Problem with unstable RPM while moving

Thanks for this post I had this problem and the service fixed it. I love this site.

My car's RPM has started fluctuating ever since I got the throttle body serviced. The rpm rose beyond 1000, after the service.I noticed it and the next day I asked my mechanic to fix it, because earlier on it was perfectly stable and the car was giving good mileage too. He very reluctantly slowed it down by turning a screw with an allen key on the throttle body, where the throttle plate rests. With that, for the time being the RPM came down to normal but started fluctuating when the air-conditioner was turned on. When the radiator fan starts automatically, the RPM drops slightly as if the engine was about to stall, but then gains and comes back to normal. This is felt more when you are driving in town and in traffic where u have to stop at traffic lights etc. Hardly felt on a long drive or highway. A Honda pitstop mechanic, whom I went to lately, reset the entire thing, using a computer but my car is still not the same. Pls advise!

Thank u very much Roy.I will start looking for it cos I doubt if the spare part dealers keep brand new throttle bodies cos anyone hardly changes them. However I will check the market. Thanks again.

My friend and I just replaced the cylinder head in my 1987 honda civic and took it out for a short test drive (5 mi). On our return trip, the car suddenly was hard to control, but we made it back safe (whew). When I parked the rpm's were at 4000 (!), Same when in neutral. Gas pedal seems normal. We think we probably knocked something out of place in the carburetor when installing the head - any thoughts?

It idles at 4000 rpm -so I can't hear anything (!) But the engine. Had no idea a vacuum leak could do this, hmmm. I guess we'll have to check all the carburetor lines.

Hi,

My car is 2004 Automatic, Made in Thailand imported in UAE. Recently my car started giving jerks when running at slow speed (between 20KM-60KM). I did not notice the jerks at higher speed. One local mechanic asked me to put Injector cleaning oil in in the fuel tank and after that it worked fine until the next oil change. It started giving the same jerks when I filled the patrol tank. Again I put the same oil in the Patrol tank but this time the jerks not vanished.

I have changed the engine spark plugs and now my mechanic is suggesting the spark plugs coils to be changed for testing.

I'm feeling the jerks and whenever the car stops at red signal I have to either switch off the Air Conditioner or give much acceleration. The RPM needle is not stable also it goes to 2000 RPM and then with jerk it comes to 1500 and then suddenly it change. It is not stable.

The new coils costs too much and he is not sure also that installing new coils will fix the problem or not.

The honda service station is quoting 140$ for diagnosing the problem. Please help me.

With Regards
Yatin

Hello KHLow2008,

The engine check light (Malfunction) is not turned on so I did not get it checked from computer. I drove to high way and I felt the same jerks at the speed of 75 miles also. One of the local mechanic suggested me to change the spark plug coils. Kindly suggest.

Regards
Yatin

Hi Yatin,

You got any solution for this? I am facing the same problem with my honda city 2008 model.

Naveed

When I'm driving my car, often it operates smoothly and no issues, but on occasions, I do experience a problem, that the RPM increases, even when I'm braking or change gears, the RPM increases, and the engine revs up. The acceleration also increases, but it's under control, not very dangerous. However it's irritating and it's a problem I can't quite figure out as to why this is happening.

When I start engine rpm comes down on o and car switch off.

I had an engine overhaul. Since then, the RPM does not stay stable and keeps fluctuating up and down when in drive. The acceleration has also significantly decreased and seems that the car is choking. Had a computerized check up and it suggested high air input. Have tried replacing sensors but that has not helped either. Sometimes the engine starts missing all of a sudden so even tried replacing the distributor but without much luck. Had the plugs replaced with new ones too. Seriously running out of options guys. Please help !