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Lee_The_CI
09-26-2008, 12:11 PM
Just wondered if anyone else had a small misfire at 3800-4000rpm?
The car is a 2000 with the coldside setup + 115mm pulley + timing card.
It has new plugs and new wires, and a used low milage set of coils.
It only happens when the car is warmed up and only in the higher gears under WOT.
Any input would be appriciated.
Thanks
Lee
Tom @ Fast Forward
09-26-2008, 05:56 PM
Lee,

Curious what the A/F does when it happens.

Does it happen at WOT or only when easy accelerating?

Any idea what boost it is at and, is the boost consistent, when it happens? (Always 4 PSI, for example?)
Lee_The_CI
09-26-2008, 06:10 PM
Tom,
A/F is steady at about 11.7
Seems to only happen at WOT in the higher gears, 3rd and up.
I will run some more tests this weekend.
Thanks
Lee
Tom @ Fast Forward
09-26-2008, 06:13 PM
Pop the belt off and see if it happens with no boost.
maggie
09-27-2008, 05:22 PM
My car had a miss at 4050 rpm that I always wondered about. Usually while accelerating. Mysteriously it went away after my install. I am now having a problem making power over 5000 rpm. I wouldn't have suspected the coils because the car only had 4k miles when I bought it and now has 16k but it looks like that coils might be the culprit (thanks for the phnoe support the other day Tom.) I'll be researching COP,s or factory replacements (expensive :mad:) next week.
Tom @ Fast Forward
09-27-2008, 05:33 PM
Try a set of BKR7E gapped at 0.025" and see if that helps. If so, it confirms weak coils.
Lee_The_CI
10-08-2008, 09:10 PM
Well I found my misfire. There was a frayed wire that was part of the crank sensor. The wires run from down near the crank pully up to the front of the engine right past the power steering belt, not a great routing Mazda!
Just one more thing for everybody to look at if they are chasing a mysterious missfire.
Lee
Tom @ Fast Forward
10-09-2008, 09:31 AM
:party:

Intermitents are hard to find. Glad you found it. Mine irritated me for a long time and I only found it after it was no longer intermitent.
MX-Drew
10-10-2008, 03:35 AM
Another good one to check it a broken wire to one of the injectors.

Just another one for the list of things to look for :taz: