Weird Cold start engine hesitation

[parry]

Today it was -4 C or 30 F approx. I started the Murano 2003. It started fine. But after about 10 seconds or so, it started to hesitate. The engine was having trouble to keep running I was still at parked position. I waited for it to warm up for about a minute. Then I changed to drive and started in motion, the engine felt under stress or almost like stalling but did not stall. Then the SES light started blinking. I think it blinked for about 8-10 times then went away for a few seconds. Then it started to blink for about 8-10 times. I think it happened about 2-3 times. By that time the engine was warmed up and all became normal. No SES light anymore...

BTW, The mileage is 145,000 kms. Spark plugs have not been replaced yet. I am getting concerned as the winter just started....

Any ideas what it might be? Do you think a air filter replacement might help or? I have never seen the blinking SES before.

[smendoza]

Get the codes read somewhere, if possible. Mine exhibited similar behavior and was giving me a code for a #2 cylinder misfire. Turned out there was a crack on the coil pack/spark plug boot area causing the spark to short to the side of the spark plug wall and creating the misfire condition.

If you can get the code and narrow it down to a certain cylinder, it will make the diagnosis much easier.

[zebelkhan]

I have another theory. It is possible that the cold caused the rubber intake hose to lose its flexibility and when engine was started it was pulled off, opening a very small gap that let non-metered air to enter intake manifold. Once it warmed up, hose became flexible enough to close the gap and problem went away. I would check that possibility.

[parry]

I will check both of the feedback tomorrow. I believe there was a recall and I had got it done on the intake hose a few months ago..

[parry]

I checked this morning and there were no error codes. I am going to check the Air intake hose as well but I doubt that is causing it as the recall work was done a few months ago. It should be good unless the dealership didn't do a thorough job.

Any more ideas?

I am unsure but if someone can point me to the Air intake recall..what exactly did they do?

[njjoe]

Originally Posted by parry

I am unsure but if someone can point me to the Air intake recall..what exactly did they do?

It called for replacing one intake duct and two circle clamps.

Here's a link to the thread that discusses the recall: Intake Air Duct Recall (2003-2007)

-njjoe

[parry]

I just ran another code check while it was cold outside. No SES but there was a code that came up on my OBD reader.

P0301 - Cylinder 1 misfire detected.

next steps?

[zebelkhan]

Your plugs maybe failing then.

[parry]

I have replaced the spark plugs today and plenum gasket. Idle re-learn was also done. Will report back. Waiting for a cold day now. fingers crossed

[parry]

Update- The temperature dropped today and I start getting the hesitation again upon cold start. Today the codes came up as

P0301- Cylinder 1 Misfire detected and
P0306- Cylinder 6 misfire detected along with blinking SES light(when the vehicle has just started to accelerate from park position).

It went away after a while and all became normal. The Pending codes go away after a few ignition starts throughout the day..

According to this thread Warhammer mentioned that it could be a Bad Head gasket..opinions? Is that the same gasket as the plenum gasket that was changed during spark plugs replacement?

Someone also mentioned to ask the dealer to run compression test on all cylinders..

Unsure where to start..expert opinions required guys..

[zebelkhan]

No. Head gasket problems will not give you these symptoms. The plenum gasket that was changed during spark plugs replacement is the intake manifold gasket.

The only thing I can now think of is that the ECM is not sensing the cold temp and is not increasing the fuel amount to make fuel/air mixture rich for the cold start. So fuel mixture remains lean and engine hesitates. Not sure how to fix it though.

[parry]

makes sense..So does that mean following these steps would help?

Service Engine Soon Light came on

[zebelkhan]

Other than the what njjoe said about a possible bad air/fuel mixture sensor nothing else in that thread seems related to the problem you are having. I don't think it is the A/F sensor that is bad in your case because then you would be having problems all the time. But if you have this issue only when it is cold, something is not sensing the correct air temp and or ECM is not interpreting it correctly so the "chock", as it used to be called on non fuel injected engines, never comes on. Maybe that could be reset by dealer.

[parry]

Update- I took it to the dealer. They were able to get P0301 code as well. But the guy said that it could be anything and it is a soft code/fault. It goes away after the ignition is turned off. A hard fault stays in the memory with SES ON. In this case the SES blinks and goes away. The code goes away once the engine warms up in about 5 minutes. He said it could mean anything and suggested to wait until it gives a hard code. Only then they could further narrow down what the problem is. He had a feeling it could be one of the solenoids but didn't want to start making any changes until there are hard faults. Surprisingly, althought they had said it will be $120 diagnosis fee. They didn't charge me anything for this diagnosis.

Is it safe to leave it as-is and keep driving or? Anything else I could do? 2nd opinion? ANy help would be appreciated. I am concerned :-(

[turbizzy]

A blinking SES light always means the ECM has detected a misfire and is misfiring during the blinking. Once the blinking stops, the misfire has ended. Many things can cause a misfire such as faulty plugs, coils, injectors, sensors, poor compression, bad fuel, intake/exhaust leaks, etc etc. The purpose of the light blinking is to alert you that during misfires, the catalytic converters are suffering severe damage from unburnt fuel. Theres not really a solid one thing that could cause a misfire so most of the time, I use my experience with Nissans to determine which route to take.

In my experience with Muranos, you don't usually see cylinder misfires with the VQ35s too often. The earlier VQ30s in the late 90s Maximas were notorious for faulty coils but once they switched over to the 3.5L in 02+, most things i've seen cause a misfire were either a loose intake duct, faulty MAF sensor, faulty coil, faulty spark plug(s), faulty cam sensor(s), poor fuel pressure, intake restrictions or plainy poor fuel.

You guys all have good theories up there but at this point its all speculation as we can't see the vehicle. And diagnosing an intermittent problem can be costly especially at a dealer unless we can absolutely make the problem reoccur as we wish. Since he mentions that the problem occurs mostly when its very cold, no hard codes stored and the unusual cylinders 1 and 6 misfiring (separate banks), im wodering if it has something to do with the fuel your running. Maybe its freezing up and/or your fuel pump is working harder to reach operating fuel pressure (typically 50psi). Unfortunately you can't really test your fuel pressure unless you install an in-line fuel pressure gauge which the dealer has, and monitor the pressure during your misfire. Who knows, maybe the pump could also be going bad?

If it were me trying to diagnose the problem, i would start with the basics. Test the battery and charging systems since they take major abuse when cold and hot. If those check ok, check battery cables, ground cables, check fuel pressure since its the easiest thing to to versus a compression check. If all that looks ok, move onto checking the ignition coils for any signs of metling/heating up/cracks/etc and swapping them with another cylinder (keeping track of which i switched with), checking spark plugs for proper gap and signs of wear/damage, also swapping plugs with other cylinders, compression check while plugs are out. Button everything up and wait until it happens again. If the misfire changes to another cylinder then that coil and/or spark plug could be bad.