Started happening a lot more often lately, but sometimes when I'm just sitting at a light, sitting in neutral, I'll see the RPMs start to drop towards 3 ticks below 1,000 (usually sits 1 tick below 1,000), the car will start to shudder and shake and feel on the brink of stalling out. Then suddenly it'll rev up to 2,000 and slowly go back back to 1 tick below 1,000, and if I let it sit some more, it'll start dipping to 3 ticks below, and do the whole thing over again.

This is with the A/C on and off, and I'm not pressing any of the pedals, just chillin at a light idling.

I know when the compressor kicks on, the RPM will drop a bit, but this is a significant amount more than that, and even when the A/C is off it'll do it.

If I tap the gas, it'll rev up, but if I let it sit, it'll start doing it again. It doesn't happen each time I come to an idle, only every so often.

Any ideas?


I've gotten an oil change and new plugs/wires about 2,000 miles ago (~2-3 months ago)

 

You put 20w-50 engine oil it it? Seems awfully thick to me.Just an observation, not sure that it would impact this issue.

 

The latest oil change was 5w30, so should be fine

 

Need more info on the car. How many miles? Any mods?

 

unplug the battery for a reset
usually when my engine starts to idle rough, it means its time for some red lines. works every time.

 

40k, no mods

It's been doing it for about 7 months and I've reset it a few times when plugging in some stuff to the battery for testing a carPC build.

It's not idling rough, it just dips every so often and almost stalls out, other times it'll idle just fine for extended periods of time.

 

upgrade the wiring from your engine to the ground to 2gauge or 0 gauge wiring should stop that issue

 

thats because you're in Washington- he's in Florida. it is too heavy for you- but not too heavy for him for half the year or more

 

dark check the neutral switch on the tranny.

Look at Jon316 posts or mine with neutral switch key words for testing procedure etc

 

Here is what Zoom is referring to:
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-test-neutral-reverse-switch-200453/

 

Thank you, I'll take a look

Yea, I run 20w50 during the hot season (3/4 of the year) and switch back to 5w30 for the "winter" season which is around this time till January/February

I'll take a look at this as well


Thanks guys

 

S2 has different Gearbox switches, same principal..

Grounds were updated in S2.

What is your Air Filter like??

You are in Florida, warm climate, lots of dust..I am guessing..

I would also check and clean MAF Sensor..

 

What's your driving style?
Great suggestions so far...
All I can add is a seafoam cleaning of the engine.

Edit: deleted off topic reference

So many things to check... Good luck

 

/\ Lets not starts this Oil BS here...What a load of Crap..

My Mazda (Japan) printed S2 Owners Manual says that THICK oil 20W50 Can be Used, so stop preaching this rubbish...Please..

I have never heard so much Bullshit Talked about oil...

The RENESIS core Engines are the SAME Parts all over the World...there is NOTHING special about the US or ANY other country for that matter..

 

I haven't checked it, did get a new one put in a few months ago, I'll take a look in the morning before work.

 

OMG Don't tell them that!

I removed the reference.

 

Late reply I know.. shame on me.. anyways, I checked the filter, wasn't too dirty, but I'll be replacing it soon just in case.

However.. new problem now, I have significant difficulty starting in the morning and it's getting progressively worse. It started as 1 or 2 extra turnovers, and this morning it had to turnover a good 7 times and it took 3 attempts to get to start.

I'm going to guess it my plugs/coils..

 

Not using any Coolant?

You still have warranty?, I would take it to a Good Mazda Dealer..

But not liking the sound of this, you could have the first known engine failure...for S2...or you could not.

You have the latest coils fitted at factory, the B's have not been known to fail..yet..

Are you using an 'abnormal' amount of engine oil?

 

Have you done a compression test?

The S2 has a different OMP system, right?
Is it also positive displacement like S1 or something else?
Just thinking outside the box here...
How does it react to higher viscosity oil??

 

Coolant is still the same level it's always been, I topped it off a few months ago, it's at the Full level though.

B2B is out, I'm passed 40k miles already. No real good dealerships nearby unfortunately, I might take 2 days off and take it to Pettit.

I had a compression test done like 2 months ago and it was in good condition, I still have the printout of the results somewhere if you want to know the #s.

Dealership swapped the plugs when they did the test, haven't checked what they are but I don't think they'd put bad plugs in.

Oil consumption has been about the same, 1-2 quarts every 1,000 miles depending on how much highway driving I do (I haven't done much lately so oil consumption has been fairly low). It currently has 5w30.

Once the engine warms up, it has no problem starting up.


Edit:
Engine scored a 7.8 on the test

 

Battery in good condition?

Did you ever clean the MAF Sensor BTW?...

 

Nvm
sounds like you're having trouble on your winter grade

Yeah, plugs and coils seem to be the universal fix for a rotary

 

I think I'm still running the original battery.. haven't thought to get it checked tbh.

I didn't clean the MAF, but ever since I checked the filter, pulled it out and stuff, it hasn't given me problems at stops, so dunno what that was about.

Winter hasn't really come around yet.. it's still over 85 degrees and humid as ***** sadly.

Would suck to have to buy a new set of plugs/coils bleh

I'll make an appointment with dealership for this week and see what they say.

 

If you have done over 40K Miles, I would definitely Clean the MAF with MAF Cleaner, they say it should be cleaned when Air Filter is renewed.

 

Crap! It was right at freezing this morning with a good breeze making feel much colder....

feeling a bit jealous...


Have you checked that the plugs are tight? I've seen a hard start caused by loose plugs.