rotascircuit

Hey I got a 95 civic with a 95 gsr engine. when I cruiz on low rpms and I all of a sudden give gass, the car sarts jerking and I mean you can feel it jerk. But when it gets into higher rpm it is fine so what can it be? I called the performance dude and he said it sounds like tps. ???????????????????????? anybody in sacramento area know about swaps and b series that can test drive it??

97Ej6mike

a FITv or vaccum leak will cause odd lower-RPM jerks (usually under 3k rpms). Allot of the time it turns out to be a FITv that got stuck in the open position. Also check for any other vaccum leaks around your manifold.

rotascircuit

should I take some soap and water and spray it on? btw what is FITv

97Ej6mike

the FITv is the valve (fast idle thermo valve) under the throttle body that is run by coolant temperature. When you have a cold startup, this valve is in an open position, allowing a controlled vaccum leak to raise the idle when the throttle butterfly is still closed. In some cases, as cars age, this valve can wear out and not work as well as it used to. I had a problem before where mine was getting stuck in a slightly open position. What this caused was an idle at 1500, and a 2-step like shudder from reving it anywhere under 3k rpms.

I think this is because that more air is making its way into the cylinders as compared to what the TPS signal is reading ( to compute fuel input), causing it to jump erraticly up and down about 75-100 rpm's becuase of the imbalance. Thats just my personal scientific theory on how that occurs. I dealt with the problem for quite awhile, and after trying every possible thing, it turned out to be a FTIv stuck in the open position.

Budget Racer

I have had this happen from old spark plugs, and the TPS could cause it too.
I don't no much about the fitv. Try looking at your spark plugs, and possibly your cap and rotor.

hhn_jff

I have a 95 4 door lx that is doing the same thing. When I first start it up it runs just fine. As soon as it warms up it wont rev worth anything, until high rpms. I checked the TPS sensor with a volt meter and it looks to be good but if i unplug the wires to it it runs the same.

rotascircuit

Hey are you in sacramento to test drive my car?