1kz-te oscillating power (1 Viewer)

[Francis A]

Need help with my 1kz-te 78. Whenever i floor it, the engine's power oscillates. It wont reach above 3000rpm. Had it dynoed and only had 56rwhp and 280nm of torque.
Had the injection pump serviced thinkjng that it would fix the issue but it hasnt. New injector nozzles also.

We lifted it through the rear axel and made the engine run. Speedometer read 140kph and reached near to 4000rpm but when running on the ground the power would oscillate.

It has no problem starting. Starts everytime on first click. A bit of smoke on start up.

Coolant level is not decreasing.
No blow-by
Egt post turbo max 425c
No engine codes
O/d not blinking
Ecu is good
Tried a different ecu same problem
Fuel consumption currently at 12l/100kms
Map sensor is working

33 x 16 tires
4.88 gear ratios
Full aluminum radiator
Manual boost currently at 13psi
3 inch exhaust from the turbo
Cleaned the fuel tank due to clogged strainer
New fuel filter
Fitted an Oil catch can
Clean air filter
New atf fluid

I really couldnt figure whats wrong with it. Could it be the throttle position sensor? Speed sensor? Worn transfer case? Clogged fuel lines??

Any input would be greatly appreciated. Thanks

 

[GTSSportCoupe]

You've done most of the things I could think of.

One possibility is you're hitting the ECU fuel cut. It starts to happen around 14psi and will cut the power in the way you describe. Where are you measuring boost? Maybe the ECU boost sensor is seeing more boost than what you see on the gauge?

I use a special adjustable bleed valve to reduce the boost that the computer sees. This allows me to boost higher before fuel cut (I boost to 19psi). I also turned up the spill control valve screw to make sure the engine still gets enough fuel. Mine is the 2LTE, but it's the same fuel system as the 1KZTE.

Your torque value sounds good. I think you're not getting the peak power because the ECU is hitting fuel cut. Also, landcruisers dyno pretty low because the drive train loses a lot of power (seems to loose about 50hp between the engine and wheels).

 

[Francis A]

I tried adjusting the boost cut 2 psi lower but same symptoms. . Does the check light turn on during boost cut?

 

[GTSSportCoupe]

I tried adjusting the boost cut 2 psi lower but same symptoms. . Does the check light turn on during boost cut?

I've found that the computer starts pulling fuel before the check light. But once the boost is much to high, then the check engine light comes on. Sounds like it's not your problem unfortunately. If I think of any more ideas I'll let you know.

 

[roscoFJ73]

Im surprised that a shop that is good enough to bench test a fuel injection pump can not understand your problem. Im thinking there is still a problem with the pump. How many klms has it done?

Has anyone checked the fuel pick up for blockages?

 

[Francis A]

Im surprised that a shop that is good enough to bench test a fuel injection pump can not understand your problem. Im thinking there is still a problem with the pump. How many klms has it done?

Has anyone checked the fuel pick up for blockages?

where is the fuel pick up at? my fuel strainer was previously clogged. had to replace the whole strainer. could it be possible that the lines got clogged as well? the things is, the symptoms appear only during wide open throttle or close to it.

 

[Francis A]

i havent checked the TPS yet though. could it be the culprit? i was scouring the web regarding 1kz-te fueling and the TPS among others, somewhat dictates the amount of fuel to be injected depending on the pedal position or rather the butterfly? im not sure though. i still dont have a multi-meter to check it.

i downloaded the 1kz-te manual for the surf and upon reading, the tps should have a reading of 1.4ohms to 9.5ohms from the vta & e2 terminal and 2.5 to 5.9ohms from vc and e2 terminal when the throttle valve is fully open. should the reading between the said value or should it be on the maximum value during wide open throttle

 

[Francis A]

I've found that the computer starts pulling fuel before the check light. But once the boost is much to high, then the check engine light comes on. Sounds like it's not your problem unfortunately. If I think of any more ideas I'll let you know.

hey i just got home from a long trip and had the chance to test my rig on the highway. i tried to floor it and suddenly the check engine came on and had to back off the throttle. after backing off the check light went out without even turning off the engine? it was the first time that the light came on while flooring it. it got me worried a bit because im not sure if it was due to the boost cut or something else

 

[GTSSportCoupe]

hey i just got home from a long trip and had the chance to test my rig on the highway. i tried to floor it and suddenly the check engine came on and had to back off the throttle. after backing off the check light went out without even turning off the engine? it was the first time that the light came on while flooring it. it got me worried a bit because im not sure if it was due to the boost cut or something else

That is very typical of the fuel cut. I think you might be running more boost than you think you are. Try turning the boost down even more and see what happens. Also, pull your ECU codes again. Now that the light came on, there will be a stored code.

