Sluggish Acceleration

[Diapason]

Hi folks,

I mentioned this problem here before but now I'm at the end of my tether so I'm going to ask again! I'm not sure which bits of the following story are relevant and which bits aren't, so excuse me if this seems a little rambling. If anyone can shed *any* light I'd be most grateful.

I got my IS 6 months ago and loved it. About 3 months ago I decided to splash out on new tyres all round. Great. On my way home, trying to get used to the new "feel" I had the impression that it wasn't accelerating so well, and that the car wasn't as lively as before. I thought it was probably just my imagination and next time I drove it all seemed back to normal. However, over the next few weeks, the sense of sluggishness occasionally returned. Basically, it felt like the car was being "held back" somehow, not pulling as well and seemed to come to a slow much sooner when you released the throttle. It also seemed a little noisier, not as refined. For a while this was intermittent, sometimes coming on in the middle of a journey. I needed new brake pads and I thought it might be something to do with that, but after I replaced the pads things were still the same. As time went on the sluggish feel became more and more prevalent until it was like that all the time.

A couple of days ago the car was on a ramp and the wheels were off for an unrelated issue. When I got it back, everything was at it used to be. The car was like it was when I bought it. I took it out driving, relishing the change, enjoying the proper acceleration, happy that it was quiter. The refinement was back. It was effortless. Also, the car had been shaky at motorway speeds and I'd just put it down to wheel balance. Now though, things seemed smoother. Before, taking your foot off the throttle at 80mph had LED to a kind of juddering through the car, but now that also seemed to be reduced. This new found enjoyment lasted for an evening. Yesterday, the old problem was back, and at this point I decided it definitely wasn't my imagination and it was time to get it sorted.

So, earlier today I dropped it out to a Lexus dealer, explained the problem as best I could and left it with him. He took it for a drive and came back saying he thought it was driving fine, and that it seemed like a normal IS200 to him. He put it on the diagnostic machine which showed no problems and he put it on a ramp and couldn't spot any visual problems with brakes or whatever. He was extremely nice, listened to what I had to say, took me seriously, but ultimately I know he thinks there's nothing whatsoever wrong with it and I'm just imagining things. So, short of going for psychological assessment has anyone got any ideas??? Getting to the bottom of this would make me a very happy man!

Si

[kam05]

Whats the mileage on the car?

When was it last serviced? (ie: last oil/filter/spark plugs changed)

Bet it could do with a service

[Parthiban]

Did you ask the dealer whether you could directly compare one of their IS200s against yours? That would make it much easier to notice any differences

[Diapason]

Mileage is 32,000 miles. Serviced by non-Lexus dealer in April just before I bought it, although I'm not sure exactly what was done. The service history on this car is a little scant. It was serviced regularly, but not by Lexus dealers, and there are no real details of what was done.

Si

[Diapason]

Did you ask the dealer whether you could directly compare one of their IS200s against yours? That would make it much easier to notice any differences

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He said that if I still think I'm having problems next week I can go back to him, and he mentioned doing exactly that. I'm still not sure if that will persuade *him* though, although it might persuade me that I'm mad/not mad one way or the other...

Si

[kam05]

Mileage is 32,000 miles. Serviced by non-Lexus dealer in April just before I bought it, although I'm not sure exactly what was done. The service history on this car is a little scant. It was serviced regularly, but not by Lexus dealers, and there are no real details of what was done.

Si

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Did you buy it from a Lex dealer/independant garage/private?

If you bought it from a garage, did you get any sort of warranty? If you did, I'd take it back and get them to take a look

Worth a try

[Diapason]

Bought from an independent, who was in it the other day and, as luck would have it, that's the day it was driving fine! To be honest, I'm reluctant to bring it back to him for a multitude of reasons that I won't get into. However, the dealer in question has told me that if I've lost confidence in that particular car and wanted to come up a year he'd have no problem taking my current car back. That's an option I want to leave open since, despite the low mileage, I would be tempted to trade up a year if I can't get this sorted. In any case, this particular problem started after my warranty ran out.

Si

[kam05]

I would get the car serviced by Lexus, get them to do the 40k service, as you have said your car has been serviced by non-Lexus garages in the past and you are also unaware of what items have been serviced on the car up til now

Have you considered getting the RAC/AA to give the car a once over?

Also, have you reset the ECU?

[Diapason]

I have not, in fact, reset the ECU and that is the first thing I'll be doing now that you mention it. Am I right in thinking you just disconnect the Battery for a while? Anything else I need to know?

I agree with you about getting the car serviced. I think it probably makes sense to do the simple stuff first as I believe in my heart of hearts that the problem itself is simple. Besides, I intended to have a proper Lexus service (and I was thinking 40k given the age of the car) prior to next February when I have my NCT (Irish equiv of MOT). It can't hurt to move that forward a little.

Getting RAC/AA to look at it is an option I hadn't considered. I think I'll exhaust the Lexus dealer options first and then consider this one. I know it's pricey, and money is a *little* tight at the moment. The Lexus dealer this morning was decent enough not to charge me anything for giving it the once over. To be fair, it's possible that on a more serious drive he might notice something, but since I wasn't booked in today there was no time for that. Still, it's a good suggestion to get the AA to look at it if I get no joy.

