KZJ78 1KZ TE misfire at higher revs

[tommi786]

Hi all. I recently had a full overhaul done on my 1KZ engine with all genuine parts etc. Had pump serviced as well as new nozzles. Ran a dream for the first 3000 km or so. Good power after running in no smoke and very sweet sounding engine. Still runs wonderfully when driving. But I just noticed today that at a stand still when revving between 2000 to 3000 rpm there is a very strong misfire. None at idle at all. None when driving at all. Does it when engine is cold and hot but a little better when hot. In this rev range, when misfiring there is a fair amount of greyish blue smoke from the exhaust. However when driving even hard uphill etc there is no smoke at all. No smoke on idle either. No knocking sounds or anything else that is unusual.

Am at a loss why it would misfire when revved stand still bit not when under load in normal driving.

I suspect either contaminated fuel, air in fuel lines through a leak although I can see none or then a faulty injector that is not quite spraying correctly when not under load. Before I part with more cash to have this checked, any thoughts?

No error codes neither is ECU suspect as I have swapped it with a Surf one just to test and I know surf one is good.

Thanks.

 

[StarCruiser]

Is it losing any water?
Also, check your oil level isn't too high.

 

[StarCruiser]

When you say 'full overhaul' what did this include and why was it performed?

 

[tommi786]

Thanks for the reply. It's not loosing water and engine oil is at correct level. Engine had done 230K and had low compression hence overhaul. Full overhaul was a complete rebuild with new rings bearings valves guides etc. It was professionally done using only genuine toyota parts.

 

[StarCruiser]

Any warranty from your professional rebuilders?

 

[Shayne]

Why are you revving at 2000 to 3000 at a standstill ? we all turn the fuel up for a bit more power but i can imagine that high a rev at a standstill for any length of time causing a poor afr .

 

[tommi786]

No official warranty but they are very good and have offered to check it without charge but i am generally hesitant to have mechanics fix what perhaps is not broken......

I don't rev the engine normally. Only by chance did I do this after it was a little hesitant on idle when i first started it this morning.

 

[StarCruiser]

My thoughts are to look at the possibility of oil build up coming from the turbo when it spools up but that's just my gut telling me.

Shayne's got far more experience with this engine than I will ever have.

My only advice would be to check everything that has been done especially wiring and for damp in any of the plugs that may have been removed. Check they are mated correctly and that their seals have not become dislodged by poor fitting. If it starts on the key without having to lift the bonnet and operate the primer then you don't have any fuel leaks and air bubbles will soon clear and won't cause smoke so personally I think that can be ruled out.

 

[Shayne]

I messed around a lot with my 90 series 1kz-te and getting the fueling right was a pita . First thing i would try is turning the fuel down to see if it cured the problem , if it did i would turn the fuel back up again and fit a k&n air filter to help the engine burn the extra fuel .

 

[tommi786]

Thanks Starcruiser and Shayne. Possibly a stupid question - how do I turn the fuel down?

Also on the subject of Damp, I did have the engine hosed down last week with water (not high pressure) to clean up dust from a trip. Could there still be damp lurking around about 350Km driving later that I ought to clear up with a commercial water displacement spray from the connectors?

 

[Shayne]

There's a little cap on top of the fuel pump pull it off with pliers and there is a little screw held with a 10mm locking nut turn it anti-clockwise just a little . Be sure to make note of where it was so you can put it back as it was later . I clean my engine with a pressure washer and its never caused a problem .

 

[StarCruiser]

It all depends if the connectors are mated correctly and have fully intact seals. Well worth a check I would say whatever you do. We are looking for something that's changed and the hosing down may have got water where it shouldn't because of a connector that hasn't sealed correctly. I've seen connectors on other cars with torn seals through mishandling or whatever. If you have something like that, combined with the hosing could be the answer. Not by any means certain but time to get the detective hat on and the spy glass out. [emoji4]

 

[Beau]

In my opinion I wouldn't touch the fuel adjustments unless you've actually messed with it before. The blueish smoke would indicate oil being burned. Seeing as you didn't overhaul the turbo, is it possible the turbos blowing some oil into the intake and choking it a little?

