Miss fire on hot start

Hey
First time posting.
I have a problem with my 06 d40 stx 2.5. after a 25min drive when I go to start it again It has a miss fire that only lasts about 2/4 sec and than clears up.
Things I have tried to solve the problem
YD25.com chain kit. (Had chain rattle)
Removed cat.
Cleaned maf.
Reset ecu and fuel pump.
Fuel filter.
Injector cleaner

I'm thinking it might have a injector leaking.
Any suggestions would be great. Cheers

I'm wondering - given the age of the vehicle - if the EGR valve is leaking when the motor is hot (so when it heats up, the valve gets a little sticky). Blocking the EGR with a plate near the valve (intake side of the motor, the EGR comes through the gold tube that runs around the front of the motor) might resolve the issue without the expense of a new EGR valve.

Sorry I forgot to mention that my egr is also blocked as I thought that might be it.

That makes it a little tougher. It won't be the turbocharger because during startup it's not spooled anyway. Even if the actuator is not being moved, it won't make a difference during start.

During startup (particularly a hot start) the only things that make any difference are fuel rail pressure, fuel presence and oxygen presence at the right time. This means the suspects for poor starting (apart from a battery that has difficulty providing enough power to turn over the engine) would be limited to:

* Fuel supply to the pump
* Fuel pump
* Crank angle sensor
* Fuel injector harness
* Intake butterfly (yes the diesel has one but not used for the same reason as petrol)
* Intercooler - over time these can be considerably "gummed up" by the oil vapour that comes out of the PCV

Once the engine fires, does much smoke come out?

I did think about the throttle valve as being a early yd25 its vacuum controlled and I thought it might not be opening in time when the engine fires.

If I start it and it miss fires and I give it a little revs it goes straight away.
Also no smoke at all comes out

What about map sensor as that sits in the cooler could be dirty?

Cheers for the help

The boost sensor (sits low on the outlet side of the intercooler) shouldn't be an issue during startup because it's only measuring boost and boost doesn't matter when cranking - the D40 measures incoming air with the MAFS in the intake near the air filter and you've already taken care of that (which is why it was excluded as a possible cause).

Even a failure in the vacuum pump won't affect startup because the vacuum pump is only supplying vacuum to the turbocharger actuator (vane control) and brake booster.

I was thinking about the battery but a poor condition battery would be even worse under cold start because it has to supply the glows as well.

It's a strange one
It's got me stumped at this point. And the fact it only dose it intermittently makes it worse.

Intermittent usually means electrical. Check connections to the pump, fuel rail pressure sensor, injector harness.

Three other very common causes of these sort of failures are:

1) Battery terminals not making good enough contact with battery leads. They can look fine, and my negative terminal looked good, even covered in that blue terminal sealant, but when I loosened it and lifted it, there was corrosion on the negative terminal of the battery itself and only a tiny contact point. Cleaned it and all came good.

2) Earth lead on the side of the engine. Needs to be removed, cleaned and reinstalled, but the protective spray isn't worth using unless you have one that can handle a couple hundred degrees C.

3) Earth point for the ECU. Not sure the 06's suffered from this, certainly the 2010-2012 models did - Nissan painted the surface where the ECU was to be earthed and the screw didn't bite into the metal well enough to form a lasting connection in some cases. Check yours, remove the paint, clean the metal, reconnect the ECU earth, tighten the screw then spray with either paint or battery terminal spray (or brush it on). It should be somewhere near the ECU (above the right hand front wheel against the side wall of the engine bay).

Thanks for your reply

I'll chip away at list tomorow
Cheers

Sounds odd but.... Remember reading in the manual that the engine has to crank 3 times for ECU to get proper start. I have had an occasional problem with it kicking over quickly then running like a hairy goat. Just a thought.

How long dose it run bad for?
I can almost count how many times the cylinder or cylinders that miss.
As it is for such a short time just after crank.
I have tried cleaning the 3 earth points and made no difference.

If it doesn't stall it clears within 30 secs. If you can count the cylinders misfiring maybe an injector. Next time it does it try and remember how many cranks it took to start. If less than 3 maybe similar thing to what I have seen.

Had a bit of break through with this miss fire on hot start.
What I have found is when I go to start the car if I tur the key to the on position and leave it there for 2/3 seconds it won't do it. It only dose it when I put the key in and go straight to crank it. It's like it needs a second to prime. But didn't think they had a lift pump?

I think they have an electric pump of some description. If i turn the key to on in my d22 i can feel a very slight vibration in the gear stick. So you could be on to something there. ...

There is no lift pump the injector pump does all the sucking, perhaps the tank is not venting properly and causing fuel starvation issues?.

There's only the one pump.

The only difference between instant-start and delayed start is how much hotter the glows get. They come on at coolant <= 85C. The fuel pump only operates when the engine is turning, and can produce an amazing couple of thousand psi of fuel pressure at only a few hundred RPM of cranking speed. This is also part of the reason why it takes over 500 amps to turn the engine over by battery!

Things like the SCV should behave better when the engine is hot so I'd suggest it is NOT the SCV at fault. Metallic expansion may affect the injector if there's a bit of cleaning needed.

I'd suggest a can of Liqui Moly Fuel System Cleaner Conditioner and see what happens. At the worst, it'll clean the thing up a little.

Cheers

on my 06 stx, I have to leave the igniton on for a couple of seconds every time I want to start it hot or cold, otherwise it chugs for several seconds, then clears. the glow plug light on the dash tells me when to start it

Never seen it in writing but I think they recommend waiting for the glow plug light to go out, as the ecu does a self test at ignition on.