Low Idle problem

bling

bling

Experienced Member
Joined
14 April 2004
Messages
456
Location
Houston / NYC / Tokyo
My NSX is having quite a few problems recently. About 3 weeks ago, I had an CEL and it turns out Cylinder #1 & #2 misfire. In addition, idle was very low and my car stalled when coming to a stop.

My mechanic looked into the problem and fixed the wiring that caused the misfire and have my clutch replaced with a new aftermarket unit.

However, the idle is still low (4-500 rpm) and will stall coming to stop. He switched out the throttle body to test out the problem. The car idle just fine when he has a new unit on. When he put the original throttle body back on, the idle is low again. He recommend me to get a new unit.

Should I get a new unit or should I try adjusting the idle with the existing throttle body? Please advise.

I really miss my car :frown:
 
Thanks a lot, Ojas. I will check and see if I can adjust that tonight...BTW, nice avatar :biggrin: I want one of those stickers :tongue:
 
I do not know if it has been done, but a complete Throttle Body cleaning will do wonders, especially for the TBW cars which have a unique idle feed system:).

See the last issue of NSXDriver for my tech writeup on performing this service.

HTH,
LarryB
 
Now that I have my car back and talked to my mechanic, I have a better idea of the problem:

When starting the car cold, the idle is perfectly fine at ~800 - 1K rpm. However, after running for a while as the engine get hot with max AC in Texas weather, when I slow down the car, the idle will drop all the way to 0 and then the car just die. Even if it remains running, when I stop, the idle is just yo-yoing between 200 to 500 rpm with some unpleasant growling sound.

He was saying this might have to do with the electrical part of the throttle body. What should I do?

Larry, I just joined NSXCA and I do not have the writeup you're talking about. Anyone care to point me to the right direction?

Thanks in advance.
 
After cleaning the throttle body with the TB cleaner, the idle improved, but still fluctuating. Would that problem relates to the EACV?

I have a 95 but my service only has a diagram for a 91. Could someone post a pic showing the location of the EACV on a 95 throttle body?

Thanks in advance.
 
Just ran out and took a couple pictures of the throttle body and would like someone to confirm a few things for me.

9987TB_1-med.JPG


picture #1:
- Is the nut in the red circle for idle adjustment?
- Is the unit in yellow circle the TB sensor?

9987TB_2-med.JPG


picture #2
- Is the unit in yellow circle the TB motor or EACV?
- By disconnecting the wiring shown by the red arrow, will I be able to adjust the idle by turning the nut in picture #1?

If that item is NOT the EACV, where would it be and how could I diconnect the wiring?

Thanks you very much in advance.
 
You don't have an EACV. On TBW cars, the throttle servo motor controls the idle in responce to ecu command by opening or closing the throttle plate, the same way an EACV does it when the plunger moves to open or restrict its orifice. Larry is most likely correct, especially as some cleaning made some improvement. On TBW, 'throttle cleaning' is sort of a misnomer. What really needs cleaned are the six small air hole at the base of the manifold. Good news is these ARE cleaned when you run cleaner thru the t-body, because some cleaner gets into these holes. Try this- remove the fat hose on top of the t-body, the one facing the engine, that goes to the T. Spray ALOT of cleaner into this hose, let it soak for about ten minutes, then start engine and clean thru the body SLOWLY. Remember that squirting liguid, or even to much spray at once, can cause engine damage.

In pic one, red is circling the ide screw, but you should never have to adjust this. Yellow is circling the TPS. In pic 2, the throttle motor is circled.

HTH,
MB
 
Little addendum: In pic No. 1 a bit right of the red circle you see a small double nut with yellow seal colour. This one is the idle bypass adjust screw AFAIR - details are here - solved at least my former idle problem.
 
BIG Addendum :eek: Never, Ever, touch that little screw with the yellow paint on it. Its set at the correct throttle valve (butterfly) to throttle bore clearance and is very critical. This spec has two critical purposes- one is the mechanical fit that controls things like wear, and never sticking (among other things) and two, is the more obvious idle air flow quantity. As I mentioned, it is VERY rare to ever have to adjust idle, but if needed the screw circled in yellow in pic one is there for that purpose. According to Acura, if you ever touch that screw, throw the throttle body away. IF there was a published spec for that clearance, it could be set with a feeler guage, but there isn't, so you can't. :rolleyes:

As a very good general rule, any part with yellow wax paint glopped on it, should never be touched.

MB
 
NSXTech said:
Try this- remove the fat hose on top of the t-body, the one facing the engine, that goes to the T. Spray ALOT of cleaner into this hose, let it soak for about ten minutes, then start engine and clean thru the body SLOWLY. Remember that squirting liguid, or even to much spray at once, can cause engine damage.
Click to expand...


Quick clarification before I proceed on this...the hose you mentioned is the one w/ the blue arrow, right? Which side should I disconnect and where should I spray the cleaner? Please give me some further details.

BTW, after cleaning the TB since couple days back, my idle improve significantly with only a little fluctuation every now and then. However, I do want to fix the problem once and for all...

Thanks for everyone's help! :smile:


9987TB_2a.JPG
 
NSXTech said:
BIG Addendum :eek: Never, Ever, touch that little screw with the yellow paint on it. Its set at the correct throttle valve (butterfly) to throttle bore clearance and is very critical. According to Acura, if you ever touch that screw, throw the throttle body away.
Click to expand...
Mmhh - we "touched" that screw a few times - meaning we solved the bad idle behaviour some time ago (unstable base idle and cutting off the engine when braking hard at the track) by adjusting it but we didn't throw the TB away afterwards. Could our behaviour have lead to some other problems (you know my long "overheating at the track" thread?).
 
