The Toyota Landcruiser Owners Club

[Beekeeper]

Hi All,

I'm hoping the answer to this question is straightforward.  I can't get my Techstream to work yet as I can't get a driver for the cable that works.  Techstream itself is on the laptop, just the cable driver to sort, hopefully some more searching will turn something up.  Mean time I have an issue which occurs in specific conditions but makes the vehicle almost unusable nonetheless.  The LC drives very well, no smoke, has passed the MOT, and replacing the red and green suction control valves has improved the starting.  It was a bit of a job as I think the red valve supplied was faulty but a Denso pair seem to work fine.  While doing this I had the fault codes read at work which showed showing P1226 Fuel Line Malfunction.  This could have been the SCV, but research also indicates the throttle position sensor as a potential cause.  The LC is a 2004 KD engine.

I've narrowed the problem down as follows:  The engine goes into limp mode when left idling, or on a closed throttle when moving, after a period.  Previously when working correctly after starting the LC it would idle for a short time then the engine note would became louder as something opened.  I'm 99% sure this was induction noise heard as the throttle body butterfly opened further as the engine warmed.  Now there is no change in sound and the engine MIL light comes on after 40 seconds.  So it seems to me that either whatever made the throttle open is no longer sending the signal, or if it is the throttle body is no longer opening as it should.  By observation I can see that the throttle is fully closed with the ignition on but engine not started, and moved to part open once the engine is running.  I unintentionally forced it fully open and the induction sound was exactly as when working correctly.  I've had one session to try to remedy the fault and have cleaned out the throttle body and EGR valve as well as checking all of the vacuum hoses and electrical connections including the two around the turbo.  I would have removed the cover plate on the throttle body mechanism but as the screws were unmovable I thought better of it, particularly given the amount of oil and soot I had removed already which I expected to be the cause.  I've also cleaned the MAF and MAP sensors as well as checking a couple of the filters in the vacuum lines.

I don't mind replacing the throttle body of that is definitely the cause, however the one I have looks different to the aftermarket suppliers' websites (mine has the cylindrical EGR cooler and a right angle bend built into the throttle body as well as a six pin connector) and a Toyota item will likely be expensive particularly if it's not the item at fault.  If it could be the throttle position sensor then I can remove the throttle body and work harder on the cover plate to access and clean it out.  The gears inside feel fine with no free play at the butterfly when being cleaned off the car.

So all suggestions welcome.  I'm hoping that someone will know what triggers the correct sequence of throttle movements after starting and that will point to the cause.

Thanks in advance

Paul

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