1kz te bad low end torque

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May 6, 2008
Dear all,
I have a 1kz-te in my CJ-7 and wanted to ask on this forum as it seems to be quite active with toyota diesels.

Here is my problem, and apparently other folks have it too. I have BAD low end torque (under 1800RPM). After 2000Rpm my car is a rocket (albeit a heavy one). By bad I mean it just wont respond under 2000RPM even if I floor the gas pedal. Now I have checked and changed many things and nothing seems to make a difference.

Searching online and other forums I have found out that apparently many landcruiser guys with the 1KZ-TE complain of the same thing. for example check here:

http://www.lcool.org/technical/elec_die … uning.html

and here:

http://www.lcool.org/technical/90_serie … specs.html

Apparently low end fuel is kept quite low to avoid emission problems!!! That kind of sucks for me

This happens with different exhaust, different air filters and different engines and pumps!
In the course of my swap I have changed my pump 6 times, changed engines twice, redone the exhaust and changed the air filter but the bad low end torque/power issue remains.

The exhaust noticeably 'sputters' under 1800 rpm, and gets nice and smooth after that- wakes right back up after 2000RPM

Thinking it might have been my EGR- plugged the EGR tube. The EGR valve was definitely stuck. The engine seems smoother and I would say roughly 10-15% more powerful but the bad low end torque is still there.

Also, I checked my turbo boost yesterday. I only seem to get boost past 2000-2500rpm, thats where my car seems powerful. I have also noticed that if I rev it up (so to get the turbo going) kick it into next gear it feels a LOT more powerful even if the revs drop below 2000rpm. From my sports car days this seems like turbo lag, only I am experiencing a LOT of it.

I have ZERO boost (no turbo pressure) under 2000-2500 rpm. My turbo boost only starts past it and goes to 14-15psi at WOT.

Correct me if I am wrong but in these turbo deisels isnt the turbo supposed to kick in QUITE early? say around 1200-1500rpm? Even in my Z I would start getting boost around 3000rpm (and it redlined at 7500). So from 3500-7500rpm I had full boost.

Signs of a bad turbo? but its not leaking oil or anything. Is there a adjustment somewhere to get boost on earlier?

Btw searching around I also found this article (which i mentioned earlier):

http://www.lcool.org/technical/elec_die … uning.html

It states that :
"Due to strict European emission requirements that do not apply here in Australia, Toyota purposely limits the amount of fuel at low engine RPM. This results in an engine that feels sluggish at low RPM but gets up and goes when the engine revs beyond 1800 - 2000 RPM. All owners of Prado 1KZ-TE and Land Cruiser 1HD-FTE will have experienced this and most probably mistaken it for turbo lag (which it isn't - more correctly it is fuel lag)."

Im confused- Is what I am experiencing normal? that really sucks!
What year is your engine and what is it originally out of?

I've spent some time driving one in a 2003 hilux, the turbo starts to whistle around 1500rpm, it doesn't have a boost gauge though.

I'd remove the turbo and take a close look. Specifically at the exhaust housing (cracks), exhaust wheel (damaged blades) and wastegate flap to see if it is not closing properly.
Sounds like it maybe normal after 6 pumps and 2 engine swaps. I would get it dynoed to ascertain the exact HP and torque figures.
It is only a 3 litre diesel
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Here you can clear ear the turbo sound in Prados with 1KZ-TE @ 1200 rpm ... how much boost not sure but sure they are archiving boost ..

Anycase turn up your fuel .. :D ( get a Pyro )

Which gears and tires are you running ..?

Which tranny ..?
Its originally out of a 96-97 Hilux Surf, So is the Tranny and the differential. (my car is basically a Hilux Surf :) )

I Have a 2.5" exhaust (no silencers) - straight pipe from the exhaust all the way out so I can hear the turbo start whistling at 1000 rpm but there is NO boost (I have checked this by attaching a pressure guage to the manifold). I only start getting boost past 2000-2500rpm (2-4 psi) and it goes all the way to 14psi at WOT.

So the bad low end torque is only my problem?

Could someone tell me the part number of the ECU they are using? apparently there are multiple ECUs that can work with this engine- might be my ECU is bad or the wrong one.

Is it possible for the turbo to become 'restrictive'? I can imagine a propellor thats hard to turn may require more spool time and more air/exhaust pressure than normal to turn up.

I had a 1KZ put initially (that had compression problems so I returned it and got this one) however that engine behaved exactly the same way. At that time I thought it was a compression issue, but apparently its not so (this engine has perfect compression)
When you swapped from the 1KZ to the 1KZ-TE, did you keep or change the turbo?

The turbo on those is fixed geometry, so that can't be affected by the ECU, but fuelling levels can.
I'd be looking for air flow or air pressure sensor issues if the same problem has repeated itself with two different engines and turbos.
The earlier engine was also a 1KZ-TE ( returned it as it had bad compression).

With the new engine I got a new turbo, but both engines behaved the same way!!

I guess its possibly not the turbo. The turbo pressure sensor works perfectly (tested it myself) and meets factory specs.
btw- whats a pyro? :)

It is a pyrometer. At gauge that tells you your exhaust temperature. Keeps you from, or at least tells you when, are running the rig too hot....ie...melting things...
If you are running a complete factory engine ( Factory settings ) .. you didn't asnwer ( or I don't see ) which tires and gears are you running ..

Prados with 1KZ-T with factory tires 265 ? and factory gears 4.10 ? are a real rocket with this engine ..

Its looks weird to me .. coz newer engines are boosting more sooner pressure on the intake manifold ..

My best bet in your case should be a diesel issue ..
Another thing about the 1KZTE is that it has about 50 sensors on the engine. If they are not dealt with,it maybe part of the problem.
Sorry to dredge this back up, but it sounds very much like a problem I am having with the same engine. Did you ever get this sorted?

I am pursuing the problem possibly being the throttle position sensor, and will be checking if it is mis-wired. When you swapped engines, did you also swap harnesses?
The problem was a bad ECU. Changing the ECU fixed the problem. My harness was custom made as back at that time I was unable to procure complete harnesses.

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