Idle bobble...

[NoSeX4U]

Before some of you jump all over this, firstly it's 'bobble' not 'babble' (for which I think I've been censored ) and, yes I did a search and read the FAQs and only found an eliptical reference to my problem being 'bad'. Here it is:
During the course of a drive I will occasionally watch my tach dive from 800rpm and smooth down to 3-500 in a surging fashion with the attendant roughness in the engine. And though it never stalls, I can only think this will eventually happen. One suggestion I uncovered was to 'check the PGMF 1 post' but whether this is a post from a member named PGMF1, or some part of my car, I have no idea...at any rate that's as far as I got. Can an O2 sensor be checked manually? This problem asserts itself at any time, not at start-up, not just on hot days, and not every day. It's there, then it's gone. I'm sure this has been discussed before, but at the risk of ruffling feathers or having this post also simply 'disappear', I'll post and take my chances, as I'd like to see this problem go away.

 

[NSX/MR2]

Check all your coil-packs to see if they are all firing in the range.

 

[brahtw8]

I think they meant PGMFI, which I believe stands for ProGraMmable Fuel Injection

 

[Larry Bastanza]

NoSeX4U,

I suggest you have your throttle body cleaned. This is a common problem on all Honda automotive products. Civics to NSX's!!

HTH,
LarryB

 

[jadkar]

OK - Here goes my 2 cents. Warning.. it may not apply here, but it may help you in figuring out the problem. I have owned 4 crx SIs and on the 1.6 versions I could adjust my idle/air mixture, doing this slightly adjusted my idle speed. However, if I moved the screw too much out of it's acceptable range I would get a surging at idle. Car would go from 900rpm to about 250, almost, but never stalling. I think the PGM-FI unit was trying to compensate for a screwed up mixture, and it couldn't find a sweet spot so it would continue to "hunt" which in turn surged the idle. That adjusting screw was near the throttle body, and covered by wax from Honda so nobody would touch it. I'm not sure if the NSX has this or not, but somebody should know. The other component that would do this on the "mini X" was the "idle air control valve" which sat on the back on the intake. When I worked for Honda I saw these things go bad a lot which made the idle surge.

Now, I'm not sure if the NSX has these 2 components, but it's worth looking into. Actually, I'm sure someone will chime in.

 

[BladesNSX]

I too had this problem. I believed it to be a dirty aftermarket filter. I cleaned the filter and the problem went away for a short while. But, soon after it came back. I talked to my mech. and he believed it to be a dirty throttle body. He cleaned the throttle body and gave the NSX a tune up. The problem was gone; however, came back soon after. Eventually, we discovered the problem was with the battery. How? I don't know. The OEM battery was basically going dead, incapable of holding a charge. I purchased the a lightweight gel packed battery and the problem has since been gone.

Hope some of this helps.

 

[wswen]

Idle Speed

I purchased a 1991 Automatic with 52,500 miles in July of this year. It had an eratic idle surge also , every once and a while but not all the time. I took the car to Brookfield Acura in Wisconsin 4 days after I got it for a timming belt/water pump change and other 90,000 mile service. They told me the bad idle was because of dirty "Idle circuit". They cleaned the intake/idle stuff and it has been fine ever since. Brookfield told me to run the car hard every so often to clean the idle circuit out and it should be fine.

 

[brahtw8]

Re: Idle Speed

Brookfield told me to run the car hard every so often to clean the idle circuit out and it should be fine.

Are you saying that you were not running the car hard before?

You gotta wind her out every now and then, if not more frequently.

 

[wswen]

Idle

The previous owner might not of run it hard enough. My car was a one owner (doctor) who bought it new in 1991 and averaged only about 4500 miles a year. When I took the car to Brookfield Acura it didn't do the idle surging. After they changed the timing belt it did it again when they took it for a test drive. They where a little confused and it took them about a half a day to repair it. They told me they even talked to a technician in Japan about the problem. John Vassos said to run the car hard every so often to keep the Idle circuit clean.

 

[matteni]

A lot of people report that cleaning the throttle body helps out.

Here is my experience:

- Cleaned the throttle body, worked well for a while
- Problem returned
- Well oiled my aftermarket filter
- Problem returned
- Cleaned throttle body again, worked well but not as well as the first time
- replaced the plugs
- problem away

My guess? I believe that the problem was caused by the aftermarket filter and partly exasperated by the cleaning.

I believe that the oil from the filter was sucked into the intake and when I kept cleaning the throttle body I was basically contributing the fowling of the plugs by blowing all that oil and crud into the plugs.

Just a hypothesis but in the future I would consider the stock filter the next time and I will not purchase another aftermarket filter/with oil / etc.

Good luck with your idle problem. If you are not mechanically inclined I would take it to a reputable dealer.

 

[greyacura]

Another couple of things to check are:

1. Dirty Idle control valve ( this is separate from the throttle body, since at idle no air passes the throttle body, when you have problems just off-idle though, the throttle body is the likely cuplrit.)

2. Check your engine coolant sensor. Not your temp gauge sensor. This is key sensor for the Fuel Injection system. Sometimes they start behaving odd but not bad enough for the ECU to pick up as a fault.

 

[NoSeX4U]

Thanks for the advice, everyone. I'll follow the steps and let you know. BTW does anyone else experience a vibration @ 60mph (100 kph) that isn't there at 58 mph or 64 mph? It's weird...

 

[MarkB]

...My guess? I believe that the problem was caused by the aftermarket filter and partly exasperated by the cleaning....

Try exacerbated.