OVRBST

First off, the car belongs to JKISINEFFECT. I am doing some work to it for him, and have run into this little issue. Also, it's a 94 base model with 112K original miles.

Ok, at 1-3% throttle the car seems to show no throttle response whatsoever, then all of a sudden it comes alive, and gives you this on/off feeling (Jerky to drive at low speeds/cruise). I know in the past with other cars it's generally a TPS problem, but before getting into it to deep, I figured I'd ask and see if anyone else has had this issue.

Also, the car is bone stock except for a DP and exhaust. All vacuum lines seem ok, and the car runs/idles/drives fenominal. All filters/fluids/belts/hoses/plugs/wires have been changed yesterday.

XSTransAm

check the line to make sure its tensioned correctly... other than that? i dono

jkisineffect

thanks ....... my freind "alex" AKA OVRBST
is working on my car any info on this problem
would be really helpfull

JOHNNY

matty

can any one tell me more about what a tps is and how i replace it?

tcb100

Throttle Position Sensor. It tells the ECU how far into it your foot is.

Why do you think you ned to replace it?

matty

hey thks.
i think its soemthing else then. My car will studder and jerk when on very very partial throttle and when going off -on throttle. It will also back fire when going on- off throttle on occassion. i think its cause i am too rich? any clue how much fuel i should take out on the power fc? also which method is best 1) in pim volt or 2) pim volt V?

even if i am in neutral and rev to 3k rpms and HOLD it there the car will pop and isnt smooth. Everywhere else in the maps the car runs flawless.

Trexthe3rd

What rpm is the car idling at? Is the throttle cable loose? How old is the clutch?

matty

actually i just ressurrected this thread...lol. not sur eif guy is still around.

tcb100

Matty do a search for a tps thread by Damian that discusses how to adjust the TPS. In fact your symptoms could be a misadjusted TPS.

You should at least check it out.

matty

i will. but problem showed upn after a tune and installation of twin power. seems ironic that my tps would get screwed up when we were tuning the car. makes me think it is more of a tuning issue.

matty

io also want to add that there are no other problems, ie no idle problems or anything else. The problem exists only when i hold revs contant like when cruising or when i go on off throttle

matty

bump

alberto_mg

matty

do the following to check your TPS:
- jot down the TPS values in this thread: https://www.rx7club.com/showthread.p...&highlight=tps
- bring the car up to operating temp (I'm sure you know a fun way to do that)
- turn it off
- grab the commander and go to the etc on the menu
- check out the values for the VTA1 and VTA2 comparing to the ones you jotted down from the above thread or from the FSM
- first compare the values with just the key on i.e. not pressing on accelerator pedal. i think the VTA1 is the narrow setting referenced in FSM and thread above.
- now press the accelerator pedal down all the way (pretend you are doing a 1/4 mile run ) and compare the values for VTA1 and VTA2 with the full-open values.

that should tell you whether or not your TPS is off. refer to the link above for the how-to adjust.

worse case scenario also take a look at your plugs.

rynberg

Sounds more like a closed-loop control problem to me....is your PFC setup to use O2 feedback? If so, how old is your O2 sensor? If not, perhaps you need a little tuning work in the vacuum ranges.

matty

the problem arose right after a tune and right after installation of twin power. The car was tuned with 02 feedback off. after discussing issue with the tuner he recommended turning it back on. However the issue persists. I tried removing fuel (as much as 5%) via pim volt and pim volt V however it didnt fix it. To me it seems like a fuel related problem rather than spark as the car will backfire when i go ON throttle sometimes. If it was spark wouldnt the car not run correctly when on full throttle and ripping thru gears? i mean my car runs like a friggen dream when wot. My car traps very high for a stock twin stock motor car.

The O2 sensor is as old as the car 11 yrs.

ty for the look on the tps. i am goign to check that,. couldnt hurt. hwoever i think its soemthuing else as the problem started aright after a tune and install of twin power.

DaveW

There's your answer (maybe).

I'd bet it needs a new O2 sensor - they usually only are good for 60,000 miles or so...

matty

really? how much are they? is it posible it could have failed on day of dyno tuning?

car has 48k miles. is there a way to test the 02 sensor?

tks for reply.

DaveW

My FD has 50K miles and the O2 sensor is still OK (I think). However, running leaded gas, etc., can quickly coat (foul) the sensor, making it unresponsive. Running super-rich can also foul the sensor, but it will usually recover from this as the carbon burns off during spirited driving.

IIRC, there are a variety of O2 sensors available for around $50 or less. If the search function is working, there have been several recent threads about what's available, and which type (heated or not) is suitable.

Mura

So by correcting this, would it correct the response of you putting your foot to the floor, or what? And if it doesn't get corrected, how much of an effect would it have on the car?