MUDGUTS

****UPDATE**** The problem is now resolved and I can confirm the car performs as it should do, right through the range, transmission operating correctly, etc. Today the technicians at Thor Racing, Coventry, had a look at the fuel pressure and confirmed it was low, so had a look in the tank at the pump with the intention of replacing this, they also had a look at the fuel filter (which was clear) and after a good look around, discovered a fuel clamp, hidden away on the fuel pipe by the differential. Once removed, the fuel pressure was confirmed at correct, the car road tested and as I say above, it is 100% now. Thanks to everyone who contributed to this thread, as SRK said the fuel pressure should be looked at. I think the voltage rise to the pump had been checked when the car last went in but we ran out of time to persue this any further and I have been living with it since I bought the car. The increased noise from the pump recently is still a mystery but the pump is now silent. Somewhere a mechanic is missing a fuel clamp...

Hello landar, Apparently OBD2 came in earlier in the USA than Europe, we got it later. I definately have OBD 1 though, sadly. What I have said before still stands, if I put the tranny in Neutral and floor it the engine will limit to 4000 RPM but by 'blipping' I can get the RPM up and I have had it higher whilst driving, so it doesn't seem to be a hard limit.The more I think about it, the more this problem occurs when extra fuel is demanded. Some time back I updated the thread on the UK forum with this: I'm dropping the car off for the pump to be replaced later, so should have the car back by the weekend. If the problem is still there, I know it's not that.

This is a good suggestion but I don't have a guage otherwise I would do this. The issue I have is that whilst a good car, I just cannot justify any more expense unless it cures an existing fault and is not too much to fix. Anyway, this evening the whine is not only still there but seems slightly louder, so I conducted a bit of research: The noise ocurs just after start and definately when I floor the throttle, it will stay on, whining away, until I take my foot off the pedal. At the same time the engine will hold back as always, so the noise and the engine holding back are happening at the same time. Also I tested the system that ups the pump voltage again by jumping FP and +B in the diagnostic port and the pump does seem to get louder, it's not so pronounced if the engine is off but with the engine running, the noise I hear is the same as described above, so now I can be fairly sure that the whining is from the pump working harder. My theory now is that the pump was never powerful enough to supply the extra fuel demanded and that leads to the engine holding back somehow. I'm going to get a new pump tomorrow and have it fitted as soon as possible. I'll try to keep the old one to carry out an autopsy on it and will post up the results.

Sadly, mine is only OBD 1 (have double checked) and you are right, if the car was fitted with OBD 2 this would have probably have been diagnosed by now. With regard to the octane booster, this is something I thought about but never did, again due to trying to limit the expenditure. I could have had the knock sensors replaced but that would be more cost and they haven't produced a fault code. I checked today using the 'Flash' method in the OBD 1 socket and nothing comes up, in fact the only fault codes this car ever produced were for Oxy sensors, which were replaced. I could send it to the specialist one last time if the pump does look like failing and have that done, as the car is otherwise a good runner and has a valid MOT test until September, once there I could allocate another £100 to get it on the dyno there and let them mess around. Apparently it may be possible to see if the ignition is being affected when this glitch occurs: That would point to the knock sensors.

Thanks for the input Landar, I'm pretty sure it's not the above. One of the things the specialist did was to swap those components for known servicable ones and the fault was still there. It is definately related to demand, so if I allow the speed to build up it will pass 4000 RPM but by placing a large demand on the engine by punching the throttle for example, the result is it digging in its heels. There is some mechanism that either stops extra fuel or does something with the ignition (hence the suspicion of knock sensors). I have tried jumping FP and +B in the diagnostic port and the pump does seem to get a higher voltage, you can definately hear it then but otherwise it is silent. It certainly sounds like the noise I'm hearing. Obviously this could be a red herring but I won't know until it's changed. The dilema is that this car is getting quite old now and I'm very reluctant to spend any money on it. My strategy now may be to run it until that pump fails and then have it replaced. If that fixes the fault, that would be great but I won't put any more money into it unless it needs it to keep it on the road. If the pump replacement is expensive, that would be the end for the car.

