Q: What would make my car stall with picking up speed?

asked by on May 23, 2017

What else could make my car struggle to gain speed & idle loudly? My car started struggling to gain speed & felt as thought it were back firing when trying to gain speed. I've changed spark plugs & engine core packs, & Now it feels worse & will not idle lower than 1½ on the RPM gauge. Engine light is on but its been on since the problem started. Auto zone test said All 4 cores read bad, So that's why I changed them, followed by spark plugs when cores alone didn't fix the problem. Now it seems to be making all sorts of noises squeeking & other things too.

My car has 149500 miles.
My car has an automatic transmission.

If the fault codes are reading all 4 coils are bad and the codes remain even after replacing the coils, then the problem is elsewhere. It is very rare to have 4 cols fail at once. There can be an issue with the engine wiring harness. A break or short circuit anywhere in the harness can cause numerous fault codes and running issues. Also, the engine control unit can be faulty. If the ecm is not properly signaling the coils to fire, this can cause misfires and misfire codes. Even the crankshaft position sensor can be a possible cause. If it is not signaling the ecu properly, the coils may misfire. Sometimes fault codes can be the symptom and not the exact cause of the problem. It might be best to have a certified technician properly diagnose why the check engine light is on and determine why the fault codes are present.

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