deetz

when i let her sit at 700 rpm at idle she misses. its not a total miss but u can watch the rpm guage go down the up its a soft miss. ive replaced the plugs like 400 miles ago long with the wires,, just started it today while i was in traffic.. any ideas and DONT tell me it lost compression. lol

deetz

not to sound impatient lol anyone have any idears??

scathcart

Its a rotary.
They do that.

VaGambler

iTrader: (1)

I'd check my vacume lines

homebrewer

Replace your plugs and wires if you haven't recently. The excuse that they all do that is baloney. Mine does it after about 10,000 on the plugs. With new plugs it doesn't miss at all at idle.

scathcart

All periphereal port exhaust rotaries will have a bit of a miss during idle; one of the effects of overlap.
New Mazda remans with 120 psi on all faces, new injectors, perfectly set TPS, stock exhaust... Basically as the car rolled off the assembly line... the miss will still be there. Whether or not you're observant enough to pick it up is one thing, especially with the extremely quiet stock exhaust on, but hook up the right diagnostics, and you'll see it.

Now then... the more you modify the engine, the more pronounced the miss will get... especially when you port the engine.

Keeping the car in proper tune helps, but even with that all in order, it'll still miss.

The best thing to help with the miss is to change out the stock ECU... to pretty much anything else. The first thing everyone always notices after an EMS install and tune is how much better the car idles.

RETed

Geez...47 minutes...

If you're running stock ignition system, it's normal.
Someone o-scope'd the ignition, and it misfires every 4th or 5th spark.
It's due to the dual-tower leading coil.


-Ted

deetz

it only does it when ive been driving the car for a long period of time...


ted- thanks for pointing that out lol