1998 Honda Accord

Mileage: 210,000+ miles

Primary Issue: Random engine stalling, predominantly at lower RPMs (below 1.5k RPM) during slower driving or idling. The stalling has not happened while highway driving.
-Recent Maintenance

1. Replaced the fuel pump and strainer. Previously the car required 5 key turns when cold to start, now starts with 1 key turn, so it fixed that.

-Symptom Overview

Engine Stalling Characteristics:

1. Gradual engine shut down with RPMs decreasing over 1-3 seconds.
2. No prior noises or changes in engine performance before the stalling.
3. Restarting immediately after stalling results in the engine starting but stalling again within a few seconds.
4. Waiting 30 seconds to 2 minutes before restarting allows the engine to run normally until the next stall.

Engine Performance:

1. No loss of power; performs well under load and at high speeds.
2. Fuel efficiency is reduced (16 mpg) compared to expected (23 mpg).

Diagnostic Checks:

1. No dashboard warning lights or diagnostic trouble codes.
2. Fuel pressure test indicates normal pressure readings (42-48 psi).

Temperature and Environmental Conditions:

1. Stalling occurs at various engine temperatures and is not influenced by environmental conditions.

Exhaust and Odor:

1. No fuel smell detected from the engine bay.
2. Normal appearance of exhaust smoke; slight exhaust leak present.

Spark Plugs:

1. In good condition.
   

IACV Status:

1. Cleaned a few months ago with no noticeable change in idle quality. Cleaned again this week using a full bottle of carb cleaner, the car still vibrates the same, and still stalls.
2. The IACV wire shows good voltage.
3. Persistent idle roughness and vibrations, exacerbated when the AC is on or during cold starts. This condition has been present since before the stalling issues.

Recent Driving Observations:

1. During a 50-minute drive (30 minutes in stop-and-go traffic and 10 minutes at highway speeds), no stalling occurred.
2. Stable RPMs during driving, RPMs are also stable while idling with no input. but I noticed while driving that if i revved the car to 2 rpm, and then let off the cars gas, the cars rpm would often drop to an amount like 100-200 rpm above its normal idle on the gauge for around 2-3 seconds, before dropping to its normal idle without input. (OBD2 scanner says 700-750 rpm idle without input. so what i'm saying is when i revved engine to 2000 rpm, and then took foot off the pedal, it'd drop to what would look like 900 rpm on the gauge for like 2-3 seconds, before dropping to the 700-750 again.)
3. Creeping speed felt weak sometimes despite the OBD2 scanner showing normal idle RPM (around 700).
   Car stalled while reversing into a parking spot: RPMs gradually stuttered down to zero over approximately 3 seconds. Immediate restart attempts led to a quick stall, but waiting a minute allowed the engine to start and run normally.
4. Activating the power steering pump (by turning the steering wheel) temporarily increased RPMs and improved creeping power.

Important Symptoms

1. The engine does not shut off immediately; instead, the RPMs gradually decrease with noticeable jerking until complete stall.
2. Dashboard lights remain functional during stalling.
3. Immediate restart attempts after stalling lead to a quick stall. In contrast, waiting briefly (30 seconds to a minute) allows the engine to start and run until the next stall.
4. On letting off the gas quickly, the RPM went down, but instead of going to its idle amount, it dropped near 0, almost stalling, then recovered to the idle amount. This only happened twice, it doesn't happen often / all the time. The reason why I mentioned this is because the stalling is so random, sometimes driving 40 minutes with no stall, and sometimes stalling 4 minutes after startup. so it having happened twice, means it might be more than just a coincidence.

 

I have the exact same issues with my 2000 Accord 2.3; I've replaced fuel pump, ignition electrical connector (common symptom), evap canister was replaced previously, new injectors, etc. It ran fine the day I replaced fuel pump and then symptoms started again randomly...ran fine after fuel injectors installed, then no start now after a day of driving it - main relay has been replaced, fuses are good to go, just have to check fuel pressure (maybe fuel pump is bad even though new (<two months)....not sure what else? If you get a fix, please share.

 

Good idea to check your O2 sensor(s) (Oxygen Sensor) if never been replaced. Those don't always place a trouble code in the computer; at least mine didn't, but mine is an OBD-1 computer. Anyway, that sensor is a part that should be replaced anyway after a lot of miles. Better running, better gas mileage. For these Hondas, Denso O2 sensor is the best choice.

 

My 1994 Honda Accord EX had a similar issue recently, many of the same symptoms. It was my MAP sensor. Maybe take a look at that? I pulled a couple from a local salvage yard and tested them out and it runs right as rain.