 

[Francis A]

yup. will check the codes and post an update as to what error caused.

anyway, how is the a2w intercooler going? did it give a noticeable power increase?

 

[GTSSportCoupe]

yup. will check the codes and post an update as to what error caused.

anyway, how is the a2w intercooler going? did it give a noticeable power increase?

Love my Air/Water intercooler. Totally transformed the engine. It lowered the EGT's so much I was able to add a lot more fuel and boost. Way more power now. The 2LTE has very little power to start with, and adding the extra power made it like a different engine.

 

[Francis A]

Love my Air/Water intercooler. Totally transformed the engine. It lowered the EGT's so much I was able to add a lot more fuel and boost. Way more power now. The 2LTE has very little power to start with, and adding the extra power made it like a different engine.

after i sort the issue with my engine, im planning to put one on it. ive been thinking about a2a but i dont have enough space under the bonnet to mount it. the a2w seems easier to install i think than a front mount because the hoses are easier to route than the piping for a2a..

say i install an a2w intercooler without fiddling with the spill valve, will i gain more torque off of it? or just lower egts?

 

[GTSSportCoupe]

after i sort the issue with my engine, im planning to put one on it. ive been thinking about a2a but i dont have enough space under the bonnet to mount it. the a2w seems easier to install i think than a front mount because the hoses are easier to route than the piping for a2a..

say i install an a2w intercooler without fiddling with the spill valve, will i gain more torque off of it? or just lower egts?

If you just add the intercooler without doing anything else, you will lower the EGTs by a huge amount. The engine will run cooler. It will run more efficiently because of leaner AFR (dense cool air = more oxygen). You will probably gain a little bit of power because of the more complete combustion. It will be easier on the cylinder head (pre-cups) too, lessening the chance of cracking it in the future. You won't have to back off on the throttle to control high EGT's.

 

[Francis A]

cool. what numbers do your rig now have after the a2w?

 

[GTSSportCoupe]

cool. what numbers do your rig now have after the a2w?

I've not put it onto a real dyno. Using 'PerfExpert' app, I get 100whp. It does a 1/4 mile in 20.5s@110km/h. 0-100km/h in 16s. Mine is Automatic.

Not 'fast', but MUCH MUCH faster than it was, haha! Stock, the LJ78 puts down about 45whp!

The 1KZTE can make way more power. The 1KZE has a 12mm injection pump, the 2LTE only has a 10mm injection pump. My fuel is maxed out right now.

 

[Francis A]

if i only saw your post earlier i would kept my 2lte haha. . currently my 1kz is gutless which urges me to swap it with a 1hdt engine if i could save enough money but the conversion process is hard and i dont want to lose my a/c nor mount it under the body. however, if i can sort my current engine problem and start tuning it for more power ill probably keep it

 

[GTSSportCoupe]

if i only saw your post earlier i would kept my 2lte haha. . currently my 1kz is gutless which urges me to swap it with a 1hdt engine if i could save enough money but the conversion process is hard and i dont want to lose my a/c nor mount it under the body. however, if i can sort my current engine problem and start tuning it for more power ill probably keep it

The 1KZ can make a ton of power. With tuning they make 200hp at the engine (150whp).

That said, the 1HDT will be more efficient and run cooler making the same hp.

 

[roscoFJ73]

where is the fuel pick up at? my fuel strainer was previously clogged. had to replace the whole strainer. could it be possible that the lines got clogged as well? the things is, the symptoms appear only during wide open throttle or close to it.

Most landcruisers have one in the fuel pick up in the tank. Its like an inline filter inside a gauze bag. I heard of some vehicles where at high speeds the gunk in the tank covers the gauze and semi strangles the fuel supply. But at low speeds there is ample fuel getting through.
I doubt your lines would be blocked. Blockages are always around the fuel pick up, fuel filters or the mesh bit on the fuel inlet at the pump.