Here's a question for you seasoned mechanics. Any ideas will be greatly appreciated. Here's the problem, a '96 Accord EX 2.2L VTEC with a slightly rough idle only when the engine is fully warmed up. Sometimes the idle roughness varies in severity. There's no hesitation or pinging on acceloration, so I assume it's not running lean and the fuel pump is doing it's job. I've checked for vacuum leaks with intake cleaner. I took off the EGR valve to see if it was stuck open, but it's not. I took off the throttle body and IAC to give them a good as new cleaning to no avail. I've replaced the rotor, cap, wires and plugs. Compression is good and vacuum is at 17inHg. I listened to the fuel injectors with a stethoscope and all 4 seem good and the tics sound the same. All sensor readings are good, I've even checked other Accord sensor readings to compare to mine. At idle the TP sensor is reading 12%, MAP sensor around 10 inHg, and the fuel trim -9%. I thought the TP sensor being 12% may make it rich, but I've seen other Accords even higher. The TP can't be adjusted anyway to compensate. The scanner is saying engine load is about 40%, which seems wierd, but I've seen another Accord at 35%. The engine is not misfiring, it seems to be more like an unbalence between cylinders. I've noticed what I thought was a good bit of rust in the fuel filter upon the 2nd round of replacing. My coworkers in the shop thought it was normal and I've seen worse myself with the engine running smooth as can be. The only thing I can see is that one of the injectors may be partially clogged. I've used the BG fuel additive and intake cleaner, but no differance. I'm thinking about sending the injectors to RC Engineering to be balenced and blue printed, but I wanted to see if anyone out there has any other ideas. Thanks in advance for the help.

 

Go to discount auto parts or any auto store...and have them test your alternator

 

once it warms up and starts missing, start pulling plug wires and see which cylinder is causing the miss.

 

Sometimes a bad TW sensor can give these symptoms. Frequently, the warm engine won't even start until it cools down.

When the TW sensor (Coolant Temp sensor) dies, it frequently dies "cold." That is, it tracks engine temp until it warms up, and then "goes cold" -- ie., it reports a cold engine to the ECU. This doesn't cause any problems as long as the engine IS cold. But when the engine warms up, the ECU thinks it's still cold, so it dumps extra fuel into the combution chambers.