Another no power thread

[Albannach]

Hi all, I'm running out of ideas on this, so thought I'd ask for some advice.

I have a 1UZ (from a 1990 LS400) in a Hilux Surf.

The engine starts, revs and idles perfectly when stationary, but when I give it some throttle on the road, it coughs and splutters its way to around 50mph max.

I have renewed most of the engine sensors, the coils, caps, rotor arms, leads and plugs. There are no ECU codes. So far, nothing has helped.

Now, I'm swaying toward the igniters, but don't want to waste money on them if I don't need to. The only thing I could think of, by way of a test, was to unplug them (individually) to see what happened. When each was unplugged, the engine cut out completely. Does this suggest that both igniters are faulty, or does it point to another problem elsewhere?

Any help would be appreciated.

Andy

 

[Albannach]

Apologies, I just noticed that was my first post and I hadn't introduced myself properly.

I'm Andy, from central Scotland, I have had Surfs for a few years and I'm reasonably active on the UK Surf forums. I'm a mechanic by trade; but haven't worked as one, professionally, for 30 years (there's more money in Oil)! To me, auto electrics are fine, but electronics are an alien thing...

I bought this 1UZ-Surf project as a non-runner in March of this year. Thus far, I've managed to get it running and road legal, but I can't seem to get it running properly.

 

[Bushwhacker]

Hi Andy,
Is the TPS new?

 

[Albannach]

Hi Andy,
Is the TPS new?

Evenin' Vince.

It doesn't look new, but I'm sure Graham said it was? I have a spare, used, one in my unit, I'll stick it in when I get a chance. I'm going to run IV for a couple of days, just in case it's a dampness thing.

I was going to drop you a note on HLS, I'll not bother now

 

[Albannach]

Tried two different TPS', the fault is still the same.

Idles and revs perfectly until it gets some load, then it all but dies.

 

[gloverman]

Have you checked your fuel flow? One easy "DIY" way is to remove the return line and put into a measured container. Start the engine and run for a timed period. Work out litres per hour. 60-80 will generally cruise ok but lack power at higher revs. Often at 60l/h and under they often struggle to rev when cold. I like to aim for at least 120 litres/hour.
I would also recommend wiring in a diagnostic plug and checking the live data. This is the easiest way of checking AFM's , temp sensors , TPS etc.

 

[Albannach]

Thanks for the help chaps.

I've tried a few things, fuel flow is good, swapped a few things over, but couldn't get anything to work. I eventually disconnected the STA wire and the truck now runs much better, but is still way down on power. I'll reconnect the STA wire and unplug the Cold Start Injector tomorrow, see how that goes.

The IAC doesn't work either, it gets driven closed if I open it manually, but won't open at shut down. Any ideas?

Over the weekend I'm going to check all the ECU input/outputs, are there any in particular that I should be paying special attention to?

 

[Albannach]

I would also recommend wiring in a diagnostic plug and checking the live data. This is the easiest way of checking AFM's , temp sensors , TPS etc.

I'll see if I can pick one up at our local breaker's yard, I'm going there tomorow for some relays.

 

[gloverman]

My standard test is unplug the IAC. turn key on , check power at centre pins. Start engine and manually hold revs up for about 15-20 seconds then turn off. Does the power turn straight off?? or stay on for a few seconds? Is it an auto or a manual?? Cheers

 

[Albannach]

My standard test is unplug the IAC. turn key on , check power at centre pins. Start engine and manually hold revs up for about 15-20 seconds then turn off. Does the power turn straight off?? or stay on for a few seconds? Is it an auto or a manual?? Cheers

Hi Kelvin. I did your test - There is +12v at each of the centre pins; when I turned the engine off, it stopped immediately; it's an automatic.

I've also noticed that the STA wire has +9-10v when the engine is running as well as cranking, is that right?

Thanks

 

[gloverman]

Back to the wiring. It is not wired correctly. This is why you have no power and the stepper is not working correctly.

 

[cruising]

U did replace a lot of stuff
Why not replace the ecu and maf too

 

[Albannach]

U did replace a lot of stuff
Why not replace the ecu and maf too

Can't be guaranteed I'd not be getting a good ECU and I can't find a new MAF at the moment.

That said, at the moment, I don't think it's either of those.

 

[gloverman]

No point replacing anything until its wired correctly.

 

[cruising]

U change ecu
Fix your problem yes

 

[Albannach]

No point replacing anything until its wired correctly.

U change ecu
Fix your problem yes

As Kelvin said, I need to double-check all the wiring first. If that doesn't fix the issues, I'll get my ECU checked.

Checking the wiring is free