Lack of power in engine

[Sawdusted]

Guys, hope you can help me solve a problem. Car in question is a 2001 Nissan Sentra SE with a 2.0L engine. BTW, it does not have any CEL or SES codes.

On cold start ups in the morning and sometimes when the car has been parked for an hour or so, it sputters when first started. Idle is erratic and sometimes RPM drops low enough that engine dies. When I try to step on the gas pedal to give it some gas, I have to do it very gently, or the engine will die. Usually after driving for a few minutes, the car can idle on its own.

Right after I move off, engine usually sputters a little, bucks a little and hesitates on each low gear change. When I step on the gas, engine is very slow to respond, even if I floor it.

I had this problem last year too, right after I changed the battery. It miraculously returned to normal after I think I drove over a bumpy road. Recently I had to disconnect the battery for some electrical work and the same thing happened on re-connection.

I have done the idle air control valve re-learn procedure but situation has not changed. Could this problem be due to a out of spec mass airflow sensor (MAF) or a throttle position sensor? I would like to solve this problem as soon as possible as I am going to take the car out for a road trip.

Thanks,
Julian

 

[Clevy]

Fuel pump,fuel filter.

 

[Sawdusted]

Fuel pressure at rail is within spec. Problem just happened overnight. Driving fine one day and the next time I reconnected the battery, it was running rough. And it miraculously recovered overnight the last time too.

Faulty fuel pump would be a gradual thing right?

 

[nthach]

I'd check for spark as well. COP can go bad like traditional systems can.

 

[Warstud]

Originally Posted By: Sawdusted
I had this problem last year too, right after I changed the battery.


Check for corroded battery cables...also may be time for new plug wires and plugs.

 

[chad8]

clean your MAF or replace it . very common on your car.

 

[Chris142]

Ignition coils fail often on those cars too.

 

[71Chevyguy]

Had a bad MAF sensor create that scenario many times in the past. Would not hurt to clean it or tap on it to see if it makes a difference. Assuming all your basic maintenance is up to par.

 

[Sawdusted]

Thanks for the replies guys. Looks like I will be busy tomorrow checking.

 

[Clevy]

Originally Posted By: Sawdusted
Fuel pressure at rail is within spec. Problem just happened overnight. Driving fine one day and the next time I reconnected the battery, it was running rough. And it miraculously recovered overnight the last time too.

Faulty fuel pump would be a gradual thing right?


Not really. Fuel pumps either work or they don't in my experience. You can have adequate pressure however when demand for fuel increases the pump may not be keeping up,causing the issue.
Just spitballing though.
If you are gradual with the throttle the fuel pressure doesn't get a major pressure drop however if you floor it the pump can't keep up.
Maybe.

 

[05LGTLtd]

As mentioned check coil packs, verify voltage at MAF, check you battery cables and ground contacts. Clean TB, check idle control valve for carbon as well.

For good measure run a shot or two of heet through the tank. Also because of the age of the car I would not rule out a exhaust constriction magnifying another small problem.

 

[spk2000]

Maybe a vacuum leak

 

[punisher]

Not specific to Nissan.......If you suspect a MAF, unplug it, cycle key a few times to get the PCM in failure mode and go for a drive.

As far as causes I have seen MAFs, ACT, ECT, O2 SENSORS, harness concerns, bad fuel, clogged injectors, all cause bogs and bucks.

A Bluetooth OBDII connector is cheap. Software works on X86 and Android devices. When an engine acts up, something like fuel trims or some other PID should give you a clue. Only jobs that made me pull out my hair were problems caused by actual bad PCMs, or PWR/ground concerns concerning the PCM. Sucks when a patient cant tell where it hurts.

 

[mikered30]

Originally Posted By: 05LGTLtd
check you battery cables and ground contacts. Clean TB, check idle control valve for carbon as well.


X2, also take it for a hard drive on the interstate.

 

[TechnoLoGs]

Originally Posted By: mikered30
Originally Posted By: 05LGTLtd
check you battery cables and ground contacts. Clean TB, check idle control valve for carbon as well.


X2, also take it for a hard drive on the interstate.


May I ask why bad grounds could cause the lack of power?

 

[TFB1]

Originally Posted By: TechnoLoGs
Originally Posted By: mikered30
Originally Posted By: 05LGTLtd
check you battery cables and ground contacts. Clean TB, check idle control valve for carbon as well.


X2, also take it for a hard drive on the interstate.


May I ask why bad grounds could cause the lack of power?


Probably won't, just sounds good... If they are that bad, it likely won't start at all...

 

[Sawdusted]

Thanks guys for the the info.
Just an update on what conspired this last week.

Family and I took a 800 mile road trip, 400miles each way. On the way there, at lower gears, it kept sputtering or misfiring to a certain degree. At highway speeds, anywhere from 50-70 mph, the car would slow down between 3-5 mph for about 10 seconds, then speed up again (cruise control on) as if I had let off the gas for a few seconds. This would happen once every 2-3 mins consistently.

On arriving there, I pulled codes from it and there was P0300, P1448 P0450. and 1 more other code which I cannot remember offhand. I drove around the destination with the power robbed condition for a few days.

On the return journey, I decided to clear all codes right before setting off for the 400 mile return. It stumbled for the first few minutes but when the engine was hot, it ran beautifully.

No problems now, even when cold. Accelerates like it should. Maintains highway speeds. No misfires. No stalling. Idles fine. Drove like it did before I disconnected the battery. Don't know if I should do any more diagnosis.

Thought anyone?