Car jerking at constant rpm while driving? - 1

I have honda civic 1999 exi. During the drive the car shuffles and takes small jerks normally between 2 to 3k rpm speed, i got scanned my car nothing found, get new fuel filter installed and try Hi octane fuel but problem still persists. When i accelerate the car it stops jerking. I also cleaned fuel injectors last month its happening in all gears and car tsansmission is manual please note its a dual fuel driven petrol and and cng as well. When i shift it on cng (compressed natural gas) it runs normally and well without jerky drive. Seems problem with petrol only
any body help?

Them cars have or can get a dirty intake system. Clean the maf sensor and check the fuel injectors with a multi meter. While your at it see how many volts your battery holds disconnected. Have car running and test the altinator! Get a voltage reading from the grounds. If all checks out perfectly fine! Buy the oem spark plugs and see if that helps.

So its something with the gas end of the system. I would first try cleaning the mass air flow sensor for a cheap idea then move to plugs and coil packs or whatever honda uses. You have tried the fuel end of the spectrum and really the only things left is air and spark. With it being that specific between 2-3K i'm guessing spark will solve it. So time for a tune up.

That is a classic symptom of a worn TPS. The Throttle Position Sensor is on the throttle body and easy to change. If it were mine I'd change it.

Hi so here we have one very worn out car at now 16 years old what do you expect new car performance to to get real here sunshine old and worn it is a miracle it still is running.

Look for a vacuum leak. On an efi engine, the o2 sensor will show a condition where not enough fuel was used and more will be added increasing the rpm. Then it sees and issue with that and drops fuel dropping the rpm. Ill bet that it runs a bit hotter also.

Throttle Position sensor(on the throttle body) or Speed Sensor(on the transmission). It could be either, or it could be both. Both are simple to replace (unscrew old one, screw in new one) and both are going to go in another 3 or 4 years or so anyway (car is 16 yrs old). Speed sensor will affect gas but not CNG because CNG metering mechanism (pressure regulator valve) is much smoother than liquid fuel metering mechanism (FI control system).

Ex/ Google search "1999 civic exi throttle position sensor" for pics and related forum threads.

As another posting suggested, it may also be a vacuum leak somewhere on the intake. It could also be the Idle Air Control Valve is sticking due to oil gum built up in the intake.

If it was my car, I would clean out all the intake parts especially the IACV and MAF sensor, install a new air filter, and then carefully check the intake system for any vacuum leaks. If the problem were still there, I would replace the TPSensor and the SpdSensor. If the problem still persisted I would try swapping out sensors before committing to buy one, starting with the MAF sensor. If I still had not found it, I would cave in and take it to a full-service shop for some diagnostics and professional tests. Such is life.