Yesterday as I crawled my way through heavy traffic on my drive home from work, my car started lurching unexpectedly. When I let up on the gas, the lurching subsided. I was able to recreate the behavior multiple times on my drive home, as well as while parked in my driveway. As the RPM exceeded 2500 the engine would lose oomph/power and the RPM would start stuttering/oscillating between ~2500 and ~2800 RPM. The behavior was identical regardless of which gear I was in (D1, D2, D3, D, or N), regardless of my speed, and regardless of how aggressively I was pressing the accelerator pedal. Every time the RPM hit 2500, the engine freaked out.
This morning, it did NOT happen when I tested it briefly. I was able to rev up to 3500-4000 RPM without any issues. I did read a case online in which someone experienced a similar issue that only manifested after the engine had been running a while.
My car has ~173k miles on it, and this is its first engine issue. Does anyone know what might be causing this? Thank you.
Get the codes read , an ignition miss can cause this . It appears that your service engine light is on . I had an engine doing that only mine was at 2200 rpm’s . Turned out to be a loose connection where the wires plugged onto # 6 coil .
Make sure the engine oil and coolant levels are ok. There’s no signs of overheating, right?
hmm … well, first off, the advice above is excellent, have all the diagnostic codes read out from the engine computer memory. The answer may well be obvious from that list.
If not, it’s possible you are experiencing a transmission problem rather than an engine problem. Might be just a torque converter lock up problem. That’s usually reported as a shudder though. But what you call a stutter or oscillation someone else may call a shudder.
Beyond those ideas, on my own vehicles I’ve experienced lurching/surging/waning engine oscillations a few times, those were caused by
grit contaminated carburetors,
grit contaminated fuel injection metering system,
large vacuum leak.
clogged engine air filter
Faulty fuel pumps are reported to cause this symptom too.
Instead of a cable running from the accelerator pedal to the throttle body, your vehicle has an accelerator pedal position sensor that sends a signal to the computer. The computer then takes that signal and operates the electronic throttle body.
If the signal from the accelerator pedal position sensor is erratic, the computer doesn’t know where exactly to position the electronic throttle body plate. So the RPM’s will fluctuate in that bad spot of the accelerator pedal position sensor.
Also…and I know this sounds funny… check your coolant level… You may be describing “Idle Hunt” condition caused by low coolant level and the engine not knowing how hot or cold it is…and thus not knowing how to control the IAC valve…if so equipped. This is a common issue on earlier models…newer ones may not be exactly the same but…its good advice nonetheless.
All the guys gave you good things to check…of course read the codes…if you have a CEL…it is trying to tell you what needs attention
Because it did not malfunction when you started it this morning, a bad upstream oxygen sensor is also a possibility. When the engine is cold, the ECU ignores the upstream sensor to allow the engine to run rich.
As Honda pointed out, a bad temp sensor would cause a similar symptom by not letting the ECU know the engine has reached operating temperature and it could be still running rich when it shouldn’t be.
As everyone said, start by getting the codes checked. They’re the place to start. We’re all just suggesting where the codes MIGHT lead you.
If there is an AutoZone, O’Reillys, Advance Auto, or other chain type auto parts house you might drop by and have them pull any codes for you. They will do this for you free of charge.
Some states such as California and Hawaii will not allow this.
The parts store will give you the code; or codes. Their job is to provide codes only; they do NOT diagnose the problem. Or at least they should not try to.
If you get the numbers you might post them back here for further discussion.