boostedEBP

My car has weird hesitation i cant figure out for the life of me, and it also gets bad MPG

New: Plugs,cap,rotor,ignition coil
Replaced the coolant sensor, FPR seams fine, Ignition timing is mint as with the belt timing...

Some time while tryin the accelerate the car bogs down like it has almost no horsepower , so i tip into the throttle and when it comes alive it'll spin the tires in first gear. Traveling down the expressway it'll have a very slight hesitation, or when accelerating it sometimes does it...now the problem is only on partial throttle not WOT.

Car is bone stock with a D15B7

Car also gets approx 26mpg highway

Possible o2 or fuel pump??

BryanM.

iTrader: (1)

Faulty O2 sensors can make the engine act weird, including hesitation like you described or even like a "dead spot".

boostedEBP

yea it feels like a dead spot...i know its not the tps cuz i checked that...

Im gunna have to try an o2...any other ideas?

Mohsin

i've had the same problem for a while without a cel until it did get a lot worse and now i get a CEL for the o2 sensor / heater. CEL also comes on after 15-20mins of driving, starts to bog and hesistate until CEL comes on and runs into limp mode.

99% its the o2 sensor.

boostedEBP

sounds like my problem...i have no cel as of now

boostedEBP

o2 sensor seemed to be teh culprit...put a good used on in there and it runs good so far hasnt skipped a beat

B serious

iTrader: (1)

The primary O2 sensor is inactive under moderate to heavy acceleration. It is only "heard from" by the ECU for cruise and very light throttle, or idle when the car is at operating temp.

If you accelerate moderately or WOT, the car goes into open loop anyway. Accelerating normally in traffic, you will most likely reach the "moderate" point.

Is your TPS and MAP in good condition? Check them with a volt meter.

TPS should read close to 1V with the throttle closed...and around 4.5V with the throttle at WOT. Obviously, do this in the key "on" engine "off" position.

I forgot what the MAP voltages were exactly. But they should be around 1V at full vacuum, and 4.5V at no vacuum. Again, with the key in the ON postion but the engine OFF, the map should read high voltage. Since the car is off, there is no vacuum, so the MAP thinks you're flooring it.

You can put a vacuum pump up to a manifold line to get the MAP reading at high vacuum (idle or decel).

Good luck.