[Miata] '02 Miata Bucking Without CEL - Big Mystery!

[Ron Zander]

Sounds like the heat is the key component. It also sounds electrical.  
Dropping a cylinder wont make the car 'buck' as you say, it would run  
rougher but at 3-4k still be fairly smooth. The bucking sounds more  
violent, as if you are loosing all cylinders. This means either you  
loose fuel or ignition. I think it's likely more electrical in nature.  
The idea of real-time logging like Larry suggested is a great way to t- 
shoot it. I'd look into that. I could really be anything from coils to  
the ecu at this point, you've got to get more information about it  
when it's occurring.

On May 27, 2008, at 5:23 AM, Bryan Wyatt wrote:

> Each time, it was 70-85deg F and humid but not raining.  Strangely  
> enough, it's been raining like crazy up here and the car's been just  
> fine.  Each time it's acted up, the weather's been generally "good"  
> if not cloudy.
>
>
> -Bryan
>
> --- On Tue, 5/27/08, Larry Alster <Larry at Miata.net> wrote:
>
> From: Larry Alster <Larry at Miata.net>
> Subject: RE: [Miata] '02 Miata Bucking Without CEL - Big Mystery!
> To: bryanewyatt at yahoo.com, "'Miata Mailing List'" <miata at realbig.com>
> Date: Tuesday, May 27, 2008, 8:01 AM
>
> Bryan
>
> What was the weather like??  Was it raining or had it been raining  
> before this happened??  I used to have an issue with my Toyota in  
> the 70’s where whenever it was wet or humid I lost cylinders and it  
> didn’t want to restart.  The problem ended up being that the factory  
> clear coating on the cam cover had failed and I was getting an arc  
> over from the wires to the cam cover whenever it was humid.   
> Painting the cam cover with engine paint solved the problem.
>
>
>
> Larry
>
> White Knight      1991 Crystal White   #99 CSP
> Silver Bullet        1992 Silverstone     #17 SM2  FM I+ Turbo
> Honey B             1992 Sunburst Yellow #99 SM2L  JR Supercharger
> Whooosh           2004 Titanium Mazdaspeed MX-5
>
> LowCountry Miata  http://www.lowcountrymiataclub.net
> Masters Miata
> RAGS 074
>
> From: miata-bounces at realbig.com [mailto:miata-bounces at realbig.com]  
> On Behalf Of Bryan Wyatt
> Sent: Tuesday, May 27, 2008 7:44 AM
> To: Miata Mailing List
> Subject: Re: [Miata] '02 Miata Bucking Without CEL - Big Mystery!
>
> I've been thinking of changing the wires to Magnacores anyway, so  
> this might be an excuse.  They seem to cost almost twice as much as  
> the old reliable NGK Blues, though.  Everyone I've talked to says  
> they're worth it, but I'm a little skeptical.
>
>
> As hot as my car seems to be (seriously, I don't remember Junior  
> getting this hot), the exposed wires near the harness points just  
> seems like an all too likely candidate for shorting out at high temps.
>
>
> You had an experience like this one, Mark?  Was there anything  
> different about it?
>
>
> -Bryan
>
> --- On Tue, 5/27/08, mark moore <miata at bwr.eastlink.ca> wrote:
>
> From: mark moore <miata at bwr.eastlink.ca>
> Subject: Re: [Miata] '02 Miata Bucking Without CEL - Big Mystery!
> To: "Bryan Wyatt" <bryanewyatt at yahoo.com>
> Date: Tuesday, May 27, 2008, 5:33 AM
> Bryan for what it's worth the wires can fail. I have had to replace  
> the OEM set and a set of the RB Ultras. We have a lot more miles on  
> our car though. We had an issue somewhat like yours when we were a  
> long way from home (southern US) and it scared the wits out of me as  
> it happened on the highway in traffic. We made it back home to  
> Canada with the issue reoccurring only once I believe. In our case  
> it was the wires and a very occasional thing.
>
> I don't recall the exact circumstances at the time but don't rule  
> them out as a potential cause. Maybe consider all the other advice  
> first and get new ones if you have to. NGK make them now and the  
> price is reasonable. I haven't heard of coils on an 01+ being a  
> problem.
>
> One other odd thing we had happen to a club member was the  
> immobilizer in the key causing the car to shut down but then it  
> could be restarted. Again an erratic thing. That one took the owner  
> about six months to track down and correct!
>
> Mark
>
>
> My car is an '02, which means that I don't have coil packs--just the  
> coils on plugs 2 and 4.  I checked the wires and ensured that they  
> locked in place both at the coils and on top of the plugs.
>
> As for wires, I was under the impression that 01+ wires seldom need  
> replacing.  How about the coils?  That's $235 or so to replace 4  
> parts!
>
> -Bryan
>
> --- On Mon, 5/26/08, Hank <Subhunter at verizon.net> wrote:
>
> Don't know about your year car but plug wires going bad at around 20  
> - 25Kmiles regardless of appearance is a very common problem common  
> to Miatas and when they go bad you get some strange indications.   
> Those that you mention aren't out of the ball park.  Also possible  
> that you've cracked the insulator on a plug or that for some other  
> reason one of them's shorting out under heat.  Other then that  
> there's always a possibility of an electrical short under the hood  
> due to heat and vibration, give all the plugs and wiring under the  
> bonnet a good physical check for security seems in order.
>
>
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