Si

[Niraj]

Broken / faulty Oxygen sensor? Limp mode? just hazarding a guess... easily missed, while checking over, as the underneath is all neatly wrapped up with plastic guards.

Might also be worth checking, changing the airfilter to make sure there is no restriction or blockage of air to the engine.

[kam05]

This is how to reset the ECU:

http://www.lexusownersclub.co.uk/knowledge...ex_v2&id=38&c=5

If you disconnect the Battery you will loose all your settings such as radio presets etc

[Diapason]

Niraj, I also was wondering about the air filter and whether it might have something to do with it. I'd say it's never been changed. I'll have them check that when I go back to them next week. I just wish I knew a little bit about cars so I could go and have a poke around myself. I really hate being ignorant of such things and having to trust others to sort things out for me. It's just not my style!

Thanks kam05 for the link. I can cope with losing the presets. I hardly ever listen to more than 2 or 3 stations anyway!

Si

[Niraj]

Niraj, I also was wondering about the air filter and whether it might have something to do with it. I'd say it's never been changed. I'll have them check that when I go back to them next week. I just wish I knew a little bit about cars so I could go and have a poke around myself. I really hate being ignorant of such things and having to trust others to sort things out for me. It's just not my style!

Thanks kam05 for the link. I can cope with losing the presets. I hardly ever listen to more than 2 or 3 stations anyway!

Si

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My guess would definately be to do with flow of air... be it past the oxygen sensor, or air into the engine... i've not experienced the problem myself, but then, i've only had my car for a few months, and my previous car, i always serviced myself.

[lexicon]

Unlikely that a blocked air filter would cause symptoms that come and go like that. Also "physical" problems like juddering and losing more speed than expected "off-throttle" sound like maybe a sticking brake caliper - interesting that it was better after the wheels had been removed & replaced.

[Diapason]

Unlikely that a blocked air filter would cause symptoms that come and go like that. Also "physical" problems like juddering and losing more speed than expected "off-throttle" sound like maybe a sticking brake caliper - interesting that it was better after the wheels had been removed & replaced.

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That's where I've been coming from with this from the word go, simply because it just seems like too much of a coincidence that this started when it started. For a while I had myself persuaded I had a sticking caliper but now I'm not sure. Deep down, I still think there must be something causing friction where there shouldn't be friction. Could something as simple as corrosion around hubs (or discs or whatever) cause this? Maybe if the car is on a ramp for a while things settle in a different position, but once the wheels are bearing the load for any length of time they revert back again?

I'm getting my girlfriend to drive the car home this evening to see if I'm crazy. Of course, given that I'm letting her drive, I *must* be crazy...

Si

[lexicon]

Unlikely that a blocked air filter would cause symptoms that come and go like that. Also "physical" problems like juddering and losing more speed than expected "off-throttle" sound like maybe a sticking brake caliper - interesting that it was better after the wheels had been removed & replaced.

←

That's where I've been coming from with this from the word go, simply because it just seems like too much of a coincidence that this started when it started. For a while I had myself persuaded I had a sticking caliper but now I'm not sure. Deep down, I still think there must be something causing friction where there shouldn't be friction. Could something as simple as corrosion around hubs (or discs or whatever) cause this? Maybe if the car is on a ramp for a while things settle in a different position, but once the wheels are bearing the load for any length of time they revert back again?

I'm getting my girlfriend to drive the car home this evening to see if I'm crazy. Of course, given that I'm letting her drive, I *must* be crazy...

Si

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Corrosion on the disk faces (ie the braking surface) would be a symptom, not a cause of a sticking caliper. It's possible that an excess of corrosion not on the braking surface could interfere with pad operation, but I doubt that's your problem.

Are all the faces (both sides of each disk) nice and clean when you've been out for a run?

If you put it on jacks/stands, do the wheels spin fairly freely?

Also is your handbrake OK - this operates a separate brake mech' on the inside of the rear disks. I've had problems with this setup on other cars due to poor servicing (not Lexus).

[Diapason]

The outside edge of the discs are fine, and wheels spin reasonably freely when jacked. One side at the front spins a little more freely than the other, but the Lexus guy today said he thought that was fine. I didn't ask about the handbrake, but I've never had any obvious problems with it.

I'll try to look at the inside faces of the discs if I can.

Meanwhile, I'm out of here for the weekend. Thanks for all the suggestions and I'll report on Monday.

Cheers,

Si

[andrewxsi]

Maybe the snow mode is activating its self if you know what i mean, then you are losing power.

[vinokirk]

I got this problem!!! My brakes were squaky so i got a garage to grease em up them when i got the car back it seemed sluggish, like id put my foot down and nothing would happen for a few seconds then woosh id get acceleration, like the throttle cable was broken or something!

What is snow mode? maybe i had that on, it hasnt happened since

[Rob]

snow mode reduces throttle response - lowers the rpm for the same throttle position and also allows the wheels to spin without the traction control coming on

useful in conditions like these

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[Tony9r]

This may seem like a silly question, but have you turned your air conditioning completely off to see if there's any difference?

On my GS, there's a noticable difference in acceleration when the A/C pump is active as it saps away several bhp... just a thought