Bad throttle responce

[rn240sx]

Here is the deal:

While im driving at normal speeds, i touch the gas pedal to accelerate and the motor does not repond... I BARELY tap it like 1/4 inch and there is no repsonce from the motor until i push in the pedal in farther, then it goes, and when it does go, it has a slight hesitation, but then releases and goes full like normal..

This happens at all speeds and all gears....

For some reason its like the motor wont respond unless i hit the pedal farther than barely...

One other strange thing is while im watching the AFC, i noticed that my Throttle readout seems to be a bit higher than normal (while driving only)

I can sit there and start to press on the gas pedal and slowly push down as if i was accelerating and i can see the afc reading the throttle %... and for some reason when it reads 50% throttle i noticed that the pedal was NO WHERE NEAR 50%.....

But then when i let off completly, it goes back to zero like it should..

I changed out the MAF and i still have this problem which only leads me to the TPS next... cause i dont know what else controls throttle responce..

[fiznat]

Look at simple stuff first. Check the actual cable throttle and make sure that it is tight. Make sure that 0% throttle (0 tension on the cable) keeps the throttle plate closed, and then any tension thereafter starts to open the plate.

If that looks okay, get out a multimeter and check the TPS sensor (attached to the throttle plate itself on the side of the throttlebody). If I remember correctly (I will check), a closed throttle will read around 0 volts (and stay fairly steady), and then opening the throttle slowly will ramp the volts up smoothly to 5 volts.

Make sure both of those parts are in spec and then move on to more complicated things.

[rn240sx]

Ok i checked the tps voltage and i got .51 volts while it was just sitting there with the motor off and ignition on...Then i slowly raised it watching the voltage rise and it got to 4.15 volts where it stopped...

[virus77]

4.15 or 4.17 is where mine was always at on WOT. closed throttle is somewhere near the number you mentioned aswell I cant remember exactly.

[S14tat]

besides checking throttle voltage like what everyone else says with the SAFC II you can also check your timing. maybe its waaay off and too retarded. sometimes if you don't tighten the distributor enough it will move little by little over time and hte timing might jump.

[Structure240sx]

the safc doesnt tell you timing

do you have your wideband in while driving? definily could help.

factory tps voltageis .49 at 0% throttle, mine is around .50-.51 i never bothered to adjust it

[rn240sx]

do you have your wideband in while driving? definily could help.

Yes i do, what should i be looking for..??

[Structure240sx]

lean conditions 17+ afr's is usually when you can feel hesitation, also very retarded timing but you need a scan tool for that. i've noticed similar times on my car just like you mentioned. not too often but occasionally. i usually just give it some gas and dont worry about it. i know you are more meticulous than me and want a stock running car. so if you figure out what it is let me know

[klattr1]

check your 02 voltage when its doing that hesitation or at the bad throttle response spot.

[S14tat]

the safc doesnt tell you timing

do you have your wideband in while driving? definily could help.

factory tps voltageis .49 at 0% throttle, mine is around .50-.51 i never bothered to adjust it

oops i forgot to put in the comma. i mean you can check throttle voltage with SAFC, and you can also check your timing. ( not with SAFC ) sorry if that came off confusing.

[nissanfanatic]

.4-.5 volts is factory spec.

I have the same problem as you. I also get hesitation in third gear on my first acceleration of the day. If I'm in closed loop on the first acceleration, I can see that it leans out to like 17, then back to normal really quick. Feels like dead spots. I think I'm gonna check out my O2 sensor and then go from there.

Edited voltage after confirming with FSM.
Modified by nissanfanatic at 8:28 PM 5/5/2005

[fiznat]

^^ nissanfanatic, that sounds like the ignition missing to me. You will see a quick lean condition and then it will return back to normal... Check over your ignition system (especially plugs)... if everything is up to spec, try regapping down to high .020s or so.

[NateDogg]

I bet this is all vacuum leaks.

[Structure240sx]

i bet its not

[nissanfanatic]

Already did. Plugs are gapped at .028" and torqued to 15ft-lbs. Wires are brand new Magnecors. Coil is a brand new MSD Blaster SS. Running a MSD BTM. Car doesn't miss whatsoever in boost. I'm thinking that the plugs are gapped down too much. But IDK. IT does exactly what you said though. I'll def go through and check everything again though. Thanks.

[Structure240sx]

not that it will make a difference but more for myself, arent the plugs torqued to 22ftlbs? or is it 15-22flbs? i tend to torque to the recommended limit

[fiznat]

who the hell actually uses a torque wrench on spark plugs??

[nissanfanatic]

I do. Torque is actually very important when it comes to spark plug installation. Torquing plugs info After having the FSM, I just torque everything so there are no reasons why anything should fail.

Structure it is 18-21ft-lbs. I torqued them to 20ft-lbs. I tend to torque right in the middle of the numbers so I have room either way if my wrench is off or whatever.

I also use anti-seize lube.