idle quality question

[skt31]

Hi all,

Looking at a 2000 NSX for purchase. The car has 32k on it and appears to have been cared for ok, if not perfectly. The 30kmi service has not been done and there is some evidence of parking lot damage (scuffs on rear bumper behind wheel). I've searched the forums a bit on the below but have not found quite as accurate an answer as I was looking for. Apologies in advance if this is beaten horse territory.

The car has a bit of a lumpy idle. Kind of like a 6.0l Chevy with a moderate overlap cam, not what I'd expect from a Honda. Revs are generally consistent, however it idles like it has a partially fouled plug. If it were a BMW I would suggest it had a vacuum leak. Normal driving seems fine. The engine pulls smoothly with no hesitation but the RPM hangs a little (0.75 sec or so?) on rev matched/heel and toe downshifts. More than I would expect for a driver oriented vehicle. RPM also drops off a bit slower than expected.

Having never driven one before I don't know if this is a "They all do that" thing or not.

Any help would be greatly appreciated.

Steve

 

[CL65 Captain]

I have a 2000 also. All perfectly normal. Idle is a bit lumpy and you can feel it through the steering wheel. Also, when heel and toe, blip the throttle and it hangs for a sec. All normal for an NSX.

If you watch one of my videos you can see that it makes downshifts easier as the RPMs don't fall and as a result you don't have to over rev to make the perfect heel/toe downshift. Lapel mic for the video camera is in the trunk so there is no wind noise and you can hear the engine well.

Oh, and the NSX is without a doubt a "driver oriented vehicle".

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[sylcurt]

Hi, and I also have a 2000, since May.

I have been so taken in by the car (driving every chance I can before winter) that I hadn't really noticed it until recently, but I have a very similar problem...(if it is even a problem...so I will say "observation")

Cold start - idles about 1300 and fairly rough or "growly" sounding for about 3 mins...then (on its own) drops down to about 750 RPM and is perfectly smooth and quiet, no vibration felt at all.

If you then slowly increase throttle through the RPM band while in neutral, it gets very rough over 1000 RPM and stays very rough until about 2200, then progressively gets smoother and less vibrations. by 3000 its pretty much gone...

When I say rough, its like "really rough"...shakes the cabin, steering wheel, and also sounds bad, like its "missing" or something....or like something is out of balance...

I don't notice it while driving /shifting, since the car is so stiff, you tend to feel other bumps and shakes in the road more so than engine vibration....

I searched many hours on Prime last weekend using key words like "rough idle", "engine vibration". etc....and found lots of great write ups. Most said "normal"....so I am not overly concerned, however, some talked of engine mounts, dirty throttle body, valve adjustments, etc....

LarryB was kind enough to suggest I check my coil packs, so I ordered some new ones, and when they come, I will just change them to be fresh....regardless, and do plugs at same time.

I have 36,000 miles, and previous owner did have TB/WP done at about 33,000 miles an Acura Dealer.

I have a hard time accepting that normal can be this rough, especially for a Honda ....my TL-S sits right beside it, and if I do the same thing.....there is not even a ripple of vibration or roughness right from idle allt he way up....nothing at all...just smooth as can be...I am no technician, so maybe that is not a fair, given the way the engines are designed and set up. My MDX is also as smooth as can be.

So, I am now also going to search out instructions on line for cleaning throttle body and such, and see what else I can do on my own before reaching out to the dealership.....

But there is a lot of information on the topic if you are interested in doing the reading. I am actually thinking of doing a you tube video of it, and posting it to gauge form others if it is in fact "normal" or not...

 

[tbromley]

What you guys are describing is the typical cold start/warm up process I'm very familiar with in my 91. It's a bit rough upon cold start and idles up around 1200 to 1300 something like that depending on how cold it is, then as it begins to warm, and I don't warm it up a lot when I drive it, I warm it up under load by driving it easy, it then drops to the normal range of 750 to 800. Runs smooth and the warmer it gets over about 20 mins the more smoothly it runs. I'd say that is pretty normal for this engine - it is not like your TL. The engine in a TL is toned down and I would think the cam profile is a bit different - maybe a lot different. Hope that helps.

I don't worry about it at all.

 

[sylcurt]

Hi Tim, yes, indeed the idle does level off after a couple of minutes, but I am describing how after driving, whether 30 mins or 2 hours, the idle is still very smooth with no press of the accelerator...just the normal minimum idle spot..., but slowly "revving it" upwards through 1000 and up to 3000 (while parked) it vibrates and sounds quite bad....this is where it differs from the TL-s because doing the same thing there is no shake or
"hikuping" like in the NSX....

 

[usafdarkhorse]

A 90 degree V6 will have a slightly lumpy idle. Feels like it's missing, but it's not. Rest assured.

