Rough Starts - Advice please
 

2004 MT 82K miles

Another stupid problem :wallbash:

My car has been having rough starts. It's somewhat intermittent, meaning sometimes itll spark right up; other times it will just keep cranking and finally just catch and the starter sounds like it's coughing....

There's no relevance to whether the car is warm or cold starts, it's a crap shoot either way.

I figured the same thing you're thinking at this point; replace plugs, coils, wires. Already did that, the new components have been on for roughly a week now...

The car runs like a bat out of hell when its going, only start up is rough.

I have a dashhawk, and it's saying the battery has proper volts both at idle and while running.

I have bigger fish to fry right now since I have a billion gremlins that are running around my car but this issue is annoying and embarressing as well.

Any ideas on what it could be or on further trouble-shooting towards this issue? I guess my next guess is the starter is on it's way out; before I go replacing more parts, is there anything else that could maybe help out during start up?

I've been doing a little research on grounding kits, would something like that maybe help a little?

What is the battery voltage while cranking?

I will get that information for you as soon as I get home. I never watched it while cranking :suspect:

While we are discussing it; also check the battery terminals as the negative side is notorious for fitting loosely.

Will do, I am leaving work as we speak and Ill be home in about an hour and some change (long commute). Ill hop in the 8 as soon as I get there and post the results..

Thanks again, hopefully we can nip this in the butt quick...

okay, its currently about 75 degrees ambiant out this way. Unfortunately, this start up was a 'good' one, so it wasnt duplicating the problem.... However, I did gather the numbers.

On accessory (Car not running) 11.75-11.85 Volts

While Starting - 9.0-10.0 Volts

At idle - 14.1-14.2 Volts

My bolt on the positive terminal has a crack in it I noticed. The bolt tightens down but only hand tight, I can unscrew it with my hand. Its stripped I guess... Not sure if that would be the culprit but its worth the couple bucks to get another bolt.

Are these numbers in line with where they should be?

9-10 volts means a weak battery and is llikely to be the culprit. Deal with the terminal connections, first, and see if that helps. Since you will have everything apart, clean all the terminal connections and reassemble it all, too.

Will do, Ill post updates as I proceed. Thanks again

Should be at about 12.5 with out the engine running and like charles said the 10 volts is weak, the 14 volts at idle is where it should be.

Yea, this battery isnt exactly new. And to be honest I do not take the best care of it. My car sits...... a lot. And I dont have the battery on a tender or anything, just sits in my gravel parking lot. The car didnt even get started for 9 months straight last year bc my trans was blown.


ssooooo, doesnt shock me this 3 year old battery is a little low on voltage, probably just going to buy a new one and skip the formalities of cleaning terminals, etc lmao.

Please continue to post your results. I'm having the same problem, although I consistently have that rough start you described. I haven't replaced coils, plugs, etc. like you have, but if the battery turns out to be your issue, I may start there.

Just fixed my rough start problem
 

A whole bunch of engine issues popped up over the past three months. I suspect it all started when a family member moving the car over one spot in the driveway in February - and then the dealership de-flooded the car with windshield wiper fluid.

First, I replaced the plugs and wires. This fixed the lack of power at the top end (above 4k rpm).

Then, I replaced the starter (get the new starter, not a remanufactured '04) it was hard to find. Make sure you buy a N3Z1-18-400 NOT the new N3H1-18-400R0A (it is a remanufactured unit and requires your core in exchange). It costs more, but the 3Z1 is a stronger motor. It starts right up, faster than ever.

Then, I got an optima red top, 35 class. This was probably unnecessary but I'm sick of wasting diagnosis time and have pretty cold winters.

Finally, I replaced all four coils. This fixed the lack of power at the low end (1-4k rpm). It also fixed the misfire that I was experiencing twice a week.

After inspecting all the old parts, I think that the coils and plugs were just worn out. They get 6x the use that 'normal' engines get. 3 fires per revolution (rotary) versus 1 fire every other revolution (4 cycle). That means that by 30k miles, they have as much use as a 'normal' car with 180k miles. Impressive. Also, the terminals on the starter were pretty corroded, which was probably why it was taking a really long time to crank and catch.

