Does anybody do this? Im hoping it will smooth out my rough idle, only idles rough when engine is warm. Runs like a dream when its cold. Its a 2004 manual rx8 with 43k on it. I don't suspect plugs and coils because it only idles rough when warm. Was wondering if anyone puts 2 cycle engine oil in their gas tank? Or will that just screw everything up completely

 

Gab,

Many of us premix. Read the thread i have posted below. It should help answer any questions that you have about it.
https://www.rx8club.com/series-i-tec...-thread-99636/

As for the rough idle, when was the last time you had coils, plugs and wires changed? Have you had a compression test done lately?

It's also a possibility that the issue could be engine mounts or an entire host of other issue's...
https://www.rx8club.com/series-i-tro...h-idle-236385/
https://www.rx8club.com/series-ii-te...h-idle-238040/
https://www.rx8club.com/nw-rx-8-foru...roblem-232500/
https://www.rx8club.com/series-i-tro...h-idle-247180/

Hope that helps.


Travis

 

It wouldnt be engine mounts because its only when the engine is warm. It is an abnormal sputter/ rough idle. Kinda like a misfire. Interior dome lights slightly dim when the engine is warm and idling and when it "coughs". As for the link to the other thread, there's so many mixed opinions its hard to find a definite answer. I just bought the car two weeks ago so idk then coils and plugs were changed but I suspect some sort or fuel to air ratio being off or unburned oil in the engine. But you guys would know more than me

 

How long does it take to start? Cold and Hot just wondering

 

Put 6 oz into a tank - see what happens

If you can get a compression test

Try to get your vacuum at idle

Check for vacuum leaks

 

^^+1, vacuum leaks cause bad idle. When i had a rough idle ONLY when the car was warm also, rpm would jump a bit at a stoplight, i did indeed have a vacuum leak at the time, but i took it in for a compression test, and engine failed horribly.

 

Cold it takes like 1.5 sec
warm it takes like 1.6 sec.

 

Ill try to see if I can find any vacuum leaks after work. What do you mean try to get your vacuum at idle? also if I add 2 stroke oil to the gas will I have to play with The mop at all or what? You guys are a big help, thanks guys

 

Im also not exactly sure where to look for vacuum leaks ill try looking for another thread explaining what lines to check

 

Did it fail because of the leak or because of an apex seal or something like that?

 

gabe, you need to read through this thread: https://www.rx8club.com/new-member-f...t-here-202454/

Not only does it have a section on Premix (2-stroke oil in gas tank), it has information about Methods of Engine Failure, How to Address Engine Failure Methods, why you need a Compression Test, and what the Compression Test Means


A vacuum leak can be confirmed through either OBD2 data (like with a bluetooth OBD2 adapter paired to your smartphone), or by visually checking all of the main possible vacuum leak points. If the data shows a leak and a visual check can't find it, you can take the car to a shop that can smoke test the intake system, which basically means you will see smoke coming from the location of the leak.

Don't just jump to conclusions though, educate yourself about the possibilities and work your way through testing and solutions till you find it.

 

Vacuum leak did not make it fail, it was just low compression in general. RIWWP just posted a great post for you. And smoke test are very helpful, probably cost 60-80$ at a shop to smoke test for you. If you want to do a quick check yourself, buy carb cleaner, let your car idle, and start spraying all the lines/connecting points, if ur car idles differently you most likely have a leak at that point.

 

I used soapy water in a spray bottle to find vacuum leaks but didnt find anything. I just noticed some sort of clicking noise behind the alternator. not sure what its coming from but it seems to come and go

 

You don't even know that you have a vacuum leak yet, so if you don't see something obvious, trying to look more is mostly a waste of time. Get an OBD2 data source and see what your MAF g/s and fuel trims are at hot idle. That will tell you if you have a vacuum leak or not.

 

Update: so I replaced the coils, plugs, and wires today. It was a pain in the *** haha, but the coils had the white arc marks on the bottom of them (as shown in picture) I ordered the coils from front to back (if your facing the car, the first coil is 1 and last is 4) the plugs in front of the coils and the plugs that went to that coil. The first two coils had the white marks also but they werent as bad and I rubbed them off. (Coil 4 was worse than 3 and 3 was worse than 2 and two was worse than 1)

So the big question, did it fix my idle problem? The answer is yes. It definitely cleared the inconsistent "coughs" from the engine. Also the odd clicking appeared to go away (only checked it real quick cause it was really dark by the time I was done) so the car still seems a hair shakey (barely noticeable but consistently shakey) its probably a normal shake. (When I say barely shakey I compare it to a Cadillac where you wouldnt even be able to tell the car was on) you probably cant tell the car is on unless youre trying to feel it which might be what im doing on accident. I guess I cant add pictures sorry. If there is a way to add pictures please let me know. Thanks guys

 

White marks...





...don't mean anything.

You clearly had ignition problems, but the white marks show up on good coils, and may not show up on bad coils.

 

Oh I watched a YouTube video and the guy said that it meant the coil was arcing and was bad. I posted pictures on a photobucket account. Here's the address:

http://s1378.photobucket.com/user/Gabe_Slezak/library/Mobile%20Uploads?sort=3&src=pb&page=1

 

Did the coils/plugs make this quicker? Id say once it gets to the 2 second range to start worrying, cus my starts were at about 1.8-2.1 seconds. I mean as long as you have no other problems that is.

 

Yeah, "white marks = arcing" or "white marks = bad" is a common myth and misperception. It's why Mazda had to release the above publication to specifically tell dealer techs to stop diagnosing coils based on the marking.

 

New plugs, coils, and wires do not seem to have affected the start times at all

 

That makes sense. But isnt arcing bad?

 

Okay well glad you fixed your idle and everything! Just watch those start times. Mine was in that range of 1.8ish.. With ONLY rough idle when hot was my only bad symtpoms, and it not only failed compression, it BOMBED it with mid 5's and low 6's on all faces.

 

It's only bad if it can be a source of ignition to some kind of fuel. Unless you're leaking fuel at the engine it's fine and doesn't harm anything.

The reason people think it's bad is because arcing into electronics is generally a bad thing, as it can harm the components. When sparks are arcing out of high voltage electronics directly to ground nothing happens. Ignition coils are designed in a way that allows them to arc to the nearest ground as a type of current regulator by releasing excess charge ahead(?) of the release mechanism.

All coils will do it to some degree, but the white spots come from a combination of random variances in charge voltage (effecting arc voltage), and random variances in epoxy quality (effecting spot size/whiteness).

 

The little shake / vibration may be due to engine mounts going bad, or dirty MAF.
Try Cleaning the MAF, Clean the Intake box, and accordion tubes as well even if they are not the culprit they will help stabilize your idle and help car breath better :-)

If the problem still persists then have your motor mounts inspected, another way to tell is your gear gear shifter will shake, tilt the sunroof and it will vibrate..

 

This could be a grounding problem as well.