Hi I have a 98 GXE Auto with ~ 29k miles and when ever it's cold it is very difficult to start the engine. It will crank but as soon as the engine fires up the rpm will drop to about 300 and then if I'm lucky it will run rough for a few seconds and idle normally. Most of the time it'll just stall again right away. This does not happen when the engine is warm.

I've change the plugs and the air filter but the problem still persists. Anyone had a simular experience and found a solution? Bad coolant sensor? Perhaps no residual fuel pressure? TIA

-dingster

 

You can try this: just put fuel injector cleaner in it.
Back in November, I had that problem too; when i first start it it would rev high and then gradually go down to 0 rpm (this is stalling right?) . I bought the F.I.C. just to see if it would give me better performance, not much difference there but it did stop my car for stalling. The one I bought was from Shogun. Lately my car is starting to rev high but doesnt go down to 0 rpm, so I guess its time for another bottle.
Hope this helps

 

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.

 

Perhaps the fuel rail lost its residual pressure. Next time you have a cold start situation, try this experiment. Turn the ignition key to ON, wait 15 seconds, then turn the key to START. This brief delay gives the fuel pump some time to build normal pressure. If your car starts readily and runs well after this brief delay, that will confirm this fuel pressure hypothesis.

Possible causes loss of residual fuel system pressure include
- an external leak anywhere in the fuel loop
- a leaky check valve
- a bad fuel pressure regulator
- one or more fuel injectors which sticks open