If I were to do it again, I'd replace the coils plugs and wires all at the same time. Make sure you watch the YouTube video to get the airbox out so that you have easier access to the coils and plugwires. http://www.youtube.com/watch?v=6I6_UnQELcw

Thanks for the advice, but Im a step ahead of you ;)

I know you replaced the coils, wires, plugs together - I listed all the info for anyone else who was reading. The part that is probably of interest to you is about the starter. I would guess that either you don't have the newer starter and the old one is wearing out, or the starter wire terminals are corroded and you're not sending enough juice to it.

Just wanted to post an update on my own struggles to fix a similar problem (hope you don't think I'm hijacking :o: )

My battery was only putting out about 440 CCA so I had it replaced with a Duralast Gold rated at 640 CCA. Unfortunately, I'm still having the exact same issue. It possible cranks a bit quicker, but still sounds like it's stuttering or skipping for a second or two immediately before turning over. Next things on my list are clean fuel injectors, replace coils, plugs, and maybe starter. The plugs are fairly new so probably coils will be first to go.

That's exactly what mine sounded like. My battery was rated at 640cca and tested at 545cca. The Optima I bought is rated somewhere up around 8-900cca and made little to no difference. Then I put in the new starter (which had non-corroded terminals), and it started right up. There was still a mis-fire every once in a while but that was because two of the coils were bad (they still worked, but not reliably). I called the guys at finish line performance / rosenthal mazda and they found me a N3Z1-18-400 the one that is listed on their site is a remanufactured '04 style starter (smaller motor). If it's easy to get the car up off the ground, I'd get under there and take the terminals off, clean them with a wire brush and scotchbrite pad, put some dielectric grease on them, and put it back together. If that doesn't work, then it sounds like you're in for a new starter and then maybe coils and plugs.

I had the starter replaced with the 'newer' one when they had that tsb. It was a long time ago around the time when I first bought my car (2006 ish 20-30K miles-ish).

Mine doesnt crank slow like most other rx8s Ive hear, mine cranks fast then itll feels like its trying to catch, skip a crank, then finally catch a little.

Best way to describe the starts is it sounds like its coughing.

I havent really looked into this since my last post, havent really had the time. My RX8 has sat for over 2 weeks now without me touching it lol. Damn work schedule....

Something kind of worked: I tried leaving the key in the "on" position for about 10 seconds to build up fuel pressure (read of this idea somewhere else) and it seemed to start up better. Still cranked for a few seconds but didn't 'cough' anymore. I may try a fuel injector cleaner in a few days. Maybe if I can get more fuel in there on start, it'll turn over quicker. Experts?

Of course, something else had to go wrong...now my tire pressure light is on. Ugh

yea I do that regardless. Its been bad since my car sat for 9 months straight last year without moving. IDK, like I said I have more issues that are of more urgency anyways, but this car is literally for entertainment purposes only so Ill just add that to my RX8 bucket list to tackle over the winter.

if anyone is curious, here's the current list:

ABS/Trac control lights on (Mazurfer has already given me DIY's for that)
Rear Wheel Bearing Replacement
Trans Output Shaft Seal Leak
Rear brakes (Sitting in my apartment, for a while now lol)
Coolant Flush

You shouldve seen the list at the beginning of last summer, it was (literally) 4 times the size, my cars made a lot of progress. So Im just ironing out the final kinks of 5 years and 83K miles and its back to modding.

Ah, alright. Well it'll become part of my normal routine now. Still has trouble starting when the engine is warm, but it stutters much less when cold now. Gonna try to clean the fuel injectors, then it's on to coils and starter. My plugs only have about 8k miles on them so they should be good.

Not sure what the deal was with my tire pressure light. It's off now...

Good luck with your list :)

Thanks, only problem is whenever I get that list down to 1 or 2 items, something else gets added lmao.

hence the 'neverending project' under my Name :rofl: