Engine noticeably sluggush when warm

[CHe]

Strange problem, when the engine is cold it feels really good, quite alot of punch. But when the engine warms up and gets to operating temp it feels sluggish and I can't figure out why. The engine isn't overheating or anything. It's like the tune on the standard computer changes once it's warmed up or one of the sensors puts the tune out of wack. Also built a cold air box around the air filter and ducted for outside the engine bay as I thought it could have be the intake temp getting up with the engine warming up but same problem after install.

Any ideas would be great.:1zhelp:

oh, and it's a soarer 1uz in a 2wd hilux running the standard ECU.

 

[CHe]

I'm thinking temp sender problems or maybe the air bypass valve. I does idle faster when warm it think.???

I don't want to change to an after market ECU yet. I thought the standard ECU's should be good. Toyota/Lexus would have spent 100s if not 1000s of hours on the tuning.

 

[jibbby]

Tough call...Did you try changing the plugs and wires, and do the whole tune up thing...Sounds electrical in nature...or a bad ECU perhaps..

Did you get a diagnostic check? Check engine light come on?

 

[CHe]

I changed the plugs and the plug leads but the problem is still there.

There's no check engine light.

Any ideas anybody still???

 

[CHe]

More idea's for the problem

I was going over the wiring diagram for the sc400 and notice it has 4 oxygen sensor but I only run the ones in the exhuast manifold, so only 2. Would this cause a problem? Or are the oxygen sensors I have faulty? Also, it idles high a lot of the time but this could be a problem with sticking air bypass valve.

Also the is only a problem through the mid-range (top-end power is still ok) under load and when it's warmed up.

Any ideas anybody?

 

[jibbby]

If your original oxygen sensors are not intact and operating normally this could cause you hesitation, stalls, or sluggishness... You should have all four...Why are two missing? Did you do exhaust mods that eliminated two sensors? However, the check engine light should come on if you had those sensors missing...Tough to call...I just relocated my 02 sensors and my idle is slightly low and even stall every once in a blue moon....

 

[CHe]

I was talking to a guy at my work today who owns a *** import soarer (same model engine that I have in my Hilux) and he said that there are only 2 O2 sensors before the cats and then 2 piros (exhuast temp sensors) after the cats in the japanese sold soarer. It's the US sold SC400 that has the 4 O2 sensors.

Can anybody clear this me?

I thought when I was wiring it up there wasn't the wiring for the extra O2 sensors.

Could not having the exhuast temp sensors cause my problem??

PS, the engine check does not come up when this problem happens.

 

[sideshow]

u dont need 4 o2 sensors
ive done afew without the back o2s and had no probs

i havnt seen soarers with 4 o2 sensors from japan

maybe u can try yr ecu in another car

or you can get a diagnostic plug and wire it up then take it to a good mechanic shop and plug a scanner into it and read the live data of it

the prob yr explaining can be over a million things so tryin to fix it on here might be hard

unplug the coolant sensor and see how it goes

how much sluggish does it go

mine feels good some nights then when its hot it prob feels 5 or 10 % less power

mine also goes better when i have 75 % throttle rather than 100%

by pluggin a scanner into it u can see what the timing is doin

and also maybe fit an air fuel ratio meter

wont be cheap to fix unless u fluke it

did u check for codes it should be first thing u do before u start pullin it apart

anyway good luck i get **** jobs like these sometimes and it can take days

and thousands of dollars hehehehehehe

 

[CHe]

I was talking to a friend who used to work at toyota and he thinks it might be that I was only using 95 octane fuel.

He came to this conclusion because the engine has 2 knock sensors and is probably very sensitive to knocking and the computer is probably retarding the igniton as all fuel in japan is higher octane.

I would test this by using 98 octane fuel but me car is off the road at the mo.

Could this be it????

 

[och]

Its most likely your MAF, they are very prone to failure on these cars.