Hard start when warm!

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09-23-2015, 01:13 PM

msellas

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Join Date: Sep 2015

Posts: 2

Hard start when warm!

*Just as a disclaimer, I'm fairly new to the world of mechanics*

But, it seems that being poor encourages you to learn things on your own.

1999

182,000 miles

Car runs beautifully after it has started - But hard start when warm.

Hey all, I've been smacking myself silly trying to figure out what is happening with our Maxima.

So, back in April of this year, our FPR slowly began to go bad. Eventually the inner diaphragm cracked and so the entire fuel pressure on the rail fell apart causing tons of backfire and random misfire.

At first I had no idea what it could've been, so I decided to start off with changing the spark plugs. I picked up some Iridium NKG's and changes all six. However, when I got to the last ignition coil, I noticed that the coil was snapped in half and was held together by some sort of glue. So, I decided to change that too. After all this, no improvements. I figured perhaps the other ignition coils are bad, so I tested them as per the Haynes Manual, but all they all seemed to be healthy.

So after this I decided to inspect the fuel injectors. After relieving pressure within the fuel lines, I took apart the Upper Manifold and carefully took out each injector. 3 of the six were destroyed. The smaller O-rings were missing and the end caps were cracked. And so I ended up replacing all 6 injectors and the fuel filter (just because) put everything back together, still nothing!

Finally, after some more research I decided to replace the FPR. I started the car, and vroom! Started right up and ran like a champ! $350 later and all has been well for quite some time!

BUT! I now have codes for Knock Sensor P0325 and Ignition Primary 1320, that just keep coming back after resetting them!

...until last month. Here is where the hard start comes in.

Over the course of the month of August, I noticed that my starts were not as crisp as they have been. I noticed that sometimes I had to crank just a taaaad but more than I was used to. Fast forward a month later, and it has become very very difficult to start the car after it has warmed up. On cold starts, everything is perfect, start right up. On warm starts, it cranks, cranks, cranks, and sometimes clunks. Finally after 3 or 4 tries, the engine will finally turn on. It got to the point where I killed my old starter; the entire mechanism inside was destroyed from all the cranking. Finally I replaced it with a new Reman from Duralast Gold a couple weeks ago, but the same problem is still happening

I noticed that after the car is warm, I would have to either apply a bunch of throttle or take out the fuse for the fuel pump; only then will start right up! This led me to believe that I have a rich fuel condition at start up. No other engine codes have come forth either. So after some more research I found out that sometimes, a messed up Coolant Temp Sensor would only send a cold signal to the computer, even after the engine has reached operating temperature, which would mean that the mixture would constantly stay rich. So I replaced this too...and while my start ups have somewhat improved...I am still having trouble restarting after engine has warmed.

I have no idea what to do. My mechanic says it's the knock sensor 100%, but I'm getting mixed answer from people saying that KS won't cause a hard start.

I'm stuck and don't know who to proceed

Summary of Symptoms
Hard start after engine has warmed
Slightly decreased fuel economy
A very small decrease of power during highway acceleration

Engine Codes:
P0325
P1320

Components Recently Replaced
Spark Plugs
All 6 Ignition Coils
All 6 Injectors
FPR
Fuel Filter
Air Intake Temp Sensor
Ignition Switch
Engine Coolant Temp Sensor
Coolant Temp Sending Unit
Starter
(Cleaned Crankshaft Sensor)
(Cleaned Idle Control Valve)
(Cleaned Throttle Body)

Note:
Extra throttle or taking out fuel pump fuse facilitates an easier startup
Battery voltage after operation is around 13.8 otherwise it is at 12.5

Last edited by msellas; 09-23-2015 at 01:23 PM.

09-23-2015, 08:23 PM

The Wizard

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Your mechanic is an idiot. It's 100% not the Knock Sensor.

Although you replaced a lot of the usual culprits, your new part(s) could be failing. The usual culprits for a hard warm start are FPR, bad injector(s), ECTS, and Fuel Pump. I think the only other part you haven't diagnosed/replaced is the Fuel Pump and ignition condenser.

Code 1320 also refers to the ignition condenser. Why it's called a condenser I don't know. It's a capacitor and can be found taped up in the wire loom above injectors 2, 4, and 6....or just hanging free and to the right of injector 6.

Since your MPG's have gone down, this would lead me to believe you have a bad injector or two (sticking open), which would also explain your hard warm starts

09-23-2015, 09:16 PM

msellas

Newbie - Just Registered

Thread Starter

Join Date: Sep 2015

Posts: 2

Quote:

Originally Posted by The Wizard

Although you replaced a lot of the usual culprits, your new part(s) could be failing. The usual culprits for a hard warm start are FPR, bad injector(s), ECTS, and Fuel Pump. I think the only other part you haven't diagnosed/replaced is the Fuel Pump and ignition condenser.

Code 1320 also refers to the ignition condenser. Why it's called a condenser I don't know. It's a capacitor and can be found taped up in the wire loom above injectors 2, 4, and 6....or just hanging free and to the right of injector 6.

Since your MPG's have gone down, this would lead me to believe you have a bad injector or two (sticking open), which would also explain your hard warm starts

Thank you for your response. I totally agree with you, I could veey well have bad new parts.

I too thought I may have a problem with the FPR, so I went ahead and got a new one under existing warranty, and still the same. I also checked my spark plugs after having trouble starting to see if they were wet at all or showed any signs of a rich condition, but all 6 looked perfectly healthy.

I'm leaning towards a a new fuel pump as well; but before I dig into my fuel tank, I'm thinking of running a few more diagnostics. Mainly on the PCV valve and the EGR valves. From my understanding if any of these cease to work from carbon buildup (which at 180K is definitely possible) they can cause a hard start when the car has warmed up.

Any thoughts on this?