Engine dies when letting off the throttle

[blk95lumina]

Hello.
I have a 98 Accord V-tech 4cyl w/ ~133K mi.
While in park or neutral, if I bring the engine up to ~3K RPMs, hold it for a minute and then let off the throttle, the engine revs down until it completely dies. The car then starts back up and idles just fine as if nothing is wrong.

When bringing the engine only up to ~2K RPMs and then letting off, the engine revs down until it is almost dead, sputters a bit, and then smooths out. The problem seems related to how much throttle you give it before letting off.

What could be causing the engine to die when letting off?

Thanks.

[danielsatur]

How doe's it idle, if you just start it up?

[blk95lumina]

Cold or warm it idles great. No shudders or hesitation.
I do not know the exact RPMs for cold vs warm as it is my GFs car, but if you think this is critical info. I can certainly get it.

Thanks.

[danielsatur]

The more acceleration, the more gas, air, and exhaust you need.
1) Replace the air and fuel filter
2) Have your catalytic converters converters checked, it could be causing the problem.
Only a blown cat with throw DTC's P0420 & P0430..

[jeffcoslacker]

So is there a driveability issue, or are you just playing? You know revving an unloaded motor is really not a good thing, yes?

Usually something mixture/vacuum related will cause this, stall on transition from rich to lean...something like a slow moving EGR valve that's making too lean when you drop the throttle, or an IACV that's not reacting fast enough to pick up the idle, something along those lines.

But if it doesn't do it when driving, I wouldn't sweat it.

[blk95lumina]

1) Replace the air and fuel filter
The air filter was replaced 5K mi ago and there is no replaceable fuel filter as far as I know on this model of the V-tech 4cyl. I have not been able to locate a replaceable fuel filter and the owner's manual and Hayne's manual do not list a replaceable fuel filter. This is the first car I have encountered without a replaceable fuel filter.
2) Have your catalytic converters converters checked, it could be causing the problem.
The catalytic converter was just changed about 1K mi ago but the problem existed before and still exists after. The DTC for a burned out cat was showing up before I replaced the cat but has not come back on after replacing.

So is there a driveability issue, or are you just playing?
No drive-ability issue as of yet. It has not died while driving.
Although a good test may be to rev it up down the road and let off.
I discovered the issue after cleaning the throttle body and running at 2K-3K RPMs to burn off the cleaner. I thought it was just residual cleaner causing the issue, but 3K mi later during the next oil change, I tested it out by holding the engine at 3K and letting off and the engine died....absolutely no cleaner used this time.

I was thinking an issue w/ the IACV as well but figured it would throw a code.

Thanks.

[blk95lumina]

Hello.
Anyone else have any ideas?
Thanks.

[somick]

It looks like you have covered almost everything.

What are the conditions of plugs, wires, distributor cap?

If those are OK, I woul check the aftermarket catalytic converter: Hondas do not like aftermarket stuff!

Good luck,

Sam

[blk95lumina]

Hello somick,
The plugs and wires were replaced 5K mi ago and the distributor cap and rotor were replaced 12K mi ago. Plugs and wires are factory Honda parts but the distributor and rotor are cheap aftermarket parts from Autozone.

As far as the cat, the issue was occurring before I replaced the cat and is still occurring after wards, so this leads me to think it is not the cat.

Thanks.

[snshddog]

I worked at honda and it sounds like the IAC to me. They can be sticky and slow responding and not set a code. They have to stop working all together to get a code.

[blk95lumina]

Hello snshddog,
Do you know of a safe way to clean the IAC?
Will throttle body cleaner harm it?
Thanks.

[danielsatur]

Clean both the IAC, and the throat of throttle body with cleaner.