DannyM

Hey Padraig. I never drove the auto but my own preference now having owned the manual would be an auto box. I sold my IS250 about 2 years ago for the reasons mentioned above. I had really high expectations for it which I think was ultimately the problem as the longer I owned it the more I disliked it. It's probably the one car I've owned that I never clicked with. My expectations was it would be an improved upon IS200 manual. They are certainly more refined and grown up but I felt the manual option was an afterthought by Lexus. If I was to repeat I'd 100% go auto and ideally SE-L spec and just enjoy it for a daily cruiser to waft around in. I can't weigh in on the E10 impacts as I sold mine before it came into affect. I'd imagine you'd be relatively safe if you've went for something 08 or older that's been in continuous use. I'd be more concerned about something doing minimal mileage that has E10 sitting stagnant in the fuel system pulling in moisture. I'd start with the E10 additive then. The Wynns stuff is great. I use it in my bikes which range from newish fuel injected to old carburetted stuff. They do sit up over the winter with fuel in the tanks and have had no issues to date.

This may also be an option for people looking for an increase in engine noise without spending a fortune. I'd looked into the OEM Fsport intake myself but couldn't justify the price considering it's only purpose is to increase noise. Did a bit of research and from what I found the major difference is between the standard lower airbox which on the Fsport intake has an additional opening and has no ribbing inside the box. I didn't want to just cut a hole in the airbox so I took to SolidWorks and my 3D printer and replicated the Fsport lower airbox design by printing a flange similar to the Fsport design. This cost me nothing as I have all this to hand but could be an option for those who want a neater solution than a cut up airbox and something less costly than a full induction kit if you can get someone to print the flange. Does exactly what I want, increase in engine noise from 3.5-4.5k+ rpm under load and just like factory everywhere else.

Does your diagnostic have data logging/live reading function? DPFs have pressure sensors for pre and post filter pressure. I'd be looking to see if there is a big pressure difference as this would indicate a blockage.

Hi folks, Said I'd make a post here regarding the IS250 MAF sensor. I've owned my 07 IS250 Sport since September last year. I've always found the gear changes quite juttery with lots of rev hang, poor throttle response pulling away, jerky at low speeds in traffic. Read lots of topics from the US mainly on the manual gearbox/drivetrain in these cars and attributed the cars characteristics to the design. A few weeks ago I started getting intermittent faults for rich condition on both banks. Did some troubleshooting and seen fuel trims were sky high trying to lean the mix out. Given it was both banks showing rich, it was safe to say it was a calibration issue with the MAF sensor. I've had cars with faulty MAF sensors before but none had such an impact on the cars running after being replaced. Power delivery is much smoother, gear changes are no longer jerky and there's no juttering pulling away or at low speeds. Hopefully this may be of some help to someone experiencing similar issues. I had the car on diagnostics before the MAF started giving issues and fuel trims were all perfect and no indicator a faulty sensor at all. I'd say if you're IS250 is decent age like mine with a few miles on it, its definitely worth replacing the MAF. I'd never have even thought about it only for it did eventually fault out. Dan.

Taken from the Lexus Warranty and Service booklet.

If you look to the right of the factory intake tube you'll see there's a little plastic chamber connected to it. These are called a Helmholtz resonator. Without going into too much detailed, they're used to improve air intake efficiency by cancelling about pressure waves that travel back up the intake tube when the intake valve closes. They're a simple but very clever device. When these are removed the increase in noise is because these pressure wave pulses now travel back up the full intake tube and are audible. The amplification in noise actually indicates inefficiency. As said above, Lexus/Toyota engineering is excellent and its rare they cut corners on design. Performance and efficiency go hand in hand so it benefits manufacturers to design engines with as much performance as is feasible for design constraints/budget etc.

I have a 2007 on 152k and runs as smooth as it did from day 1, you can easily leave a coin balance on the radiator cap when it's running. They are overall a very solid car. The auto is definitely the one to go for. Having owned the manual one if I was to buy again I'd definitely get the auto. Only issue I had with mine is the alternator. It had previously replaced with a spurious one which died after 6 months, I replaced it with same again which didn't last long either. It's been fitted with a genuine Denso alternator plus a new battery so that should keep it sweet. It's a very well balanced chassis. I have the sport and haven't once thought about modifying the suspension. It's super compliant cruising down the road and confidence inspiring through corners. They're not the lightest car but hide their weight very well. As said, one thats well maintained shouldn't give you any real hassle. I always buy service parts from Toyota as theres very little difference in the price between OEM and spurious (at least here in Ireland anyway). Be picky and hold out for the spec you want and get one with good history and you won't be disappointed!

Did you check the clutch switch to see if the pedal is engaging it when pressed to the floor? Would seem the most likely culprit to me either pedal is not engaging it or switch has failed. Mine is very sensitive in my 250, unless the pedal is hard against the floor it won't start.

