Surging Idle

[goldwing2000]

Anybody have a problem with surging idle while coasting to a stop?(Mazda3 only, please)

It's just started doing this recently, like within the past month. Manual trans, 2.3L eng, drives fine,idles normally while stopped but if I'm cruising along at any speed and I push in the clutch (like approaching a red light), the idle will drop to almost stall then will recover to about 1,000 rpm and bounce like that until the vehicle comes to a stop.

The tech at the dealer said they were having similar issues with the RX8 and a faulty ECM flash was the prolem.

(scratch)

 

[wongpres]

Yes, a co-worker of mine had this problem (Mazda3 2.0l manual). About two weeks after the surging idle started, the CEL came on, so he took it to the dealer.

This TSB was utilized to identify & fix the problem:

MIL ON - P0442/P0455/P0456
Applicable Models
Model Starting S/N Ending S/N
2004 MAZDA3 00000000 ZZZZZZZZ

Some vehicles may exhibit a MIL ON condition with DTCs P0442, P0455, and/or P0456 stored in memory. See the following list for possible causes.
Capture freeze frame data, then clear all DTCs. Run the WDS evaporative system test to confirm the leak. If vehicle fails, use the Mazda approved, EVAP Tester (Model #134-01049) to further diagnose. Activate Mode 8 to manually close the Change Over Valve (COV). Note that the purge solenoid valve is Normally Closed. Run the gas leak test and the smoke test to confirm leak location.

On Mazda3, the following conditions have been found:

STUCK OPEN PURGE SOLENOID VALVE - Confirm by removing purge solenoid control valve hose at the intake manifold, then inspect to see if smoke exits from the hose. If smoke is seen, this indicates a valve that is stuck open.
Note: If hose is not removed, smoke may not be seen anywhere, and it will appear the vehicle has no leak.

MISSING "BASKET" SEAL - A smoke test will reveal if a basket seal is missing from a quick disconnect fitting.

--

The "STUCK OPEN PURGE SOLENOID VALVE" condition happened on my co-worker's car, so they replaced the solenoid valve and the CEL and surging idle have since been remedied (took it to the dealer just after Christmas).