1uzfe still a mystery

[tetnt07]

I have a 1992 sc400, we installed a 1uzfe from a 1992 ls400, using the wiring harness and ecu from the ls400. after extensive rewiring of the harness and chasis, it runs and everything seems to function. the problem is that when i first start the car cold it run fine but as soon as the car warms up it chugs when its under load (moderate acceleration/uphill)
ive changed the dist. caps,wires,plugs. checked oxy. sensors fuel pres.
TPS, MAS. what am i missing?

 

[Peewee]

Can I ask why you using the LS400 harness and ecu?

Wouldn't that have just caused masses of headaches?

Why didn't you use the SC400 loom/ecu on the LS400 motor?

 

[tetnt07]

all burned up

the original "sc" harness and ecu were damaged in a fire.

 

[Peewee]

Surely it would have been easier to get an SC loom though ?(although, I bet hindsight is a good thing).

I've played with box looms and the engine side is the only thing that is similar. The rest couldn't be more different in not only the plugs, but the orientation of every wire.

Have you had the injectors cleaned?
Did you test drive the LS motor before putting it in ?

 

[sc-driver]

seems like your ls400 ecu might be going bad.

 

[-Nemesis-]

Could be a mass air flow sensor problem too. Try unplugging it when it's playing up and see what happens when you drive.

I did this on mine when it was undriveable all of a sudden one day. Soon as I unplugged the MAF it went great so I knew that was the problem.

 

[sc-driver]

Here, read my thread on clublexus:

http://www.clublexus.com/forums/per...oblem-white-smoke-running-extremely-rich.html

Turned out to be the ecu. The quick acceleration on cold start ups, and then sluggish acceleration when warm, that sounds like an ecu related problem. IF theres white smoke that comes out and it smells like FUEL, then it is most definitely your ecu.

Good Luck!

 

[**Anyhow]

same issues here!!!

just got back from a 3000km round trip and had to deal with mine bucking like a mule whenever i put my foot down to pass, or any uphill slopes. My idle seems to be all over the place now too and the occasional big puff of white smoke when i start it up.

i have had it to the workshops, who acknowledge there is a problem, but none of their diagnostic equipment has been able to find it. so they have put it down to being something electrical...???
they said that because the problem is so "minor" their equipment cant find it. on the freeway there is nothing "minor" about it...:angryfire:

i should add that not only the shops in house equipment was used, but also a private guy they use as well.

is this what you have been experiencing???

have you a fix for it???

has anyone had the same problems???

 

[rivmasta]

Im not an expert, but Ive had similar symptoms in a couple of engines. One turned out to be a blocked fuel filter, does the stock ECU monitor fuel pressure? The other was a cam gear out by a tooth.

 

[**Anyhow]

the fuel filter is almost new and there are no error codes so the cam timing should be fine...

problem only occurs around and above 3000 rpm and when under load. cruising above highway speed has no problems but a soon as you hit a bit of a hill the :censored: start.

also the idle is a bit messy and will ocassionally stall

 

[rivmasta]

youll need wiser heads than mine to answer your questions then...

 

[Peewee]

Have you had the injectors cleaned?
Have you had the fuel pressure measured at those RPM's?
Are the spark plugs gapped correctly?

 

[**Anyhow]

injectors and fuel pressure not yet. hopefully going to sort that out today.
all plugs are new and leads have been tested ok

 

[svpmx83]

the sc400 runs the PWM fuel pump ecu and as far as I know the LS400 is two stage resistive.

so with the ls400 ecu and engine wiring - the sc400 fuel pump will always be running in low speed mode - the cold start injector is probably masking the lean out condition until the engine warms up

 

[**Anyhow]

did i mention that the engine is in a 4Runner... sorry.

as far as i know the fuel pump is the 4Runners and the tail pipe is always black. doesnt that mean that if anything it is running a little rich?

 

[svpmx83]

my answer was for the original poster

 

[Peewee]

the sc400 runs the PWM fuel pump ecu and as far as I know the LS400 is two stage resistive.

so with the ls400 ecu and engine wiring - the sc400 fuel pump will always be running in low speed mode - the cold start injector is probably masking the lean out condition until the engine warms up

The CSI only runs when the key is on START, as soon as you let go the CSI stops.

But the point about the fuel pump is valid. I'm not sure what voltage the pump defaults to, chances are without the SC400 ecu in there it won't run at all, and as such I'd hazard a guess its been wired independently. Just a guess though.

 

[sideshow]

hey anyhow tow it down to sydney and ill fix it for ya
or pay me to fly up and fix it
has yr car ever run right on this 3000km trip
problem with 99% of people out there with electronics is they have this diag scanner worth 7g but dont know what to look for in the live data
and when there is no codes they are fukt
first thing to check is for codes
have u connected the check engine light
if not do the people who worked on it know hopw to do all that
if there is no codes then get a multimeter out and start testing

reason they said its something minor is so it looks like they actually did something and got somewhere heheheheh

but if u dont try get codes to maybe get an idea if somethign is wrong then u might be running round in cicles
so check codes
drive it and test fuel press
like everyone else says unplug air flow meter and see if it cures prob

 

[**Anyhow]

Thanks sideshow...:censored:

that trip WAS to sydney...:censored:

another full set of plugs, which were replaced not 3000k ago...
new leads, which were supposedly tested and all ok at the same time...
an injector clean and fuel system check...

and everything seems to a ok

 

[sc-driver]

dude, if you have white smoke on cold start ups, then its your ECU. Thats all I can tell you.

Trust me, mine had a TON of white smoke on cold start ups. My low end torque was really shtty too. I replaced the ecu and BAM!! no more white smoke and my car actually has balls down low.