Spotted that you used an Exedy clutch kit and wanted to know how you rate it. The clutch was replaced in my 250 just before I bought it 6 months ago (OEM clutch kit was fitted). I'm not a fan of it at all. Pressure plate is quite soft, very difficult to gauge the biting point and clutch is very sensitive (it's very easy slip it on a hill start!). Did you find the Exedy any better or is it much of a muchness being an OEM replacement? Cheers.

Thanks Texas thats great info. I typically do go for OEM parts, all my services I use OEM parts and did price a Denso but given the cost difference I opted for a remanufacture unit. Now though in hindsight I'd rather have forked out for a Denso. If it's known that spurious/reconditioned alternators don't agree with the car I'm happy to pay for a genuine one. Once it's not an issue with the car causing the alternators to blow as at the minute I feel like I can't trust the car. Thanks for forwarding on that thread link. Nice to know someone has had a similar experience and resolved it.

Hi folks, I own a 2007 IS250 sport which I've had since September last year. Car has been meticulously owned by the 2 previous owners and also by myself in my ownership. I was told by the previous owner when I bought the car that there had been some maintenance carried beforehand including an alternator replacement. Car has been faultless up until February when the alternator began to fail. I replaced it with a new/reconditioned unit from a reputable company through my trusted local motor factors. The old alternator I removed was a brand I'd never heard of so put the premature failure down to that. Today my alternator died again. I inspected the wiring when I replaced it in February and again today and nothing appears out of sorts. I'm starting to suspect there is an underlying issue here. Has anybody had a similar experience with alternator failures in their IS250 or am I just so unlucky as to get another dud alternator the last time? There's nothing to indicate there's electrical problems with the car. It's not been modified, everything appears in good condition, battery looks relatively new and holds charge there's never any issue starting after the car has been sat up. Any insight or advice from people whove had similar issues would be much appreciated. Cheers, Dan.

You need to look at your fuel trims with a scan tool to see what the management is doing. I had a rich condition recently with my 250 but on both banks. I knew it was highly unlikely both o2 sensors would fail at once. Diagnostics showed negative short and long term fuel trims on both banks indicating a false MAF reading. I cleaned the MAF and all returned to normal. You need to log the short term fuel trims for both banks and see what's going on. If your fuel trims are positive, the ECU is adding fuel because the o2 sensor sees the mix as lean. On the other hand, if the fuel trims are negative, the o2 sensor sees the mix as rich and is subtracting fuel. If your trims are within +/- 5% on bank 1 then you're o2 sensor is reading correctly. If both banks are showing similar fuel trims then it's more likely a MAF issue. Pre-o2 sensor holes in the exhaust can also create false readings as a venturi effect will draw ambient air into the exhaust flow and tell the sensor it's lean. I'd start with comparing your fuel trims between banks and look for an imbalance. Being you have a lean condition your trims will be positive. If it's good on bank 1 and not on bank 2, focus your attention towards o2 sensor and or a pre sensor exhaust leak. If both banks show negative even if bank 1 hasn't triggered a fault code yet, I'd be looking at the MAF sensor. Hope that helps, Daniel.

+1 for getting an OBD2 scanner plugged in. If it's lit up the dash it will have stored a fault in the ECM. My 250 did the very same for a rich condition fault.

Hi Rustyau, I haven't worked with DET3s before but |I'm well versed in this field so may be able help you. I've pulled the data sheet from the ecumaster website which has the wiring diagrams. Closest thing listed is a Toyota Supra so you'll need an ECU pinout for the IS200. I believe I have the workshop manual for the GXE10 with the wiring schematics, I'll have a look later and get back to you. The DET3 is a piggyback ECU so it manipulates sensor inputs to fool the ECU into giving a different desired output. Your DET3 has 12V switched power plus GND. Your DET3 inputs are crank position signal and MAP signal. Then your output from your DET3 is a modified crank position signal and a MAP signal. Essentially, you'd find the signal wires from the crank position and MAP sensors, cut them and join the sensor side into the corresponding pins on the DET3 then join the Lexus ECU side into the corresponding pins on the DET3. You can trace the wires back from the pins to the ECU if you don't have a pinout diagram to determine what does what in the IS200 ECU. You can use a multimeter to test continuity and identify different circuits. I wouldn't use a test light as sensor signals are 5V not 12V. https://www.ecumaster.com/download/ Danny.

Hi all, Looking for members experiences on e-throttle controllers such as the APEXi SMART Accel. My understanding is they take the voltage signal from the pedal and boost that signal to the throttle position input on the ECU. Has any one any experience with these on the IS250? I only came across 1 or 2 old threads with reference to them. My sole purpose for wanting one would be to increase throttle response and reduce rev hang on gear changes. Cheers, Dan.