I have a big, puzzling problem and I need others' experience and advice. It’s kind of urgent, too, because the local Reno, Nevada, Honda dealership is suggesting that it will charge me for a bunch of hours of mechanic time on a warranty problem that I brought my 2006 S-2000 into them for:

A month ago, about the same time as I put on a set of Hankook winter tires on some used 16” S-2000 rims that I bought for the Hankooks, I developed what I think is a throttle problem. When I let off on the accelerator pedal while in gear or while out of gear the engine speed stays high. An example is shifting down to 3rd from 4th at about 4000 rpm, when I put the clutch in and took my foot off the accelerator the engine speed would stay at about 3500 rpm. In the past, it used to drop rapidly when I took my foot off the accelerator pedal. Same thing happened when I am coasting to a stop sign -- with my clutch in or out and the shifter not in a gear – the engine speed used to drop down to 1000-1500 rpm but now it stays up at about 3500 rpm and drops real slowly down to 1500. In gear the engine doesn’t slow the car down very much at all when you take the foot off the gas, always staying at 3500-4000.

Since I have only 11,000 miles on the car and it is still under warranty, I took it to the Honda dealer service department. After the first day it was there, they said that they couldn’t figure out what the problem was, but thought that it was the radar detector and power amplifier direct power hookup to the battery that was causing the problem. I told them that those hookups had been on the car for two years and that they had never caused any problems before. They disconnected the two hookups, but the problem persisted. After a week they brought in a real expensive S-2000 computer piece from another S-2000 in California that operates the whole car and switched it out with mine, but the problem persisted. Then they told me that they had to get a certain computer piece off the assembly line in Japan that regulates the speed of the wheels on turns for safety. I forgot the name of the computer piece, but apparently it is relatively new and only on certain high performance cars now, but will be widely used this year on all cars. They said that the piece had never gone bad before so there were no parts in stock in the U.S. Ten days later, it arrived from Japan and they changed out my part, but the problem persisted.

Today I was asked to bring my stock rims and the tires I used before the Hankooks to the dealership so that they could check if the problem was the new Hankooks. The Hankooks are the ICEBEAR W300: Fronts are 205-55R16 and rears are 235-60R16. The tires and rims were recommended by a longtime tire shop owner who sponsors SCCA autocrossing and racing in the Washington, DC area. He is also a seasoned car racer, having raced at Daytona and many other places. I bought a set of the Hankooks from the Reno Discount Tire shop in a hurry when it started to snow one day and they put them on. The Honda service guy who is managing my car today told me that the problem is my rear tires were too big and that they cause a “rake” in the car that was the source of the problem. He said that the day before he had borrowed a set of tires and wheels off a 2001 S-2000 that was on the lot of the neighbor Chevrolet dealership with only 2000 miles on it. He said that when he put those wheels and tires on my car, the problem was gone. I went over to the Chevy dealership and checked the car wheels and tires: it has 16” 5-spoke rims with a Honda symbol on them and new-looking Sumitomo HTR 55 tires. Fronts were 205-55R16’s and the rears were 225-50R16’s. I drove that 2001 S-2000 (with the Sumitomo’s back on) and it was fine on the rev-down when I took my foot off the accelerator.

When I went back to my Honda service guy and asked to drive my car on the Hankook’s to see if the problem was still there, he said that I was not allowed to drive it because the Service Manager had declared it unsafe to drive. He also said that it was likely that if the problem turned out to be the new Hankook tires and was not a warranty problem, then I was probably going to have to pay for all the mechanic time of over 50 hours. He said that on Monday (November 16th) that the mechanics were going to put on my 17” stock rims with my summer autocross tires on to see if the problem appeared or not. I explained that other people had used 16” rims on a 2006 S-2000 and different tires on both 16” and 17” S-2000 rims without any problems, including me. The tires that I am using in the summer are 3-year-old Toyo Proxes RA1’s: Fronts are 225-40R17 and the rears are 235-40R17. I don’t remember whether I had the throttle problem before I took these off and put on the Hankooks, but I don’t think so. I think I only noticed the problem after I had the Hankooks put on.

I would appreciate the feedback and experience of any S-2000 owners on what the Reno Honda dealership is trying to do to me. I hope that the experience of members of s2ki.com can give me a way out of this mess that the Honda dealership here has got me in. I don’t know what is going to happen Monday when the Honda mechanics drive my car with the 17” stock rims and the Toyos, but it may be that it drives fine with no throttle problem. If so, the dealership is going to try to charge me, from what the service guy dealing with me has said. Another thing: The Reno Discount Tire manager who sold me the Hankooks says that he doesn’t believe that those tires could be causing the throttle problem. He also said that he would swap out the rears and fronts to a lower profile if I wanted to do so – I only have about 50-100 miles on the Hankooks. Does anybody have a solution – or a good contact in NHTSA? Help!

Please let me know what you think. Thanks in advance. I am stressed and have been without my beloved car for one month.

 

since you have an 06 the VSA (vehicle Stability assist) will look to see if the front wheels are spinning @ the same speed as the rear wheels.

Since you have tires which are not the proper sizes, (ie rears larger than the front) the VSA thinks the wheels are spinning @ different speeds. VSA can directly control the throttle plate in order to correct the speed of the engine or it may apply abs to correct the car. VSA was holding the throttle plate open to try and correct what it is seeing from its wheel speed sensors. VSA has no idea you changed tire sizes and therefore is not understanding what is happening.

In most cases improper tire sizes f/r will cause the VSA light and ABS light to come on and it will disable those functions, but in your case it may not have been extreme enough and simply caused VSA to freak out.

Moral of the story is you should run the correct tires.

as for what Honda is try to do. Well that's their fault for not knowing their own product. too bad for them. It should have been obvious you didnt have the right tires on the car. They followed the wrong path for looking into your problems.

 

additionally, it wouldnt matter what year s2000 wheels/tires you used so long as they had the proper overall diameter tires. 16" or 17" doesn't matter so long as the circumference or revolutions per mile are similar enough between the front and rear tires.

 

^^

 

50 hours?! They're right that the rear tire size is WAY off (2" bigger in diameter than stock!). But where in the HELL are they getting 50 hrs of labor for the "work" required?

You need to get some 225/50-16s for the rears, that's all. If they're that nuts about what they're going to charge you, and won't give your car back, man, I dunno...

 

If the tire place will swap out the tires, that's the thing that needs to happen. Troubling that they put the wrong size rears on in the first place, and now they think they have to go to lower-profile for the fronts and rears? Wrong again.

Tell them the fronts are fine and you need 225/50-16 rears.

 

if that doesnt do it, check to make sure your vacc hoses are all good. Its weird that clutch in doesnt make the rpm drop..

 

my first guess would've been the floormats pushed up behind the pedals. i had that happen four cars back, i'd take my foot of the gas and it'd keep accelerating, scary thing to have happen on 290/190 in worcester during rush hour traffic...

 

I don't think VSA is capable of modulating throttle on our cars, and I certainly don't think it would ever use MORE throttle than you called for. My understanding has been that this system merely actuates one or both rear brakes, (inside for understeer, outside for oversteer), and that's it. I don't understand why your dealer hasn't replaced the throttle position sensor for your Drive-By-Wire system. That would have been the very first thing I would have done. The next thing I would replace would be the motorized throttle itself.

Honda's VSA and TSC systems just give up and turn on the error warning light if they get confused (I've had it several times in both my cars on stock wheels/tires). They aren't going to suddenly start holding the throttle down.

 

For what it's worth, my dad had the exact same problem with his DBW Boxster S when shod with tires with a different front-to-rear diameter difference than stock.