NSX-Racer said:
Mmhh - we "touched" that screw a few times - meaning we solved the bad idle behaviour some time ago (unstable base idle and cutting off the engine when braking hard at the track) by adjusting it but we didn't throw the TB away afterwards. Could our behaviour have lead to some other problems (you know my long "overheating at the track" thread?).
Click to expand...

There is no way I can think of where the two are related. The throw away message I got at NSXTraining was that the throttle plate adjustment is so critical to drivability and to some extnt emmisions, that if it has been moved, and there is no spec to restore it, well then there are no options but to pitch. I admit this is radical- I would have options. I always have enough NSX's in the shop and t-bodys left over from used engine installs, that I would take comparative measurements and adjust one accordingly. That said, I would do so only after advising the owner that the reccomended procedure is replace, but the options are the following.

I have a sincere reverance for the yellow wax paint. I went to my first Honda CVCC carburator school in 1978. There was (is) a small screw with the yellow on it that set the opening angle for venturi #3 in relationship to V1, and if it was touched, there was no way to restore it (technically) We were told to throw those away too. Problem is, the yellow paint calls to you, like, "yo- down here' and less informed people go for it. We had a lot of cars towed in
in those days after some hack tried to adjust someones idle.

Cheers,
MB
 
NSXTech said:
Try this- remove the fat hose on top of the t-body, the one facing the engine, that goes to the T. Spray ALOT of cleaner into this hose, let it soak for about ten minutes, then start engine and clean thru the body SLOWLY. Remember that squirting liguid, or even to much spray at once, can cause engine damage.
Click to expand...

I did just that today; however, the idle is still fluctuating with A/C on at full power. It appears that without A/C on, everything is working fine.

In addition, even w/ A/C off, when I slow down the car and release the clutch, the rpm will go all the way to 0 and then rebound back to approximately 500 - 700 rpm.

My mechanic told me this should be due to the electronic component of the TB and recommend me to get a new unit to replace my existing one. Should I take this route?

Please help!
 
Wow Bling i'm having the EXACT same problem that you are having. I had the problem both with the AC on and off, but after I cleaned the TB it eliminated the problem as it did for you.

I still have the problem with the A/C on, that I get a serious fluctuation in idle and at times the car wants to stall. I've also noticed the same at hard braking.... so I'm in the same boat as you. I was ready to post a new topic when I saw your former post... After reading it i've realized i've got the same EXACT problem.

Anyone have any more ideas?? Or Bling have you heard anything???

thanks!!!

I've also wondered if it had something to do w. the electrics in the throttle body... :confused: :redface:
 
Are the spark plugs okay? When I had the low idle problem, first the mechanic adjusted the idle controller but he also said to replace if can. Then the problem persist and turn out the coils are bad so I had them replaced at the same time bought new sparks plugs as well. Problem solved for a while then CEL lights came out and I had to replace the O2 sensors. Bad O2 sensors made fuel running rich and the plugs got a lot of carbon on it. How many weeks now since O2 installed and the car is running great. :smile:
 
actually in my case... i have brand new plugs, coil packs, and 02s and I still have the problem...
 
nsxot1c said:
Wow Bling i'm having the EXACT same problem that you are having. I had the problem both with the AC on and off, but after I cleaned the TB it eliminated the problem as it did for you.

I still have the problem with the A/C on, that I get a serious fluctuation in idle and at times the car wants to stall. I've also noticed the same at hard braking.... so I'm in the same boat as you. I was ready to post a new topic when I saw your former post... After reading it i've realized i've got the same EXACT problem.

Anyone have any more ideas?? Or Bling have you heard anything???

thanks!!!

I've also wondered if it had something to do w. the electrics in the throttle body... :confused: :redface:
Click to expand...


I never really checked back to this thread.... :tongue:

My problem is gone now that I have a new mechanic. He noticed one of the spark plugs was not properly gapped (leaving a gap MUCH smaller than it should be), therefore, my car was firing at only 5 cylinders :eek: . My guess is that my old mechanic MIGHT have dropped it on the floor or something :rolleyes:

Once that's taken care of, I have absolutely NO problem with AC on at full power under the Texas sun :cool: .

You might want to check into that although you have new plugs...to see if they're gapped at the right width.
 
If you use the factory plugs, DO NOT gap in the conventional way. The tiny platinum tip will chip its coating at the slightest provacation. NGK says never use a gapping tool and this is not a false warning. If the gap has changed thru use, they are worn out. If a new one is slightly off, you can use a side electrode bending tool that never touches the center electrode.

MB
 
Hi guys,

I have been experiencing a similar low idle issue when coming to a stop and letting of the clutch. I'm looking to clean my TB and have seen the NSXdriver article mentioned in several threads. I'm however not having much luck searching for the actual procedure to clean the TB on an OBD2 car.

I assume it's fairly similar to any other TB cleaning, however I'm not sure on how to properly clean the throttle plate on a TBW car and want to make sure I get the proper hose mentioned by LarryB

Does any have the detailed procedure listed anywhere or can give me a quick rundown? Alternately is it possible to get a copy of the NSXdriver article, I assume not given it's age.

Regards,
 

Similar threads

DRIFTER
TPS orientation?
Replies
2
Views
216
DRIFTER
DRIFTER
I
98 NSX-T Starts, idles but won't drive. CEL Multiple misfires due to fuel system malfunction.
Replies
1
Views
395
Old Guy
Old Guy
S
Rev and idle issues after a long rest
Replies
10
Views
213
Old Guy
Old Guy
Fabunoz
Is this normal IDLE RPM or too low?
Replies
13
Views
688
Wild Turkey
Wild Turkey
A
1991 NSX just doesnt want to run right/pass smog...
Replies
24
Views
2K
Honcho
Honcho
Back
Top