s14, engine twitches

[pitesy]

Hi!

Just in advance, I'm not 100% familiar with some technical words, because I'm from Hungary. So sorry about misspellings, and other grammatical errors.

So here it goes:

The car is an s14, engine is stock sr20det. On lower rpm's, especially between 2000-2300 the engine "twitches". Feels like it just won't fire, or cuts, or something like this. When I try to be gentle, it just gets worse. I hope you got my point. :) On higher rpm's I haven't experienced this. I bought the car yesterday, and had to drive it back home 1100 km's.
The car boosts fine, fuel consumption seems okay, and engine power feels okay also. Idle is fine aswell.
The previous owner said there were problems with the coils, he replaced them, and now it seems to be okay. I thought about checking/replacing plugs, checking the wires...

Other:

So please guys, any ideas where to start?

[Kingtal0n]

Hi!

Just in advance, I'm not 100% familiar with some technical words, because I'm from Hungary. So sorry about misspellings, and other grammatical errors.

So here it goes:

The car is an s14, engine is stock sr20det. On lower rpm's, especially between 2000-2300 the engine "twitches". Feels like it just won't fire, or cuts, or something like this. When I try to be gentle, it just gets worse. I hope you got my point. :) On higher rpm's I haven't experienced this. I bought the car yesterday, and had to drive it back home 1100 km's.
The car boosts fine, fuel consumption seems okay, and engine power feels okay also. Idle is fine aswell.
The previous owner said there were problems with the coils, he replaced them, and now it seems to be okay. I thought about checking/replacing plugs, checking the wires...

Other:

So please guys, any ideas where to start?

sounds like either it needs new plugs or it has a lean misfire. The "twitch" is usually a misfire, as I said, usually either because of old plugs (or too large of a gap) or a lean situation. You may have a Bad O2 sensor, causing the ECU to pull some 17% of fuel during cruise. You can verify this by simply unplugging the O2 sensor and seeing if the problem dissapears. you may have a failing injector or a failing fuel pump or a failing fuel regulator also, as these may cause this situation. So would a bad maf, but i would consider the MAF last.

[rcdad123]

also check the tps.

[pitesy]

Thank you guys for the hints! I really appreciate it!
I'm going to check everything today.

[mhubble91]

i agree with rcdad123, check the tps....

the tps is a potentiometer, and for example think of it like this...

when you're wide open throttle the TPS (throttle position sensor - located on the throttle body, opposite of where your accelerator cable is attached) sends a 5 volt reference signal to the ECU. MORE throttle, MORE voltage. With that said, if your car is driven at a certain RPM, or at a certain pedal position for most of it's life the TPS will have a worn out spot on it and can not send a good signal to the ECU, thus droppping voltage. So the ECU thinks it's at a different position -- in return it cuts fuel in it's confusion.

Sorry for any confusion. Really hope this helps.

Good luck.