QuestionQUESTION: I've replaced the plugs, wires, and ignition coil. The starter rotates, but the engine never catches, and it doesn't sound like I'm getting any spark in the cylinders. The fuses are all fine, nothing blown. I'm wondering where to go from here? Is my ECU fried?
ANSWER: It's doubtful there's a problem with your ECU. That's a very rare issue. To help send you in the correct direction, I'll need to get some more information from you:
1. I'm presuming that the starter cranks the engine but the engine doesn't start. If the starter runs but doesn't crank the engine, please indicate this.
2. Does the engine crank fast, slow, or normally?
3. Did you check to see whether you were getting spark? If so, how?
4. Did you check to see if you were getting fuel? If so, how?
5. Do you have access to a code reader/did you check for trouble codes?
6. Was the check engine lamp coming on prior to this issue?
7. How many miles are on your 2000 Elantra?
---------- FOLLOW-UP ----------
QUESTION: Well, either it's "fixed" or the problem's a ghost. I tried a jump yesterday, which didn't work, waited an hour, then pressed all the electrical connections in tight (fuses, cam and crank sensors, everything) and finally got it started. Ran really rough for a few minutes, but then it evened out. I just tried it an hour ago after sitting all night and it started immediately. For clarity of the question:
1. Yes, the starter was cranking, but I wasn't getting ignition.
2. Until the battery wore down, it was cranking at normal speed.
3. A neighbor checked to see If I was getting spark from the coil, and I wasn't getting any spark down the wires.
4. Same neighbor checked the fuel line running into the injectors (i think), and stated I had good fuel system operation.
5. No code reader unfortunately.
6. There was no check engine light. It went from working to dead overnight. Even when it wasn't starting I didn't give me an error.
7. My Elantra has 131,000 miles on it.
After sitting all night, it fired up immediately, idles normally, no ticks or knocks. No clue why it gave me so much grief after the coil was replaced. I'm going to keep a close eye on it over the next few days, see if it crops up again. If it does return, what do you think my next stop would be on the troubleshoot/replace list? Since the ECU isn't a likely culprit (happy news there!)? Thanks so much for your help!
AnswerMost situations on newer vehicles where there's no spark are the result of a defective crankshaft position sensor. The ECU needs the signal from this sensor to determine when to fire the spark plugs and injectors. In some circumstances, symptoms will be experienced prior to the check engine lamp coming on, but after a diagnostic trouble code has been set. Since the car is working normally for the moment, perhaps stop by an AutoZone and have them interrogate the ECU for trouble codes. If you have a code indicating a problem with the crankshaft position sensor (typically P0335), I'd recommend replacing it now; it'll surely act up again if it has a problem and is ignored.
