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TCS Malfunction???

Edo

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My TCS light comes at while cruising in second gear on dry pavement with no input whatsoever. (No acceleration no deceleration). The roads are usually flat, with no ripples or bumps whatsoever, yet the Green TCS light under the speedo turns on and you can feel a definite hesitation in the throttle, sort of like Hiccups from the engine. This also happens occassionally when you go from partial throttle to Full throttle. The NSX as far as I know is not exactly a "torquemeister" like a Viper, and once the tires are hooked up, they should not break away yet again at 4000rpm's. (Which is when the TCS comes on) Does anyone have experience with this sort of thing? Is it a premonition of bad things to come? Or are the tires maybe inflated incorrectly?
205/45/R16 front 255/40/R17 rear.
 

Lud

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You are running smaller front and larger rear tires than stock. Try the car with tires that keep the OEM size ratio and see if you still have the problem.
 
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I have been using the same size as Edo for awhile without any problem whatsoever. I'm not an expert, but my understanding is if u increase the rear and decrease the front. You would even have a later response time from the TCS. Is that true?? anyone?
 

Edo

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I just bought the car, so I dont know what the last owner experienced as far as TCS problems went, but would slight differences in Tire pressure also cause the same result? especialy since the tires are the wrong size? I cant remember off the top of my head, what IS the stock 17/16" tire size anyways?
 

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Stock for the 16/17 wheels is 215/45-16 and 245/40-17.

You *should* be able to use the sizes you mentioned with TCS. You're about 3% off the stock sizes and typically you can go towards 5% before TCS barfs. In fact Andrie mentioned he is using the same sizes without a problem.

However, if you are having TCS problems the first thing I would try is going back to stock tire sizes. If you know other owners in your area that's a cheap and easy test - just swap wheels for a few miles and see how it reacts.

Slight variations (a couple PSI) in tire pressure should not cause the problem, especially if you are cruising at a constant speed on a smooth flat road as you described.

If something is broken, the most common problem that would give the symptoms you described is a bad pulsar ring at one of the wheels. But I always like to try the cheap and easy fix first which is why I suggested trying stock tires. Of course if you don't know any owners nearby that may not be cheap or easy <g>
 
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What year is your car? If it is an early one, the tire size is definately an issue. Early TCS settings were so sensitive that it was almost impossible to use aftermarket wheels, so Honda recalibrated the system. Even less than 2% or so on an early car will activate the TCS. There are even reports that on the 91s, tire wear will start causing TCS problems.

Does it also come on in sweeping turns? If tire size is the problem, that should also be happening.

If you have a later car and the RATIO of front to rear rolling diameter is within 5% of stock, I suspect something else is wrong.
 

Edo

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Well, I have a '91. With aftermarket 17x9.5" and 16x8" wheels. The tire sizes are as stated above. Is there something I can do to make the TCS less sensitive? The TCS light only seems to come on during cruising at high rpm's. ie: holding at 4000rpm's in 2nd gear.
Also jumping on the throttle at speed also seems to do it. I havent noticed it in long sweeper turns, mainly because I am either A)watching the corner, or b) driving hard enough for the TCS to activate. I live in Vancouver WA, so I dont think there are many NSX owners that I can just swap tires with..I'm going in for a new timing belt here in a couple days. I will ask the Acura Tech about the Pulsar Ring thing.
 

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If it comes on when you nail the throttle I'd tend to suspect it's just overly sensitive instead of a bad pulsar sensor which would be more random.

The only way to adjust the sensitivity is to replace the TCS computer which is fairly expensive if it's not goodwilled by Acura. There have been a number of running changes to the software over the years.

Even if you're not looking at the dash through a corner you should be able to feel TCS if it activates.

[This message has been edited by Lud (edited 30 May 2000).]
 
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Since you have a '91, I would bet the house it is the really sensitive TCS algorithym and not a faulty sensor. Replacing the computer is really expensive, and I don't know if it is a straight swap. If it is really bothering you, you probably only have two real choices - 1) disable the TCS (it's not that great of a system on the NSX anyway) and, by the way, I have no idea how to do this, or 2) get new tires that will get you back within system specs.

I would opt for number two. The car goes through tires pretty regularly anyway, so just get it right with the next set. There are both 16"/17" and 17"/18" wheel/tire combinations that will work on your car.

Keep in mind that the '91s are super, super sensitive so try to stay within 1 or 2% of stock if you can. No more than 3% max. Also, it is the RATIO of the rolling diameters that you have to keep within spec. The tech guys at Comptech were really helpful when I went through this same BS with my 91. They can help you out with tire sizes that will work. Then shop around and get them cheap somewhere else.


[This message has been edited by David (edited 31 May 2000).]
 
