120 1KZ rough start/idle

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

The big brass one on the plastic elbow is the intake air temp sensor (next to it with the vacuum hose connected to the throttle body via a plastic damper)
Said it before and I'll say it again the 1KZ does not have a MAF (mass air flow sensor) it has a MAP (manifold absolute pressure sensor).

As pradonut said, I'd be checking the glow plugs are operating - i.e. battery voltage at ign on and on still for around 1-2 min after starting. Check the fuse and the relay if not.

Ades

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Id be checking battery voltage as well while cranking. Mine seemed to turn over ok but some mornings would choof a bit of smoke and took a second more with the key turned. I checked the battery and was showing correct voltage so didnt think it was the issue until I took to battery world here in Penrith and he checked it while cranking and it was dying in the arse so I bought the biggest I could fit in which for memory was a 780 cca?? The next morning hit the key, was the like the old girl had a new lease of life. Spun over super quick and no black smoke (well not like it was anyway)....Cheers Steve

[mackayvx Advanced Member Find all posts View Profile Close mackayvx]

I recently had the exact same problem.
The starter motor was slow cranking and the motor had a rough start up.
Replacing the starter improved things a little but i still had the problem.
I got the injectors tested and one of them was stuffed.
$407 later I had new injectors and glow plugs and its been perfect since.

My glow circuit shows 11 odd volts for 18 seconds - any thing more than that is a bonus.
Im not sure where the 1-2 minute figure came from.

[scottkz Senior Member Find all posts View Profile Close scottkz]

Air intake sensor could have a bearing on cold starts....
But injector lines are the most likely issue

[allfie1968 Lurker Find all posts View Profile Close allfie1968]

ok back to drawing board , cleaning MAF sensor didn't help cold start today . have noticed that there is no pressure between primer pump and fuel pump I shut engine off after it settled down and pumped fuel up , started fine ???????? any ideas

[allfie1968 Lurker Find all posts View Profile Close allfie1968]

I will check glow plug circuit and load test battery ?

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Sucking air ??.... Cheers Steve

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

Maybe people should read all of the post including it's title before they get upset about people asking questions. .

Its been a while since the do a search brigade almost made the forum a misery. Lets hope its a one off.

White smoke = unburnt fuel
The puff of blue is probably a little valve stem leakage nothing to worry about.

My money will be on the glow plugs or its circuit.

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

If you suspect an air leak in the fuel system get a length of clear pvc tube and put it in place of the fuel hose between the filter and the injector pump. Prime the fuel system and run the engine, look for a stream of bubbles in the hose. There may be some initially but it should run clear shortly after starting.

Ades (I'm a diesel mechanic)

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

ok back to drawing board , cleaning MAF sensor didn't help cold start today . have noticed that there is no pressure between primer pump and fuel pump I shut engine off after it settled down and pumped fuel up , started fine ???????? any ideas

It's not a MAF sensor... ffs..

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Its been a while since the do a search brigade almost made the forum a misery. Lets hope its a one off.

White smoke = unburnt fuel
The puff of blue is probably a little valve stem leakage nothing to worry about.

My money will be on the glow plugs or its circuit.

I recently had the exact same problem.
The starter motor was slow cranking and the motor had a rough start up.
Replacing the starter improved things a little but i still had the problem.
I got the injectors tested and one of them was stuffed.
$407 later I had new injectors and glow plugs and its been perfect since.

My glow circuit shows 11 odd volts for 18 seconds - any thing more than that is a bonus.
Im not sure where the 1-2 minute figure came from.

Depends on the type of glow plug, not sure on the 1hd but the 1kz ones are ceramic and glow for longer (controlled by the ecu and temp dependant).

[iantz Avid PP Poster! Find all posts View Profile Close iantz]

It's not a MAF sensor... ffs..

Ok then. Technically it's not. However, the MAF and MAP serve a very similar purpose, right? The MAP provides the data upon which the ECU can determine mass airflow rate if i'm understanding things correctly. That's essentially achieving the same thing as the MAF then.

What remains unanswered then is whether the MAP ever needs cleaning or not. Mine was certainly filthy. I suspect all sensors could do with a cleaning occasionally.

allfie1968 - if you're losing pressure in the fuel lines then that's probably the the issue. Hopefully Adrian can help you diagnose the problem.

[scottkz Senior Member Find all posts View Profile Close scottkz]

[QUOTE=iantz;473237]Ok then. Technically it's not. However, the MAF and MAP serve a very similar purpose, right? The MAP provides the data upon which the ECU can determine mass airflow rate if i'm understanding things correctly. That's essentially achieving the same thing as the MAF then.

What remains unanswered then is whether the MAP ever needs cleaning or not. Mine was certainly filthy. I suspect all sensors could do with a cleaning

It's the intake air temp sensor

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Ok then. Technically it's not. However, the MAF and MAP serve a very similar purpose, right? The MAP provides the data upon which the ECU can determine mass airflow rate if i'm understanding things correctly. That's essentially achieving the same thing as the MAF then.

What remains unanswered then is whether the MAP ever needs cleaning or not. Mine was certainly filthy. I suspect all sensors could do with a cleaning occasionally.

allfie1968 - if you're losing pressure in the fuel lines then that's probably the the issue. Hopefully Adrian can help you diagnose the problem.

A MAF sensor measures air flow rate which the ecu interprets as mass air flow into the engine and is pretty accurate. It's one of the reasons common rail engines are so clean on exhaust emissions (comparatively) and have much better fuel economy.

a MAP sensor merely tells the ecu what the intake pressure is. The ecu has no idea how much air is entering the engine apart from a ball park figure written into the fuel map - which would vary with revs and load. In this case the ecu relies on the MAP sensor (and air temp sensor) to increase fuel injection quantity to increase power, and is really just an electronic version of an anti smoke device on a mechanically injected engine, i.e. the ecu won't raise the injection quantity until it sees full boost.

Some oil in the line to the MAP sensor or in the damper or the sensor itself would be unlikely to cause issues, if the intake was badly blocked with carbon and oil and some of that gunk got up the line and blocked it then that would cause a lack of power issue, not cause a cold start problem.
MAF sensors are very sensitive and need to be clean in order to work correctly but that's not the case with a MAP sensor.

Losing pressure in the line is normal, when you pump the primer it forces fuel into the injection pump and out of the leak off valve and back to tank.

An air leak can cause the OP problem but I'd check the glow circuits first.


Have I bored you all enough now?

Cheers

Ades

[mackayvx Advanced Member Find all posts View Profile Close mackayvx]

Depends on the type of glow plug, not sure on the 1hd but the 1kz ones are ceramic and glow for longer (controlled by the ecu and temp dependant).

Sorry about that. I should have said the work i did was on our kz prado. The tropy is the new ride. No probs with the 1hdfte!