Jhastings

I have a 2004 rx8 6 speed it will run but runs really rough backfires real bad and have to Rev to 4k rpms to drive at all I have replaced coils wires and plugs I don't know how to test if coil packs are getting signal or not I checked with timing light trailing plugs are sparking but nothing on leading at all any advice would be greatly appreciated

Loki

iTrader: (1)

Have you wired them correctly? Right coil to right spark plug?

At idle the trailing may not fire, but if you've gotten the connections reversed, only trailing would fire.

If it's not that try moving a trailing coil to a leading position and see if the problem travels with the coil.

Jhastings

Even if it revs up leading does not spark at all was going to switch around coils and see if they get spark that way and yes they're hooked up correctly
let me rephrase that guy that I bought it from had same problem I replaced coils wires and plugs is it possible that he done the connectors in wrong coils if he replaced them? What would happen if i change the electrical connections and they were right would it still run or would it mess up engine?

Loki

iTrader: (1)

Totally possible he messed up the coil wiring. It's hard to do with stock coils but if they're aftermarket with extra adapter wires then anything is possible. Get a wiring diagram and go over everything by wire colour to make sure it's all hooked up correctly. It only works one way.
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Loki

iTrader: (1)

In what condition were the spark plugs you took out?

Jhastings

The plugs I took out still looked fairly new I went ahead and replaced because I knew it was something in ignition where it was backfiring under acceleration and where would I find a wiring diagram

Loki

iTrader: (1)

Wiring diagrams https://gprivate.com/66vvo

Has the engine been changed recently? If so it's also possible someone reversed the fuel injectors wiring, it's very easy to do.

Jhastings

I changed the coils around and still only getting fire on trailing plugs the wiring harness is in correct order the plug wires are correctly installed and how would fuel injectors cause the leading plugs to not fire? I'm a newbie to rotarys sorry for all questions

Loki

iTrader: (1)

You're right, injectors won't cause the plugs to not fire, but they can cause the same symptoms otherwise. So if it's not the coils, and everything downstream from them is new and correct, my only thought is try resetting the NVRAM. Key to On, rapidly pump the brake pedal 20 times. You should see the oil pressure gauge sweep if done right.

When you say leading plugs, you mean the 2 lower plugs as seen through the wheel well, correct?

Jhastings

Yes I have done the brake 20 times and oil gauge goes up halfway and back down that did not fix it that was one of the first things I tried and i also replaced ess also and yes the bottom 2 plugs. Also what would happen if I change the trailing plug wires to leading would that hurt the engine?

Loki

iTrader: (1)

You mean wire the leading plugs to trailing coils?
Yes that can damage the engine if driven for any length of time. I suppose you could do it for a test though.

Jhastings

Okay also how do I go about testing if I have power coming to coil through factory harness

Loki

iTrader: (1)

Whelp I was wrong. It idles on trailing plugs, not leading. So nothing to fix here. You can confirm with an HEI tester that all 4 indeed fire at startup.

As for the poor driveability, back to the first question: was the engine changed and if so, are the primary injectors connected correctly? Easy mistake to make when installing engines and leads to issues like this. Also some people have managed to install the wrong injectors in the wrong positions.