader check for pending faults as well as faults which turn on the check engine lamp?
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Thanks Hyundai tech for your quick reply. Yes my code reader manual says it reads pending codes but I've never actually seen one (hopefully because I've never had one). I wont get a chance to look at it tho because it died on him today going to work ( both ways yesterday without a problem). He could not reach me so he had it towed to a shop. They called later in the day and said that the valve cover was leaking oil into the spark plugs and had shorted out the plugs and the coil packs. They said it would be $750 to repair. I had him call them back and ask them 1) how did 4 plugs and two coil packs short out at the same time. 2) Did they see any spark at all . 3)was there any DTC and 4)What was the odds that that was going to fix the problem? He said that they said there was no DTCs and there was a very weak spark. They got huffy on the other questions and said that was all they could find and it would fix the problem. I told him that I didn't think they had a clue as to what was wrong with it and was just throwing parts at it but at this point he didn't have a lot of options but to go along with it. What are you thoughts on this diagnosis? I sure hope for his sake that I am wrong and that this fixes the problem , but I have serious doubts. I will post the results when I hear more.

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Seriously doubt it'll fix the car. Diagnosis is BS or just plain ignorance. The oil will not short the spark plugs. I don't even recommend doing the repairs if the car seems to otherwise be running normally.
Think about it. Two coils shorting out at the exact same time in three separate instances. That itself is not believable. Furthermore, if it were just one coil, it'd still run (although not very well) on just two cylinders.
Of course, I'm not confident my original post is the correct diagnosis, either. (I will say, however, that it's more likely than two coils, four plugs, and a valve cover gasket.) This car also has a primary coil side ignition monitor that can fail and prevent the coils from firing. If the shop actually found no spark but had injector pulse, the ignition monitor would be the prime suspect.
-- Message posted using http://www.talkaboutautos.com/group/alt.autos.hyundai / More information at http://www.talkaboutautos.com/faq.html
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He got the car back the next day and says it running OK now. That was a relief because we both were expecting them to come up with more $$ needed to get it working. Now it leaves me wondering if they found out early on that it was something relatively cheap and padded the bill with expensive parts/work or discovered afterwards that the initial parts/work didn't fix it but decided to eat the additional cost to save face. Or worse yet, since its an intermittent problem (it went two days in between occurring) that its not really fixed at all and will occur again at any time. I guess time will tell. Anyways, thanks again HyundaiTech for you comments. We were both on the same page.

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