When decelerating to a stop, my motor sometimes quits after I come to a stop or when slowing for a low speed turn. Sometimes it doesn't stop, the idle just drops down to 4-500 rpm and idles rough and then will return to the normal 800-1000 rpm idle. The conditions are always the same: clutch in - decelerating. MAP voltages are good - 1 volt or less. If I rev the engine while stopped, the injectors cut out and come back on line at the right time - the idle will initially stabilize at 1000 rpm, then slowly idle down to the normal 800 rpm. It's only when decelerating or when maneuvering at low speed (like around a parking lot) that the motor quits after depressing the clutch. All the normal items that affect idle work properly, the brake lights, air conditioner and running lights, it just sometimes stalls when coming to a stop or coasting with the clutch depressed. It's not the gas, it's been doing this for 5 tanks and I've used every additive known to man. I don't think it's a leaking injector because the idle is smooth when the engine is idling at the right rpm. I replaced the air filter. The Honda techs are perplexed.

Help...

 

It's partially to do with the car's ECU trying to compensate for sudden "off throttle" rpm decline and your driving style. You appear to be the type that coasts a lot with the clutch in. You should have the clutch out as much as possible. When coming to a stop, leave the clutch alone till your rpms get to about idle speed, then push it in. If you going around a slow corner, leave the clutch out. If you negotiate the corner that slow, downshift to 1st and then leave the clutch out while going around the corner.
Part of the problem is you revving it when the rpm gets too low. The ECU is trying hard to learn to keep the idle speed. Altering the rpm (throttle position) at this critical moment will either delay this "learning" or make it impossible.
From what rpm do you usually de-clutch? If it's too high, this will also have some affect on the ECU on how it learns. Of course, this can all be aggravated by hot engine bay temps and by the use of the A/C (more parasitic drag on the motor at low rpm). However, even with the A/C on, ultimately the ECU can learn to compensate if your driving style and habits don't interfere.
All of the above is contingent upon your car being up to date on maintenance such as air filter, good gas, good plugs, good working injectors, proper adjustment on the throttle cable. If any of these are not up to snuff, you're fighting an uphill battle.

 

not sure if this will help, but my Civic SI does the exact same thing, but before it turns off most of the time a Check Engine Light comes on and goes away with the next start. I pulled the code and it seemed like I had a bad TPS sensor.

 

Take your car to a mech and check if the screws on the throttle position sensor (left side of the throttle body) are ok. If they're loose, it would do this kind of a thing. NEVER take the sensor out.

Do you have any mods on the car? if you have an engine management controller like Greddy E-Manage or Apexi PowerFC, there would be a false setting.

Another thing, if the TPS is ok, reset your ECU, turn on the car and let it run for 15 mins. Than drive the car and see what happens.

 

NorthCyprus: I think you are addressing my problem and to answer your question best you may want to check this thread out:
http://honda-tech.com/zerothread?id=1369274

After unplugging my TPS sensor and replugging it, I reset the Cel and since then have driven it for about 20 miles or so w/o any issues. I haven't pushed the car hard yet, so who knows if the problem went away (doubt I'm that lucky), but will keep both post updated.

Thanks and sorry for hi-jacking your thread

 

Thanks for your response. While I admit my driving habits may not be the best, I have driven a stick all my life, been to a couple of competitive driving courses and participated in a variety of competitive events, so I think I use the clutch in a more or less normal way. Most importantly, my driving habits didn't affect the Honda's idle for the first 29,000 miles I've driven it. It's only been doing this goofy idle thing for the last 900 miles.

I did the idle learning procedure and it didn't help.

Do you think it could be the Inlet Air Control Solenoid?

Thanks

 

OK, I'll have my tech check out the TPS.

This car is box stock.

Thanks

 

Most certainly, it can be a mechanical issue with the car. Sensors and parts get old and don't function in the same way. Of course this can result in it not quite being able to compensate for driver technique anymore (and I'm not saying this is the case here, just a hypothetical scenario).
Other than the maintenance topic I mentioned, yes, your MAP sensor could be going a bit odd. There's a TSB out for bad MAP sensor performance that involves a better securing system for the harness. Your car may be in this catagory. You can test this one by pulling off the wiring harness and wiggling it back on to "freshen up" the contacts and maybe use some strong tape to temporarily hold the harness tight. If this solves your problem for the time being, you may have your answer. Also, in conjunction with this, reset the ECU by pulling the "BACK UP" fuse for 1/2 minute.
Also, the Idle Air Control mechanism could be having some difficulties. If you can eliminate the other stuff I wrote about, then proceed to target these.

 

I changed my plugs and gapped them on the wide side and got the same problems that went away when I regapped the plugs.

How old are your plugs?