Throttle drop almost to stall during coasting?

[hofffam]

On my 97 NA2, the RPMs drop below 500 rpm, almost to the point of stalling, then recovers when I let off the gas when I am coasting to a stop. It seems to be worse recently.

Based on searches here, this is controlled electronically on my NSX, not by a damper device. Some posts seem to say a throttle body cleaning will help or cure the problem. The car idles runs terrific otherwise.

What should I be looking at or doing to correct this?

 

[shawn110975]

yes your throttlebody needs cleaning or there is a vacuum leak.
somewhere.

open hood and feel your air hoses tug on them a little see if you can hear a leak. if they all feel strong and or no leaks then proceed to clean the throttle body.

my way is have someone in the car since its a 97 throttle by wire system
take air box off so you can see the choke plate have them rev it and spray carb&choke cleaner into the air intake all over, the car will try and stall, thats why your partner is reving it to keep it from stalling.
do this multiple times use the whole can. then let idle should be good.

there are otehr ways like take it apart etc. but this works for me on all kinds of hondas

good luck

 

[Honcho]

Yep Shawn is right- sounds like a dirty TB. Also, when the car is off, disconnect the four vacuum hoses on top of the TB (one at a time so you don't mix them up) and give each port on the TB a good shot of carb cleaner. It will drip down into the TB, so make sure to wipe it out with a rag.

 

[shawn110975]

+100 agree with Honcho

 

[hofffam]

Yep Shawn is right- sounds like a dirty TB. Also, when the car is off, disconnect the four vacuum hoses on top of the TB (one at a time so you don't mix them up) and give each port on the TB a good shot of carb cleaner. It will drip down into the TB, so make sure to wipe it out with a rag.

Are these four hoses small and right next to each other?

 

[EAC]

I have the same problem. I've cleaned it numerous times with no luck. I only sprayed the inside and wiped it out though. I never squirted it inside the ports or did it while running the car.

Hmm..

 

[jorligan]

Make sure you also squirt into the idle air passages (see the DIY write up in NSXDRIVER) I had the same issue and although it didn't seem to be dirty, cleaned it and no more issues. This is in a heavily modified turbo car using the SOS modified AEM and a lightened flywheel.

 

[EAC]

Make sure you also squirt into the idle air passages (see the DIY write up in NSXDRIVER) I had the same issue and although it didn't seem to be dirty, cleaned it and no more issues. This is in a heavily modified turbo car using the SOS modified AEM and a lightened flywheel.

I've searched and searched. That article is impossible to find.

 

[Larry Bastanza]

Make sure you also squirt into the idle air passages (see the DIY write up in NSXDRIVER) I had the same issue and although it didn't seem to be dirty, cleaned it and no more issues. This is in a heavily modified turbo car using the SOS modified AEM and a lightened flywheel.

That is exactly the problem. Cleaning out the bore does nothing, the idle passage is clogged. We just did a DIY special NSXDriver issue with this article included, I know, I wrote it.

In fact my first example in the article is a 1995, which is the same as the 1997. Contact NSXCA and purchase a back issue. I will warn you though, very expensive, about $5.00!!!!!!!!!! Or better yet become a member of NSXCA.....

HTH,
LarryB

 

[DRBROOKSZ]

I had same problem---tb cleaning solved prob. MY CAR IS 2003--RUNS GREAT

 

[hofffam]

Like many here I could not find a copy of the NSXDriver article.

So I cleaned the TB as follows:

1. removed the air filter box
2. removed the rubber bellows between the TB and the airbox
3. propped the TB butterfly open with the fat end of a screwdriver
4. sprayed Gumout carb cleaner in the TB
5. removed each of the four vacuum lines on top and sprayed cleaner into each of the four fittings on the TB
6. waited; then wiped the inside of the TB with a rag as far as I could reach
7. Started the car; it ran like complete crap at first. CEL light was on.
8. Kept the engine running. Had to use the throttle to keep it alive.
9. Shut the engine off. Removed the clock fuse to reset the CEL.

The next start had a stable idle. When revved, then let up, the idle dropped smoothly to 850 rpm. Never dipped near 500 rpm or below like it did. Drove the car and glided to a stop as I sometimes do - and the idle was perfect. Very happy with the results.

 

[Honcho]

Glad to hear it worked out.