Have done a bit more research and by jumping FP and +B in the Diagnostic port the pump gets a higher voltage, so I'll do this next chance I can and see if it reproduces the noise I'm hearing.

Thanks for the input CuriousB. The voltage to the pump was checked a while back and its getting the correct boost of voltage. Also by driving it around I can cause the noise but creating high demand (flooring the throttle under load) so I think everything up to the pump is good, I wonder if the noise is the pump struggling to meet the demand and maybe it has never been that strong. Not trying to race the car BTW and for the money I,ve spent in total, some of which has been on tyres, etc. tha car has given good service.

...Well gents, I have done over 22,000 miles since purchase now and finally there is something that approaches a symptom manifesting itself: I have quoted SRK above as the symptom I get now (nothing else has changed apart from this, the car stil drives OK) is a high pitched whine from the rear: Sometimes as I first pull away and now I can re-produce it when I accelarate hard but as soon as I come off the throttle, the noise stops. It's like the noise is from a fuel pump or some similar component straining...yet the car starts and runs fine.

Hello from the UK. I have a question regarding the removal of the rear seats on an SC 430. Having looked at a few on the web, I notice that although there are some rear seats, the space in the back is probably unusable for anyone larger than a very small child. What I was thinking about was removing the rear seats totally and having that area re-trimmed, ideally in a very similar carpet to the rest of the car and mayby put some hide in there too. This would give me a nice area for bags, etc. Is this feasable? Are there components that sit behind the seats that would get in the way or otherwise pervent me doing this? Has anyone else done this or condidered it? All contributions welcome. Currently I'm running a LS400 but rarely use the back seats and we have other large cars in the family.

Well, I have done over 10,000 miles in this car now with no change to the original symptoms. It's had 4 new tyres and is still driving nicely. No fault codes have ever appeared. I fixed the loose wipers with a replacement wiper motor (thanks benfur) and apart from a replacement temp sensor and a couple of bulbs, it's given no problems. Regarding this 4000 RPM problem: I have a sneaky suspicion it's the knock sensors, I'll be considering getting this looked at. As always, any contributions welcome

Fixed fully with a replacement motor, easily fitted. I did mine today.

Update: I pulled fuses for: HEATER FUEL OPN FR CIG PANEL This seemed to work, as the temp indicated was now more realistic, One thing that did happen though was the 'Front' LED on the climate control panel was flashing when I switched the Ignition back on. After I pressed a few buttons on the panel it all came to life. I then tidied up the insulation on the sensor etc., looked again and the temp was -3, so I had to go through the whole re-set again. Now it seems to be working OK but I guess the sensor is on its way out. Thanks for your help guys. In order for folk to find this fix in the future I'll post this reply on both UK and USA / Canada forums and link to each. http://www.lexusowne...showtopic=76602

Thanks for this, I have just tried pulling fuse No. 6 but no change, I'll try all 4 tomorrow. Will post back with the results.

Thanks Guys! I must have triggered this open circuit when I removed it and unplugged it to give the contacts a clean. Since then I tried shorting the connections and found this made no difference. I now have re-connected it all and re-fitted it under the bumper. During a short drive it changed to -29, then -28. I read somewhere on the internet a few mins ago that an open circuit causes a -22 F reading (this is -30 C) and you have to pull the fuse for the A/C to re-set it. Whereabouts is the A/C fuse? I can't find it anywhere, I did read that the Cigar Lighter fuse is for that system and pulled that: The clock and temp display disappeared but when I fitted it the -30 reading was still there.

Hi, looking for a little help with this: Recently the readings went far too low, even earlier today it read 4 when it must be much warmer than that. I have located the sensor and disconnected it but now the reading is -30 and even after pluggging the sensor back in it reads the same, shorting the connections changes nothing. My questions are: Will this affect anything else on the car? Does the system need re-setting? Is a reading of -30 an open circuit or short? Thanks in advance