1HD-FTE - white-grayish smoke

[Miro]

Greetings,

A problem I've been trying to sort out for some time now, is a noticeable white-grayish smoke out of the exhaust, with a smell of unburnt diesel. The smoke is noticeable while the engine is still cold (for the first few minutes of driving) and primarily while idling. With the engine getting warmer the smoke is less and less, sometimes completely gone (even at idling rpms).

In an attempt to sort this out so far, about three months ago (around 1, 500 km since) I have had my injectors removed and cleaned by a reputable local shop, specialized in refurbishing injectors and IPs. They did knew those injectors are a two stage ones. Their feedback was that the opening pressures of the injectors were a little below the specifications and they did the necessary adjustments. Apart from that, the nozzle tips evidently did need some cleaning and this was done (ultrasonically) as well.

During the above, I asked the technician who did the removal of the injectors (that was in another shop), to measure the engine's compression (although it is not accurate when the engine is cold), and see if there is any noticeable difference between the cylinders. Although I am not very confident of the accuracy of his measurements, he said that on the 2nd and 3rd cylinder the compression was about 1 bar less then the others, which he measured to be around (20 bars). Interesting thing about this is that the engine starts fine, even when fully warmed up (which is when a compression issues are most noticeable from what I know).

Anyway, the injectors were then fitted back, with all the necessary replacement parts, most notably with new (OEM) injector seats. Also, the valves clearance was checked / re-adjusted during this.

And this all had the desired effect... for some time, anyway. The white-grayish smoke (and the shaking at idling) was completely gone. For about a month, all was great, until I had to take the cruiser for a long (4 hours) highway trip. When I got back - to my unpleasant surprise, the truck was smoking again at idle despite the fact it was fully warmed up at the time

Currently, the shaking at idling is mostly gone, noticeable only occasionally during the first minute after starting the truck in the morning. The smoking problem is also accompanied by occasional loss of power.

Also, something relevant is the EGR. While the smoke was gone after the injectors repair, I was able to consistently hear the EGR doing it's job. By hear, I mean a ticking sound from the egr when it opens / closes, at idle and during driving. Not sure if such sound is expected / normal though. Currently the ticking sound from the EGR is sporadic; from time to time. I tested all solenoid and vacuum hoses which control the EGR. They are all good. The solenoids hold and release vacuum (when powered) perfectly.

I got the cruiser about ten months ago, and immediately had it serviced; replaced all filters and fluids. I also had the local Toyota dealer to inspect the truck and diagnose the smoke problem. Long story short - they did not find anything faulty. No fault codes. This was done before the injectors removal. Based on their experience, every component that may be causing the smoke and which they can test, is working normal. What they could not test were the injectors.

So my next suspects in trying to sort this out are the MAF sensor and possibly - the injection pump (although from what I know the IP either works or does not; no inbetweens).

Any thoughts, suggestions or corrections on the direction in diagnosing this problem would be greatly appreciated.

 

[uHu]

The opening pressure of the injectors was changed on the 1HD-fte engine in the 100-series, from august 2001 production in Europe, for the models with water cooled egr. I think the difference is actually not water cooled egr or no, but that engines with water cooled egr also have an array of 6 valves on the intake manifold, blocking the flow for one for the intake valves for each cylinder. This is called "Intake Air Control Valve", and speeds up the air flow into the combustion chamber on low power.
When I recently had my injectors serviced and the nozzles changed, the very reputable diesel experts didn't know of the two versions of the HDJ100, so I had to ask them to set the pressures differently than they planned to.

I also learnt that both the injectors and the injection pump (IP) loose pressure over time, meaning that the IP looses some pressure over time, and the injectors' opening pressure goes down as the springs loose their springiness. They told me that it wasn't uncommon that after a customer had had the injectors serviced, and put them back i place, now with a higher opening pressure, the next thing they got in for service would be the IP, which couldn't anymore supply enough pressure.

Anyhow, here are the specs, taken from the FSM:
Opening pressures, in kPa:
first stage pressure, early version: 17,162 - 18,142
first stage pressure, EGR-cooling: 17,650 - 18,630
second stage pressure, early version: 33,539 - 35,500
second stage pressure, EGR-cooling: 27,460 - 28,440

BTW, have you had the intake pipes cleaned? The EGR deposits a lot of soot and oil inside the pipes, which reduces air flow, and coats sensors and valves.

 

[Miro]

Thank you very much uHu. Really valuable information.

I very much doubt the diesel specialists who did my injectors knew that either. The troubling thing is that they didn't want to remove the injectors on their own, and that's why I had to use the services of another shop for the removal. So basically, the injector specialists never did have a good look under the hood of the truck nor the VIN. And chances are, they have most probably adjusted the pressures to the early version specs.

I am not too keen about removing the injectors again, considering the fact that they may end up adjusted by the specialists to the same early version specs again. The receipt I got did not contain any technical data at all. I'll try to speak with them and find out what pressures they usually refer to for those injectors. The result is questionable though; those guys keep their wisdom in an eager manner.

At the mileage of my truck, a revision of the IP would not hurt for sure. So if I was to leave the injectors adjusted to (probably) the early version specs, and have the IP refurbish, would this be good idea? Or even refurbished, the injection pump would not be able to keep up to the higher second stage pressure for long?

Yes, the intake pipes with the EGR were cleaned. Unfortunately, not the intake manifold. It has not been removed off the engine block and this is were most of the oily soot was.