richyvrlimited

iTrader: (1)

I have a very random misfire, it's pretty un-repeatable, it occurs 90% of the time during cruise, but can happen at any time.

see the attached pic from a datalog, (I can attach that if anyone wants it?)



you can see that the revs hold steady as does TPS and MAP, but where you can see the AFR fluctuate I have a miss fire, it's almost like the car doesn't fire on one cylinder. It's extremely annoying, especially now my daily commute now involves lots of steady state cruising :-(

I've got a set of Mazdaspeed Ignition leads and tried swopping them for another set with no joy (neither set are new however...) I've also tried new plugs, (NGK-R's and Iridiums) to no avail.

I'l literally at the end of my tether at the moment, long hours and a stressful drive does not make me enjoy my car!

Any and all advice is much appreciated!

ecugrad

Just an out of left field idea.

I had the DB25 housing screwed together, my IAT wire got chaffed and was grounding out on the housing. This caused a "stutter" that was completely random.

richyvrlimited

iTrader: (1)

that'd cause the MAT signal to look odd tho wouldn't it?

I'll check it out this weekend nonetheless!

Reverant

iTrader: (10)

Richy, please post the complete .xls and your .msq.

Jim

richyvrlimited

iTrader: (1)

Attached, thanks Jim,

I tried to use some of the PnP settings to see if it was setup related, that's why my VE and ignition tables don't match!

As an aside when I tried the PnP VE table it was Waaaaay to lean, it barely ran it was that far off - which I don't get at all as it should run right even tho I have much larger injectors, the Req_fuel setting should sort it out?

Reverant

iTrader: (10)

Right, which MSNSE version are you running and please tell me a location in seconds where it happens - exactly. Is 191.909s and 195.981s the deal?

Jim

richyvrlimited

iTrader: (1)

029q_hr iirc it's just been replaced with a new version on MSextra.com

and yup you've got the time bang on the money

Reverant

iTrader: (10)

I hate to break this to you but try 029t, the non-hr version. I always had hiccups and oddities here and there with the hr as well. If you still have the original injectors, you may want to swap them in for a test and drive along (no boosting obviously). Hope that helps,

Jim

magnamx-5

iTrader: (7)

hey check this out http://www.rivercityroad.com/garage/jumpingtach.html intermittent ground issue common on 1.8's wich causes misfires and eventual coil failure. It is a free and easy fix that might help.

richyvrlimited

iTrader: (1)

hrm, that's not good news :( I rely on the HR to keep a half decent idle with my rather large injectors :(

richyvrlimited

iTrader: (1)

oh oh ohhhhhh Now I have the jumpy tach sometimes and I'd heard it's sorted by improving the front engine earth. However i've never really been able to find it (not looked that hard mind....) I didn't realise that this was the front earth!

magnamx-5

iTrader: (7)

No sweat brah.