LS400/Celsior sluggish

**Mr DOHC** · 27-09-2012, 09:52 AM

Hi

my mate has a UCF10R LS400 that has been sluggish for quite a while. The power comes and goes, somedays it good and others its not.
To me it sounds liek the computer is playing games, ie. retarding the ignition etc.
he has replaced the plugs with platinums or iridiums, could this be an issue?

is there a common issue with these motors?

Phil

**roadkill** · 28-09-2012, 10:28 AM

hI,

what year model is it? I've found these engines to generally be really good but can have all sorts of random things fail on them. Mine has a dud temp sender which effects how easily it starts (air fuel ratio) You can buy 89-92 ecu's pretty cheap through yahoo japan or even here in aus. Maybe try swapping it and go from there. Have you run a diagnostic check? Might be throwing a code but no CEL? My LS400 throws a TPS error, but no CEL.........

bEn

**Z2TT** · 28-09-2012, 04:46 PM

Is the TRC Light on?
If Yes check Error Code

Can be limiting power when there is problem with Nitrogen Accumulator low on Gas.

**Kedderz** · 28-09-2012, 04:58 PM

Replace the coolant temp sensors, I had the same problem in my uzz32, replaced them and it was good power all the time.

**CrUZida** · 30-09-2012, 03:03 PM

Could be one of the coils or ignitors dying.
Very common, and a lot of people don't realise that its dropping down to 4 cylinders...

**Mr DOHC** · 30-09-2012, 03:06 PM

Originally Posted by CrUZida

Could be one of the coils or ignitors dying.
Very common, and a lot of people don't realise that its dropping down to 4 cylinders...

What's an easy way to diagnose?

**CrUZida** · 30-09-2012, 07:32 PM

When its sluggish, unplug one of the ignitors.
If it stalls, its the other ignitor/coil
If it doesn't change, its that ignitor/coil
If it gets worse, your problem is not the coil or the ignitor.