Lack of power, sluggish... even after a tune up.

[RedPhoenix]

Okay so I have been batteling this issue for the last year...

Basically the car feels alright when its cold, but when it warms up, it loses all its glory and feels like a 5sfe has been shoved under my hood.

I have done the following.

Plugs
Wires
Coils
Caps
Rotors
Injectors
Fuel Filter
Coolant Sensor

Swapped MAFs
Swapped ECUs
Used the downstream location for the O2 sensors


Stock motor, no cats.




My only CEL is upstream O2 sensors... which I have replaced MANY times... and even tried swapping them to the secondary (same 4 wire sensor) in a different location just to see if it would help... and nothing.. still have the code.

Honestly, it feels like its not advancing timing anymore and its stuck at a certain set point.

Any insight would be great.

 

[samsdad]

I'm battling a similar issue but there is one slight difference in the fact that the one I have has a piss weak spark when it decides to have spark but I've traced it to a problem in the engine harness which may also be affecting you...

As you will know on the front of the engine there are two Cam Angle sensors and the Crank angle sensor, These aren't the problem, the wiring that goes down the front of the engine to them is though. Near the front of the L/H cylinder head there's two plugs by the front injectors, these are where the sensors part of the harness plug into remove this part of the harness and untape it (some disassembly of the front of the engine is needed, i.e timing belt,L/H cam gear and backplate neeed to be removed) you'll find due to engine heat the insulation has degraded around some of the sensor cable joins, moisture will have gotten in and a poor or dud connection will have developed as a result, same will be the case where the shielding connects to the earth cable so you will have a poor signal to the ECU. The one I've got kicks then looses spark as this bit of wiring goes "Open circuit" when there's any vibration from either turning it over on the starter or when it tries to fire (depending on which way you hold your mouth).

So when this happens as you've discovered the first sign is it being "Flat as a pan cake" then at worst case it won't even start as the ECU won't be getting Cam nor Crankshaft signals so as far as it's concerned you're just sitting there with the ignition on. In the case of mine I think that it may have been a pre-existing problem in the car that it came out of in Japan as there were signs of a lot of recent work and trouble shooting having been done

 

[Oranges]

I've got a similar problem to the orignial poster.
My 1uz feels like it's got a good extra 20-30 kw when cold, but once it's up to temp it drops off a bit. But I also have a few other issues, that may or may not be related;
It wont idle from dead cold, requires throttle for about 15-20 seconds before it will idle. And then the idle is too low (around 600rpm), keep in mind this is dead cold.
Also starting from dead cold, it sputters and wont start without throttle.

I don't think our problems are the same, but on the off-chance I thought I would post.

 

[sideshow]

hey oranges
check over yr wiring
u need to wire it properly or the idle motor wont reset after each ignition cycle
or your idle motor isnt powered up
or your idle motor is stuck which is common

 

[samsdad]

I'd also check to see if the O2s haven't spat the dummy

 

[sideshow]

wire up the round diag plug and plug a scanner and see live data
it's best way to solve things
as when someone says lack of power I can think of a million reasons

does it miss
does it feel liked blocked intake of exhaust
make sure it's not mechanical
does it go from good power to bad power quickly or does it gradually
loose power
if timing is retarded then it's most prob in limp mode
and only way to see if timing is retarded is on dyno or a
scanner to see what the ecu is trying to do

trying to diagnose someone saying lack of power is like
trying to guess what disease last weeks prostatute has

 

[sideshow]

just remember what makes a good service manager
ask customer a thousand questions as this will make it easier
to maybe figure out what's wrong

 

[sideshow]

I learnt all that working for diahatsu for 7 years hehehe