warm starting issues

[92ThoStro]

Having problems starting after it sits for about 2 hours infrequently. A few times a week. 2003 b15 sentra qg18de.

My theory is the battery but it tests fine. Original battery with 59K miles on the car.
It does have a.lot.of fuzzy corrosion on the negative terminal even though I have gold connections. I have anti corrosion stuff on it and the felt liner.but it doesn't stop it.

It won't start on the first turn when it happens. But starts right away on the second turn.

I redid all the major wiring with 1/0.and 4AWG for the fuse box but the problem existed since I got the car at 40k.

Not really an issue more like a minor inconvenience. But figured this would be a good place to get it diagnosed.

Thought I better add that when I roll my windows down my headlights dim until I let the button go

 

[eric001]

This is just a wild stab in the dark, but could it be a fuel line issue instead of electrical? Maybe it just needs a little help getting fuel into the cylinders before it can start. IANAM, but I've seen this pop up with a 72 Ford that tends to run a little hot.

If that helps, wonderful... if not, I'm sure there are much more qualified folks around here who can give you a better suggestion!

 

[92ThoStro]

I always let it sit on accessory for a few seconds to let the fuel pump kick in. Instead of going straight to start. I get no codes or anything either.

I know older vehicles the fuel would vaporize in the lines but new vehicles don't have this problem.

How do I go about testing the fuel lines and pump myself?

Spark plugs are those nice platinum 100,000 mile plugs I put in. The car came with original plugs. Car was 9 years old with original plugs. So it isn't the plugs either.

Also would like to mention every now and then instead of failing to start the engine starts up on very low RPMs and dies in about 2 seconds. Then starts up right away. This is very infrequent.

My vacuum lines look good. I have a very clutter free and clean bay since I removed a lot of useless stuff. All lines have protectant on them and are.not cracked or loose. Engine temp is always normal.

 

[SaintsNSinners]

Im guessing vapor lock... If fuel gets hot enough it will vaporize.... may want to check your fans, thermostat and radiator... If the engine gets to hot it will vaporize the fuel at the rail

 

[remauto1187]

Having problems starting after it sits for about 2 hours infrequently. A few times a week. 2003 b15 sentra qg18de.

My theory is the battery but it tests fine. Original battery with 59K miles on the car.
It does have a.lot.of fuzzy corrosion on the negative terminal even though I have gold connections. I have anti corrosion stuff on it and the felt liner.but it doesn't stop it.

It won't start on the first turn when it happens. But starts right away on the second turn.

I redid all the major wiring with 1/0.and 4AWG for the fuse box but the problem existed since I got the car at 40k.

Not really an issue more like a minor inconvenience. But figured this would be a good place to get it diagnosed.

Thought I better add that when I roll my windows down my headlights dim until I let the button go

Could you define the above statement? Is the starter spinning the engine over when you turn the ignition to start position? Or is the engine spinning over but does not start until the second try? There is a schrader valve on your fuel injection rail for testing the fuel pressure with...a fuel pressure gauge.

 

[92ThoStro]

That is one of the things I came across. But thought that was.more.common in older cars. My engine.temp on the dash is always steady and low. I have this problem in winter and in the summer. My fans are good.but I have never checked.to see if the thermostat is working properly. I will start there. Thanks.

 

[92ThoStro]

It makes the noise like it wants to start but it doesn't. It just keeps cranking. But if I let go of the key and then try again it starts right away. On occasion instead of not starting it will start with very low RPMs and sputter out in seconds. Sort of like when you add seafoam to a vacuum line too quickly.

Also if I pull the brake.booster line the car dies. IIRC shouldn't it be able to idle.through that?

 

[jkaetz]

Vapor lock is extremely rare on modern engines. Check for fuel pressure with key on but before your first start. If it is good, your fuel system is fine. Have you checked for vacuum leaks? A big enough leak will cause a stall but typically it will cause problems all the time not just when warm. To check for a leak, start the engine and then spray some throttle body cleaner around various vacuum lines. If there is a leak the engine RPM will increase as you just introduced some extra fuel through the vacuum leak.

 

[eldirector]

My wife's Saturn (has a Honda engine) does nearly the same thing, and always has. Appears to be related to a low voltage situation, but I have never nailed it down. Normally starts fine. Rarely will crank for several seconds before starting. On occasion, will crank fine but not start. A second try ALWAYS works.

From several troubleshooting attempts, it appears that the injectors do not always fire correctly at start up. I don't know if it is them, the computer, or a fuel pressure problem. The dealership could not find anything, either. My wife claims that a tank of premium gas will fix it for 2-3 months. I'm skeptical. Replacing the battery (and cleaning the terminals) seemed to fix it for about a year, but the problem came back.

 

[Leo]

Fuel injected cars avoid vapor lock type problems with a check valve. When that check valve fails the fuel vaporizes and that vapor has to be flushed out before fuel actually goes out the injector nozzles. (A weak, sputtering restart is also a symptom) That check valve was mouted to the fuel pump on the old injected Datsuns. I do not know where the check valve is mounted today. The man that spoke of the test port is correct. With a gauge on a running engine, note the pressure and shut off the key. There is a spec for how long that pressure needs to be maintained. If it goes down to zero right away, the check valve is suspect. Good Luck

 

[PaulF]

There are several variables in play here, but it is always good to start with the basics. A gasoline engine needs to be free to spin (So far, so good), needs to have good compression (Still OK), and needs to have fuel, spark, and air.

-Fuel. You could be having a fuel issue, the engine needs a certain volume of fuel delivered at a certain pressure. You may have a bad fuel pump or relay, or the pressure could be bleeding off at the rail (check-valve failure). You won't know for sure unless you can attach a gauge and watch live pressures. This is a strong possibility, and a good place to start.

-Spark. You could be having an ignition system issue. Sometimes ignition coils fail if they get too hot, but if you are not experiencing misfires this is more probably not the issue. It is pretty easy to check spark, so this one is pretty easy to rule out.

-Air. If your car has a drive-by-wire throttle setup you could be having a problem at the throttle valve, or pedal sensor.

-Engine Management. You could be having an issue with the loss of a crankshaft or camshaft position sensor signal. I'm not sure about the Asian cars, but this type of thing happens every day on the cars I see. (I work on "German" cars). Sometimes when a sensor fails it will continue to function on-and-off for a while. The cars I work on can handle losing a crankshaft position sensor signal while the engine is running (it uses other signals to determine crank position), but will not start if it can't see a crank signal. These cars will set fault codes, which can help to point us in the right direction.

Is the MIL (Malfunction Indicator Lamp/Check Engine/Workshop Light) illuminated? Have you checked for trouble codes?

If you're in the Indy area I'd be glad to take a look at it if you get stumped/bored/mad.

-Paul