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Did I buy your car or what? I had the same problem on my 91 with 205/50/16 front 4% too large and 245/45/17 rear 3% too large. Aside from the tires being too tall and not wide enough this was not the problem. Turned out I had a fractured solder joint on the main relay which would cause an error in the TCS. Solution resolder joints. To determine if this is a possible error for you you can put an oscilloscope on the Vcc line going into the ECU and TCS and look for a temporary glitch. Otherwise it is most likely a contact problem at the ECU or TCS modules. Get some contact cleaner and visually inspect the connection. By the way I live accross the river in Portland.
 
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I have a 91 with 215/40/17 and 265/35/18 and have never seen the TCS light come on....ever. Even when I had the stock setup. You all make me wonder if it even works..... if it is supposedly so sensitive. What test can I do to check if it works? I've driven it hard into corners but not too often. Didn't notice a thing. Even when I've hit bumps (although I try to avoid them), nothing has happened......

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Edo

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I'm not sure but NSxotic I think you might have the right ratio of tire sizes..I'm Running 215/45/ZR16, and 255/40/ZR17's which if I recall right are slighter smaller and slighter larger than stock. The TCS is very easy to feel, its like a slight hesitation in the throttle, at least it is in my car...in fact, what does it feel like for you other guys? Is my TCS even functioning the way its supposed to?
 
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Edo,

I have exactly the same throttle hesitation symptoms that you describe. They go way when I turn off the TCS, so I always turn it off, because it never rains in southern CA.

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Engaging the TCS is very simple. Next time it rains, rev engine to 3000RPM and dump the clutch. TCS should engage when your tires start losing grip on the pavement. It'll feel like there's major hesistation in the engine. You can do it on dry pavement as well, you'll just have to rev the engine higher. I don't recommend dumping the clutch very often as it's definitely not good for your clutch.

FYI: I can get the TCS to engage from 1st to 2nd shift when I shift at just before redline.
 
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Nsxotic,

To test the TCS put your car on jacks. Put it in second gear and increase the speed over 20mph. The TCS will start choppiong the throttle. Actually you can do this in any gear. The speed at which it cuts in changes.

Driving test: At a stop sign put it in 1st and hammer on it while taking an immediate corner. It should engage.

You can go on a dirt road if your not worried about rock chips and try to get a fish tail going. The TCS will engage and stop you from throwing some major roost.

Your beefy tires probably have much superior grip that TCS is not activated very often.
 
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Thanks Scott, but all those options are too cruel to do to my 'first born'. It drives perfectly and is never a problem in the rain so I guess I'll just consider it 'in working condition'.
smile.gif


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The only one that sounds potentially "cruel" is the dirt road. The others won't hurt a thing. Just nail the throttle from a dead stop in a wet parking lot sometime and you'll see if TCS works or not.
 
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scott said:
Did I buy your car or what? I had the same problem on my 91 with 205/50/16 front 4% too large and 245/45/17 rear 3% too large. Aside from the tires being too tall and not wide enough this was not the problem. Turned out I had a fractured solder joint on the main relay which would cause an error in the TCS. Solution resolder joints. To determine if this is a possible error for you you can put an oscilloscope on the Vcc line going into the ECU and TCS and look for a temporary glitch. Otherwise it is most likely a contact problem at the ECU or TCS modules. Get some contact cleaner and visually inspect the connection. By the way I live accross the river in Portland.

My TCS light comes on when the TCS is SWITCHED OFF. When this happens the engine is cut for a split second and then normal operation resumes. It has happened when cruising on the freeway and at the track.

I had the TCS fuse pulled (the one in the fuse block next to the radiator overflow tank) and it still happened (the engine cut still happened, the TCS light was on all the time with the fuse pulled).


Where is the "main relay" you refer to? Pages 23-7 through 23-12 of the '93 service manual show several relays but none labeled "main relay".

Thanks!
 

Edo

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Talk about a thread revided from the dead...I havent logged on here in like 2 years...

But anyway..just pull your e-brake handle up 1 click and drive for a short period of time. The ABS and Traction control system should shut off completely.

That should remove any problems you have associated with the TCS. If it still has issues, then its not TCS..but something else.
 
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This definitely sounds like the PGM/FI relay failure that I experienced a couple of years ago. The relay is located behind the passenger-side seat IIRC (you'll need to remove the interior trim panels that cover it). The solder on the PGM/FI relay's circuit board appears to develop cracks over time, which eventually lead to a momentary lost connection from time to time. When that happens, the car will hesitate for an instant, the RPMs will drop (for an instant), and the TCS light will flash.

In my case, I ignored the problem for a few weeks as it gradually got worse. It got to where the rougher the road was, the more frequently the problem would manifest itself. Eventually, the relay died - I resoldered the connections on it to get it working again while I waited for a new one to arrive from Niello Acura.

If you do a search for PGMFI or PGM/FI relay in the forums, you should see several stories from people that encountered the same problem. You can solder the piece yourself if you feel handy, or you can order a replacement for something like $60-$80.
 
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