Flat Spot

[TODA AU]

An incorrectly set one will bring on over run fuel cut prematurely.
This could be from something as simple as being knocked by a heavy object.

[tinkerbell]

yes, that is true...

for those wondering - "over run fuel cut" is where the ECU senses that the throttle is closed above around 1100rpm and therefore the PGM-FI system shuts off the fuel injectors to reduce fuel consumption...

i.e. TODA AU is saying that the TPS sensor might, at light throttle, think the TPS is closed, and therefore shutting off the fuel injectors to save fuel.

to test the TPS, get a multimeter, set it to 0-5v or similar, and place a fine metal pin (i use a sewing pin) into the centre wire on the TPS (whilst still plugged into the TPS) and attach the +ve (red) cable of the multimeter to the pin (alligator clips help here) and the -ve (black) cable to the chassis.

turn the key to ON position and see if there is any voltage with the throttle closed (if there is no voltage, you are not hooked up right!)

it should be less than 0.5V (preferably like 0.45ish)

then hold open the throttle...

it should be more than 4.5V

if either of these are not right, then the TPS has been bumped and needs to be reset...

[tinkerbell]

yes i have this problem too
only happens when its cold and there is light throttle applied

also AFAIK - the "over-run fuel cut" only functions when the engine is warm...

pls correct me if i am worng...

[todas**t]

my mates car got a flat spot to after it got tuned. but its funny on a stock ecu for it to happen

[fatboyz39]

As above check TPS AND MAF operations.

I don;t see why a stock motor would have a flatspot unless on of the sensor are goneski.

[aimre]

As above check TPS AND MAF operations.

I don;t see why a stock motor would have a flatspot unless on of the sensor are goneski.

how does one check MAF?

[tinkerbell]

you buy a Nissan or Mitsubish to check the MAF...

[tinkerbell]

have you checked the TPS as described amire? what was the results?

[XB-16-AX]

get ur fuel injectors inpected/cleaned .. and while your at it inspect/test/ replace your fuel pump.

if you have tried all the above that everyone is telling, RE-SET your ECU.

obviously check for CEL codes first prior to resetting. (very last option)

i did this to mine at one stage and solved it. and never came back.

[aaronng]

get ur fuel injectors inpected/cleaned .. and while your at it inspect/test/ replace your fuel pump.

if you have tried all the above that everyone is telling, RE-SET your ECU.

obviously check for CEL codes first prior to resetting. (very last option)

i did this to mine at one stage and solved it. and never came back.

I would have checked for codes and reset the ECU first. LOL

[aimre]

I would have checked for codes and reset the ECU first. LOL

Well the check engine light hasnt ever come one, so im guessing it dont have any codes to throw out.

Ill check TPS maybe tomorow if i got time.

thanks for the help

[XB-16-AX]

CEL light should go on when key is turned then after a sec or so it should switch off..

if ur CEL light never turns on, then possible bulb is dead or connectivity from ECU to cluster has been cut, damaged.

Its important and critical to have the CEL light working, as this will help greatly with troubleshooting engine faults. - well at least a good start to check!