philpoe

iTrader: (4)

Hi all,
I'm having an intermittent starting problem with my car.
The other day, it was sort of cold, and the car wouldn't start. It seemed to be cranking but not catching. I pulled my wifes car up, wedged the pedal a tad and tried to jump it. No luck there either. A few minutes later I had her sit in her car and rev it good and the car managed to start with a very rough idle at 1200rpm or so. Lots of white exhaust.
I made my way to work, and the car seemed very sluggish. When I pulled in and shut it off it started up fine. I Took it to the dealer who stated that the battery was not providing normal amperage, and they replaced it. The car seemed fine, but it's been cold a few times since and the car still has a very rough initial idle and seems about to stall.
I can imagine that the idle will rise above normal on a cold day to build up temp quicker, but I've never seen it get that rough. If the car gets within normal temp ranges, it drops idle to 700 or so, and starts up fine.

Any help here?

possible useful tidbits:
The cars ecu probably reset with the battery change, but I have no power mods besides a UDP.
The car was sitting with windows down and sunroof open in a windy driveway several times (roof open only once) so it's possible the car was colder than normal.

Krog

Maybe and this is my theroy only did ya use cheap gas I notice a signifacant difference in startabilty between 87 and 93 octane. I would have a hard time starting the car with 87 would stall and run ruff for first min but no problems when i used 93 so I use only 93 now. maybe it helps maybe it doesn't worke for me though

dch95

You mentioned that the "ecu probably reset with the battery change". Did you have a code? Better yet even if you don,t have a light try pulling up a code and see what happens. You may actually have one stored. Post back with results.

Daniel B. Martin

Your fuel injected engine has an Engine Coolant Temperature Sensor. This sensor sends a signal to the Engine Control Module (the computer). When the ECTS sends a "cold engine" signal the ECM responds by instructing the fuel injectors to deliver a rich mixture. The rich mixture helps a cold engine to start and run smoothly during the warm-up period. This is similar to the operation of the choke on a carbureted engine.

There are other problems which cause cold starting and driveability problems, but the ECTS is the first thing to check. This can be done with an ohmmeter.

On the 4th Generation Maxima engine the Engine Coolant Temperature Sensor is located in the water outlet tube close to the engine end of the upper radiator hose. There are two sensors in that vicinity. The one nearest the hose is for the dashboard temperature gauge. The ECTS, the one you're interested in, is adjacent to the the gauge sending unit. There is a good picture of these sensors in the Haynes manual on page 3-7.

With the engine cold, disconnect the ECTS and measure its resistance. Reconnect the ECTS, start the engine, and run it until fully warmed up. Stop the engine, and repeat the resistance measurement. The "warm" reading should be a much lower value than the "cold" reading. These are the specs:
Engine coolant temperature 68F, ECTS resistance 2.1 - 2.9 Kohms
Engine coolant temperature 194F, ECTS resistance 0.24 - 0.26 Kohms
(Roughly a factor of ten difference.)

The ECTS is a relatively inexpensive sensor and something the home mechanic can replace without special tools.

philpoe

iTrader: (4)

I always use 93 octane.
I don't have a diag tool to get a code (or is there another way to get the code?)
I'll try to borrow a multimeter to get the sensor measurement

thanks!

Daniel B. Martin

You will also find instructions to do a DTC readout and reset
the Check Engine light at:
http://vbxmaxima.8m.com/ecu.html

The DTC "translations" are found at:
http://vbxmaxima.8m.com/ecudecoder.html