I have a 91 Sentra 140GX, the car has a flat spot as when i take off it stalls then picks up speed but i have to play with accelerator to take off. Also the idle is over 10000rpm and we canot get that right even the carburettor peoples tried but say it cannot get a CO reading. Please assist
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Sounds like you have a dirty mass air flow sensor...it is located in the middle of the mass air flow tube...Pull the air filter off and try squirting some cleaner made for it..if that doesn't work change it out..not a difficult job normaly one electrical connections and four bolts..good luck.
check the TPS sensor with a volt meter to check for drop outs as you manually move the throttle. this is like a rheostat dimmer like you might have in a house to dim the lights. the ribbon wears out and can cause a flat spot.
Check vacuum leaks , by spraying carburator cleaner around intake manifold gasket and vacuum hoses connections . See if engine picks up the idle speed while you doing it , and if it does , locate leak and fix it. Most common , intake manifold gasket brakes.
2006 model?? dealer only encrypted software ,my advice is if it runs ok when driving normal then leave well alone ,this flat spot could be present to allow for something in the normal running ie tuning to keep the economy up ??
I am assuming you mean that there is a particular RPM when you don't have as much power as you think it should?
The first thing I always suspect whenever there is a flat spot, is one of the valves that is supposed to turn on and off at different ranges.
Some of them to check include the EGR, gas tank purge valve, and the PCV. The ERG can be checked by pulling and plugging the vacuum hose to it. The it should stay cold. With the hose connected, it should get hot when revved up a bit. If that is good, then it is not frozen. So then drive it while plugged, and see if that helps? It could be staying on at high speed, when it is supposed to cut off. Similar checks with the others. If if things change when disconnected temporarily.
If it's also a "wub wub" sound, look into your tires. I had a flat spot in my front driver's side tire that made the "wub wub" sound. Couldn't hear it well if driving slowly, but as I would pick up speed, the "wub wub" would increase in frequency and volume.