QuestionHi
I have a 2002 Hyundia Elantra while driving at any speed or weather conditions, the car seems to lose power jerks,and the check engine light blinks on for a split second. This situation happens many times in a row, the car is pulled over and the key turned off. It will re-start immediately. The MAP sensor, the throttle position sensor, and the idle speed control valve have all been replaced. Also, new wires and boesch platninum2 plugs. This situation can happen when the engine has just been started or after(during a 150 mile trip any ideas? I have an Apt. with a Hyundia dealer in 3 days I would like to help him have a starting point-this is the service manager since this is the second time I have taken the car in for this problem. By the way there are no codes present.
AnswerI'll start by saying that no dealer with competent personnel will be interested in what I tell you. They'll be perfectly capable of performing their own diagnoses and contacting Hyundai technical assistance for access to a national database of problems with similar symptoms on similar cars.
The fact that the check engine lamp comes on momentarily but there are no trouble codes suggests that the engine control module (ECM) is turning off. The question is why this is occurring. There are several potential problems that would cause this:
-- Positive battery cable shorting to ground
-- Defective engine control relay
-- Defective ignition switch
-- Poor contact in ECM ground
-- Defective ECM
-- Any wiring issue preventing power from reaching ECM.
If I had to make a guess and the battery cables checked out okay, I'd start with replacing the ECM relay since it's probably the most likely culprit along with being inexpensive and simple to replace. If the problem occurs again after replacement, you haven't lost very much.
If the dealer (or other shop) cannot perform testing while the condition is occurring, there's no way of determining for certain what the problem is.