 

[LJZ]

My /94 (which is totally stock and perfectly tuned) has this lumpy idle as well. When compared to my TL it is very noticeable but as per some of the prior posts, my master Acura tech's advice and numerous posts on Prime and in the Wiki (I believe), the normal idle characteristics of the 3.0 litre engine are consistent with my experience and some of what has been described in the posts above. I think those of us who have Honda products are used to very smooth running engines at all speeds -- the NSX does indeed have a band of what I'll ineloquently term "not so smooth operation" but once north of 2,000 rpm it smooths out very nicely. I only notice this roughness at idle (primarily on my car between 1,000 and 1,500 rpm), not upon acceleration. On the other hand, my engine is very smooth from 3,000 - 7,500 rpm and the soundtrack is glorious. :smile:

 

[usafdarkhorse]

The difference between the TL and NSX is aside from displacement.

The TL is a 60 degree V6 and the NSX, a 90 degree V6. Their idle and rev range characteristics are primarily different due to their balancing. A 60 degree V6 is typically used for a smooth engine. V8s are usually 90 degrees.

 

[blvnhim]

Jim(captain) is spot on with his answer. Sometimes----sometimes it will help to loosen engine mounts and retighten. :wink:






_______________________________________________

"Simply put, the cost of owning a vehicle is the difference between what you pay for it and what you sell it for. There are many factors that influence resale value; miles, exterior and interior condition, maintenance history, etc"

 

[cosmod250]

http://en.wikipedia.org/wiki/V6_engine

Check out this wiki about V6 engine design, interesting reading.

Peter

 

[sylcurt]

Very interesting indeed...I had no idea...

Oddly enough, I had the TL predecessor, the Vigor for a while with its 5 Cyl engine and it was exceptionally smooth.

But points well taken, the NSX is no TL, nor is it meant to be ....its just hard for an off the street guy like me to understand when an engine, especially a Honda engine, is not 100% smooth at all rpm levels....but like many things..."it is what it is"...

Coil packs are ordered and on the way, so I'll change them anyway, along with sparky's, ...can't hurt to do so....I'll report if it made a difference....

 

[Zenzanon]

Idle Air Control Valve?

 

[sylcurt]

Idle Air Control Valve?

Are you suggesting that this may be the culprit, or wondering what this is?

 

[LJZ]

sylcurt -- just noticed you are a fellow Canuck. I'm originally from Toronto but have been living in Michigan for past 20+ years. You may or may not have a problem with your NSX insofar as idle characteristics are concerned but it sure sounds like your car has the typical NSX idle. Are there any other NSX owners in proximate to where you are? I'm sure this has dawned on you -- would be great to connect with a few other owners and get a ride/drive in their car to see if they have similar idle (of course if the other car(s) are either turbocharged or supercharged this won't be a good comparo assuming your car is stock). This will give you a benchmark and if their cars idle pretty much as yours does there's nothing to be concerned with. Just a friendly word of caution -- you might wind up spending lots of dough/time, etc. chasing down this problem which may turn out not to be a problem at all. The real problem is that techs who have lots of NSX experience are few and far between. Most of the Acura dealers do not see NSXs very often at all (this is the case here in the greater Detroit area and I suspect is the case where you are, and perhaps even more so). Thus, the dealer may not be your best bet. I suggest that if you can't find any other owners proximate to you, next time you are travelling you post in advance of your trip on Prime to see if there is anyone where you are going that is willing to meet you so you can see what their car idles like. The folks on Prime are a great bunch most of whom are happy to help out. For what it is worth if you ever find yourself passing through Michigan let me know -- happy to let you drive mine. Final word -- this is a fun car but not without certain idiosyncracies -- very, very different from our TLs and to fully enjoy it I think you have to keep this in mind. To be honest, there are some days that I prefer the serenity/smoothness/ride qualities of the TL. But then there are those days that I really enjoy the NSX experience!

Cheers,
Jeff

 

[sylcurt]

Hey Jeff, thanks for the encouraging words....I am beginning to think all is normal. When I bought it, there was a PPI done in California for the car at the dealer, and I also had a full checkover done when I got it home at the dealer in Winnipeg. Both cases suggested nothing wrong or abnormal....so its all probably ok.

I got my coil packs last night and have picked up some new spark plugs that I will try and do myself in the coming days. It may or may not help. I figured since the car is 10 yrs old, it can't hurt to do this.

And you are very correct....some days the TL is the way to go, and others, often after work in early evening, the NSX is the place to be...and drive it for pure enjoyment of driving.

I think there are a few other NSX's in Winnipeg, and although I'm 90 miles away, maybe at some point we'll all hook up, and we can do some comparisons.

I received my STMPO rear strut bar last night, and as well, assembling things for the Stereo installation over the winter. So I have a few projects to sink my teeth in to. I am really looking forward to this project and getting to know my NSX better from the inside out.

Curtis

 

[Zenzanon]

Are you suggesting that this may be the culprit, or wondering what this is?

I'm saying that it may be the problem (I didn't see anyone else mention it in the thread). Once those things clog up they can cause your car to shake (I'm not sure about the NSX, but for older Accords this is a common problem).

skt31-
Does the shaking noticeably decrease when you lightly press the gas in neutral (maybe bring the rpms up to 1.2k, anything above normal idle revs)?

Also, does turning on and off the AC while idling cause any noticeable differences?

 

[Rob4092xx]

The only shaking in my 2000 NSX is my butt when I get giddy driving it!