 

[Shayne]

Would you not be seeing smoke on boost all the time if the turbo had blown a seal ?

Colour of smoke could be deceiving at those revs could it not ?

 

[Beau]

At standstill when free-revving the engine there is less fuel being injected, say at 3000RPM to when you're driving actually doing 3000RPM. So when driving the additional fuel could potentially mask any oil entering the engine, hence why it drives fine and theres no traces of smoke. That's just my theory anyway... The problem all together does sound rather strange...

 

[tommi786]

Update from early this morning - car started as usual on first spin of the key. Slightly rough running immediately after startup with slight smoke which disappeared shortly after. Still missing when revving and smoke following the misfire pattern. The smoke is dark greyish with tint of blue but does not have the strong oil burning odour common with engines that are burning oil.

I want to eliminate contaminated fuel first as I only refilled the car a couple of days ago and that could be the problem. I live in Kenya and it is not unusual to hear of cases where fuel is contaminated with kerosene/other stuff. As I have half a tank of diesel, is there an easier way to check whether this is a problem rather than drain and refill? Am thinking a separate supply from fuel can using a pipe straight into the inlet of the fuel primer pump. I will drain out the filter first for old fuel. Any issues in doing this? As my problem is while standstill, suspect this is relatively safe and easy to do compared to vehicle in motion.

Next attempt would be checking all wiring for water/vapour.

Turbo could be an issue but it would in my mind smoke even more under load? I did not refurb the turbo but replaced it with a second hand unit from a low mileage engine. My old one was blowing a lot of oil and had a fair amount of freeplay. Replacement unit when physically inspected looked in good order. However, as is the risk with replacement parts that are not new, this could be a further area of investigation....

Could it also be a defective injector nozzle that is perhaps not giving enough fuel or alternatively too much fuel when the engine is not under load and revved? All for nozzle tips were replaced with genuine new ones at the rebuild.

 

[StarCruiser]

Contaminated fuel could be the issue. Your suggestion of running it from a fuel can is the way to go. Just make sure your fuel can has good diesel in it. You should be able to push the good fuel through with the primer. Try emptying your fuel filter using the drain at the bottom and see what comes out. Catch it in a glass jar or the like, look at it and smell it. Once you get the good fuel primed you will need to run it for a while as the fuel pump contains quite a bit of fuel.

Your turbo and everything else is probably fine in that case. I would have expected a duff injector to show up as smoke probably straight away.

Let us know how you get on.

 

[tommi786]

Tried the fuel swap using good diesel from a can. No change even after running engine for 30 mins. Guess fuel not the issue. Wiring also seems to be all ok.

I have however noted a couple of things - injector one looks a little damp on the outside including the head right around it. No pooling - just a light diesel mist - could that be the issue?

Also checked that the EGR vacuum valve was still closed and not stuck open (vacuum lines were disconnected at rebuild). It was closed properly but i did notice some engine oil around the valve. Am thinking that I may indeed have a turbo oil leak issue..... but why would that cause a misfire?

 

[Shayne]

My thinking is the turbo should be redundant while your not moving but when you rev that hard it will boost up , the sensors that tell the pump to chuck more fuel in on boost are on the intake so if you are running slightly rich (which will feel good while on the go) you might be running very rich whilst boosting at a standstill .

Could be wrong of course something in my grey matter is saying there is a speed sensor somewhere which might prevent this but i can't locate where that thought is coming from ?

The damp injector would have me return to the rebuild shop anyway .

 

[Beau]

That damp injector sounds like it could be a issue. Maybe that injector isn't holding pressure, or maybe the injector is slightly blocked? This could give a misfire like you describe? Does the truck fire up instantly with the turn of the key or does it require a couple cranks?