'99 Accord 4cyl LX - Engine dies from high RPM drop

[mechatronic]

Bought the accord used with ~170K miles, now has 186k miles. 2.3L F23A1 engine w/ a 5 speed manual transmission.

The problem shows up after the engine warms up and driven on freeway for 15 to 20 minutes. When the clutch is pushed in, with engine above 1500 rpm, the rpm will drop below the normal idle rpm (~700rpm) to around 500- rpm, the ECM will try to increase the engine rpm, but most of the time will not make it and engine dies. Engine will restart right away. Sometimes engine dies on the freeway when car hits a slowdown on the freeway. Dangerous.

Attempted fixes:
1. Replaced the IAC valve
2. Cleaned the throttle body plate and inside housing
3. Insured the coolant system is well bled of air
4. Recent Cap, rotor, and plugs changed
5. Thermostat changed

The Actron scanner shows the TPS starts at 9.8% and increases as the gas pedal is pushed down - very consistent. The MAP sensor is showing 100 Mpa when engine is not running, and showing ~24 when running.
Couldn't check the fuel pump pressure b/c the set bought from Pepboy did not have the right adapter.

Any input would be greatly appreciated.

[mpumas]

Have you done a smog check? How is the NO2? You could also do a EGR test which will show if the EGR ports are clogged and if the EGR valve is functioning normally.

[mechatronic]

The car is due for a smog check this month, so it'll be tested soon.

Performed the EGR test according to the Haynes manual. Passed.

EGR test Details:
1. Measured between 1 and 2 > 1.35 kohms
2. Measured between 1 and 3 > 3.89 kohms
3. Measured between 4 and 6 > 7.7 ohms
4. Warmed engine up til electric fans came on. Applied current (w/ 3A fuse) to pin 4 and pin 6 grounded > engine dies (and it's suppose to).

I read at another forum that the Ignition Control Module can be cutting out after heating up and should be changed at 120k miles?

[mechatronic]

Just got the smog check and passed.

NO (Nitric Oxide) Results
________Max___Ave___Measured
15 mph---443----57----0
25 mph---730----50----0

[somick]

This generation is not known for problems with the main relay, but everything is possible since the problems start after warm up. It looks like you covered almost everything but fuel system.

Keep us informed and good luck,

Sam

[mechatronic]

After driving the car for half an hour to heat up the engine, and used the Actron Scanning tool to collect data while raising the rpm over 2k and letting go of the gas pedal repeatedly.
Transferred the data to my PC and graphed the results in Excel.


The blue line shows the rpm, and the red line is the ignition advance.
Graph showing when the engine dies, the ignition advance was retarding too much.
I've got a hunch the Ignition Control Module is acting up when it gets hot. Got a new distributor on ebay. Installed it and no more idle dropping and engine cutting out.