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99 Miata running rough with a P0301 code

My 99 Miata with 40k miles is running rough and I am getting a P0301 code (. I have tried simple things like new plugs and injector cleaner in my fuel, but neither helped.

-I am getting a spark at plug #1, however, if I pull the plug wire on #1 there is no noticable difference. If I pull the wire on #2 it stalls.

-Looking at the new plugs with about 20 minutes of running time, the #2, 3 and 4 plug have a darker dry residue. I guess that is what I would expect (with my minimum knowledge of engines). However, plug#1 is very clean and looks practically new. No discoloration or anything!

-Is it really firing? I think so. (agian, my limited knowlege in engines!)

-I decided to let it sit and run for another 10 minutes, but nothing changed. I can't really get down to the fuel injectors without moving what looks to be a lot of stuff, but I did look in the exhaust pipe and found black residue and a lot of moisture. It did not have much of a smell, but it was wet.

Just over a year ago I was having trouble starting the car, so Mazda replace the coil, plug wires, battery and the converter all under warranty.

Any ideas? Is there anything simple I can try before I take it into Mazda on Monday??

Thanks, Steve

Reply to
Steve
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Since I had nothing better to do on a beautiful Saturday morning, I swapped fuel injector #1 and #3. Wouldn't you know it, but now I am getting a P0303. It doesn't seem that any of the local parts store carry the injector in stock. Is Mazda the best place to get one? BTW, am I correct in assuming that the injector is bad?

Reply to
Steve

Steve,

Check to be sure that no wires are close enough to crossfire. I had the same problem after changing plugs and wires, and the problem disappeared when I used wire spacers to prevent crossfire (the new wires were slightly longer than the old wires, so they had a tendency to overlap or run close to the valve cover).

Sounds like plug 1 isn't firing all the time.

Mike Verive snipped-for-privacy@peoplepc.com

Reply to
Michael Verive

Are you periodically running an injector cleaner through your system?

Leon

Reply to
Leon van Dommelen

Mike,

I assume you are talking about the plug wires crossfiring. They are spaced out and setting in the spacerbar.

Thanks, Steve

Reply to
Steve

Leon,

I had not been using any injector cleaner on a regular basis. Maybe I should! Is that a common practice?

Thanks, Steve

Reply to
Steve

Leon,

I had not been using any injector cleaner on a regular basis. Maybe I should! Is that a common practice?

Thanks, Steve

Reply to
Steve

I do it, and it seems to me it improves how the engine runs, but I have no hard data. I would also think a lot of other people do it too.

In any case, at a relatively small sum and zero effort, (dump it in the tank), I just do it. Might be worthwhile trying, as I understand installing injectors to be somewhat of a pain.

Leon

Reply to
Leon van Dommelen

BK, thanks for the suggestion, but would you at least explain your reasoning for changing the plug wires?

Reply to
Steve

Just a thought, but if this was a good idea, would the top gasoline brands put it in their fuel? Always wondered how thoughs bubbles knew that they were to go to the injectors while the other soap suds were head for the sticking valves.

"J R"

Reply to
Ruxoid

Burned-on carbon may react different than injector deposits.

The price of the chemicals might also play a part, for all I know.

Leon

Reply to
Leon van Dommelen

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