txiki

Hi:
I didn't use my 97 sentra for a couple of weeks and now when it warms up, the car jerks. Any idea what the problem can be? I have changed already the fuel pump and distributor cap. The car has 110.000 miles. Thanks

jdgrotte

How about checking the rotor, spark plugs, spark plug wires, any and all electrical connections leading to and from your engine and ECU, wiring in the dash, battery connections, TPS readings, MAF readings, knock sensor readings, O2 sensor reading (upstream, not downstream), CTS values both cold and hot, transmission fluid, or if it's a manual, clutch wear, jerks while acclerating, jerks while idling, jerks at a steady speed in town, down the highway, and any number of other things I didn't mention.

In other words...not a whole lot of information to work with here.

txiki

Thank you for the answer, I'm not a mechanic and I do not know how to check most of those items.
It jerks when accelerating then is OK. It is standard.

Faja

Try these in this order Txiki.

Change fuel filter and then check jerkiness

If still there, then replace rotor, sparkplugs

If still jerky, then try ignition wires - good luck

zacward

Check fuel pump too. Although if its the pump and not the wiring, it will prob go out very soon and then you get to push your car

txiki

Faja:I will try in that other and let you know,
also, how can I check the fuel pump?
Thanks Faja and zacward for the help.

Faja

When you turn the key in the ACC position, you should hear a slight humming sound for a couple seconds then it will stop. You said you changed the fuel pump and distributor so I didn't comment on those. If your car is starting with no problems chances are your fuel pump is OK.

txiki

The car starts with not problem.
I will replace the rotor, wires and spark plugs and I will let you know.
Thanks Faja.

zacward

You may have put your distributor in upside down.

mattdc_07

Upside down??

zacward

Backwards? Where it starts on the exhaust stroke, not the intake stroke. In other words, not very descriptive but where you would take it out, try cranking or turning the crank (getting out of TDC) and then put it back in without knowing that youre doing everything wrong.

txiki

It is installed the right way.
I have changed the rotor and after the car gets warm it start to jerk again.
PS:I was wrong I have changed the fuel filter not the pump, sorry.

Faja

It is also possible that one of your 02 sensors might be going bad as these have to warm up first also before functioning properly. It might be advisable to take it to a mechanic and have him test them for you.

txiki

I will do that too. BTW, is there more than one O2 sensor? If so, where are the located? And if it is faulty, would the engine light come on?Thank you Faja.

Faja

Yes, technically there are more but the one that is in question here is the one near or on the exhaust manifold (I don't know the specifics of your car so I'm generalizing). It might not send a CEL if it's just faulty but could send wrong information to the ECU which could cause the wrong mixture of A/F that might cause the jerkiness. Remember that these are just educated guesses as I am not an expert nor a mechanic!!!