03 Sentra Extremely hard to start, loss of power during acceleration

[birdman3607]

Gentlemen,

First time poster here just joined at the recommendation of a good friend/ASE Master Technician with 40 years experience. Beautiful site with plenty of information!

2003 Nissan Sentra started off with loss of power/compression upon beginning of acceleration. Slowly over weeks began dying at idle but cranking back up with same loss of power during initial acceleration. Slowly a few more weeks and the vehicle will barely crank up. To get it to crank you must pulsate the accelerator pedal and it may crank before killing the battery after about 3-5 minutes of cranking. Then you must hold the accelerator pedal down a bit so it doesn't kill again.
No DTC's! I started monitoring live view data off of my scanner. In doing so I realized that the coolant temp. was too high. After sitting for an entire day and night then trying to crank it the coolant temp. sensor was reading 80 deg.F, while the IAT was at 67 deg.F. While cranking before the vehicle started the coolant temp. went up to 137 deg.F, IAT still at 67 deg.F. After seeing this I decided I need to change the coolant temp. sensor. I also went ahead and cleaned the throttle body and verified that the coolant level was full. Back to live view on the scanner now the coolant temp. sensor was reading 137 deg.F! So it appears that there may be a circuit issue and I am going to track down and check all of my grounds. This is where I am with it right now. I originally thought maybe EGR stuck open, not the case. Also maybe Cat. Conv. bad or plugged but verified correct O2 readings on live view.

My question is has/does anyone have experience or experienced the same issue and what was your fix? Thanks in advance for any and all help. I will post as I continue to diagnose and of course share if found the fix!

[milto0n]

Generally, I like to try basic maintenance and "easy" repairs first. This g20 I was working on needed a tune up like there was no freakin' tomorrow. Plugs, wires, cap & rotor made a day and night difference. Scrubbing the throttle body and with cleaner and running injector cleaner with good gas also dialed it in. I would start with that first. You should also do a visual inspection of all vacuum hoses and what not to check for a vacuum leak.

[B13_Red]

You tried to start with A) coolant sensor disconnected (high ohms, low temp), and B) short the sensor input to the ECU (low ohms, high temp)- just for experimental?

Maybe check the IACV air passage for gunk, and make sure it actuates with a 9V battery. I had similar issue with my '92 Sentra... and it was the IACV getting stuck.

Let us know the outcome.