1996 Prado 1KZ TE Rough Idle with hunting and insane amounts of black smoke

[W3LIAN]

Hello everyone

I'm new to the forum and this is my first post. Ive had a 95 Prado fitted with a 1KZ for almost 18 years now. For full disclosure, I've had the engine replaced once due to a cracked block earlier in its life. Over the last 6 months, I've had recurring issues where the car on idle hunts and shakes alot while producing insane amounts of black smoke similar to what would happen in a diesel runaway. Sometimes the engine would cut out. I've replaced most vacuum pipes, injectors and their solenoids twice among other maintenance work and the problem has persisted. The shop I've trusted with my car seems to be running out of options as to why the issue is occurring and its giving me grey hairs as its my daily

I'm seeking assistance as to why this may occur, as it looks like I'm facing a full rebuild to salvage my ride.
Thanks in advance

 

[Shayne]

Search the forum for spill control valve ,its becoming a common issue .

 

[W3LIAN]

Thanks fine guru.....
Should i ask the shop to look into it?

 

[Tractionman]

Only if you want to part with money.

 

[W3LIAN]

so im better off doing it myself?

 

[Tractionman]

W3LIAN, If that is the problem and you are capable - yes. The only way of knowing it is done properly.
Of course if you know the shop, have found them reliable, and dont mind paying them, by all means let them do it.
I would say get diagnostics done first to confirm the problem, I'm surprised your shop hasn't done this already ?

 

[Shayne]

1996 1kz-te Prado RX

Hi team, just a quick post to welcome myself. Absolute novice with no idea but am loving the learning and troubleshooting with the help of this forum. I have a 1996 1kz-te Prado RX which loves to stall when the mechanic/sparky isn't here, and won't stall for them when there are. Anyway, will...

www.landcruiserclub.net

 

[W3LIAN]

Yeah I'm not sure, most of their focus was on the injectors, but i have instructed them as so and since the car was already there they will

 

[Tractionman]

Hmm...Id have thought that if their focus was on injectors, they would have done a diagnostics check first anyway to get a full read out, without going any further at that stage.
What exactly did they do re injectors, - or anything come to that ?

 

[W3LIAN]

They re did the solenoids with new ones, didn't stop the smoke so they replaced all of them, and also re did the fuel lines too

 

[Shayne]

Did they change this on the fuel pump ?

 

[Tractionman]

So what about the injectors they were focussed on ?
Beginning to sound like parts changers with no knowledge or diagnostic equipment.

 

[karl2000]

How about the bonnet catch

 

[Tractionman]

Long or short version ?

 

[W3LIAN]

so I've just had a discussion with the shop, they checked the pump, it's good. The SCV is also working well. The issue seems to have been with the wiring to the SCV, which had previously been botched. I will test the truck out, will change the SCV if it persists

 

[Shayne]

We would like to help but because its in a garage and you can only relay what they tell you to us its difficult .

The SCV controls how much fuel is injected and they are known to fail eventually hence it was my first thought because black smoke is over fuelling .

If its not the SCV then it can only be dirty sensors not giving the ECU correct info or your ECU is damaged .

See the pic i posted , show it to them , tell them to pull the little cap off the top of it with pliers , undo the lock nut and turn the tiny centre nut all the way down anti clockwise . If i'm right the black smoke will stop but your truck will lack power .

Try it and come back to us .

 

[Tractionman]

As Shayne says, difficult as you are relaying what they want to tell you, without any evidence/proof of any diagnostics. If it is the wiring that they say has been botched, you will be wasting more money on replacing any scv/s that could be good.
Do you have 2 on that engine, red and green, or just the 1 ?
Surely, if they know the wiring has been botched, why haven't they addressed that to remove it from the guessing game they are playing, that you are paying for ?
Your shop does not give me any confidence of their capabilities at all !

 

[Shayne]

1KZ-TE has only one . With spanners handy i can reach in to remove that cap and adjust the spill timing in about one minute job done .

 

[Tractionman]

Worth a try, if that time involved.
As the wiring is botched, the scv may not be getting the proper signal through.

 

[Shayne]

From the ops first post the car was running fine since new engine , back when ?

And 6 months ago it developed an electrical fault resulting in over fuelling . The only possibility i can think of outside of electrics , and its a long shot , is the turbo wastegate is rusted shut so at tickover sensors are telling the ecu boost pressure is reached and the ecu is telling the scv to add more fuel .

Or your intake is blocked - fuel can't burn without air .