[MSCW List] No power under 4000 RPM - New Engine - No Miss

zbrowns zbrowns
Sun Nov 5 15:55:28 CET 2006

The 1990 Miata is running like a champ again!  

My biggest lessons learned over the past 5 months - Trust the advice from
club members - Howard Wetzel kept telling me - The problem sounds like a
classic broken crankshaft problem.

Much thanks to all the MSCW members that responded to my e-mails!
- Howard Wetzel for coming out to the house to lend a hand.  
- Bob Circle for the used engine at a great price (US Navy trained too).
- Phil & the mechanics @ Gaithersburg Mazda for their advice at Tech Night
- Jane Clarke for the info on the Tech Session.
- Pete & Joey @ PBC for talking me through all the oil seal replacement, and
the parts.
- Bret de Pedro @ RP Performance for the advice.
- Jim Thill for the engine removal tips.
- Larry Jackson for the Airflow Meter.
...and all the advice from the MSCW members at last Wednesday's meeting that
convinced me the "new" sparkplugs could still be the cause of my mysterious
miss in the engine.  

So after, a replacement engine, all new lip seals, new clutch assembly,
timing belt, tensioners, water pump, oxygen sensor, coolant sensor, plug
wires, two sets of sparkplugs, and talking with some of the best Miata
enthusiast around - my 1990 Mariner Blue is running like new again.

This form is great!

Greg Brown
1990 Mariner Blue
Cell 703-209-1220
zbrowns at verizon.net
gregory.m.brown at navy.mil
Date: Fri, 15 Sep 2006 
Subject: [MSCW List] No power under 4000 RPM - Broken Crankshaft Nose

Thanks to Phil at the MSCW fall tech session at Gaithersburg Mazda, and MSCW
member Howard Wetzel for all his advice over the past several weeks, I
followed their disassembly advice and discovered that my lack of power was
because the crankshaft nose was broken off.  No chance of a weld repair or
Loctite 660 repair now.  Other than the crankshaft, the car is in pristine
condition, so I intend to replace the engine.

Anyone have a lead on a used 1.6L or 1.8L engine?  

I appreciate everyone's helpful advice, and my wife and I enjoyed ourselves
at last nights tech session.

Greg Brown
1990 Mariner Blue
Cell 703-209-1220
zbrowns at verizon.net
gregory.m.brown at navy.mil

Date: Sat, 29 Jul 2006 14:44:58 -0400
From: "Greg & Idi Brown" <zbrowns at verizon.net>
Subject: [MSCW List] No power under 4000 RPM - Problem Continues
No power under 4000 RPM - Problem Continues.

Well, I replaced the leaking cylinder head cover gasket, sparkplugs, plug
wires, air cleaner, and fuel filter, without any positive results.  The
problem is intermittent (about 50% of the time), but sometimes reveals
itself when I turn the a/c on.  I was doing 75 mph, turned the a/c on and
the car quickly slowed to 50 mph and more gas does not help. Turned the a/c
off and the power came back slowly, then was fine.  While standing still
holding the idle at 3000 rpm, as soon as the a/c is turned on the rpm drops
to 2000 rpm.  Sometimes it acts-up while the a/c is off too.  I thought it
may be linked to the crankshaft defect (the engaged a/c compressor loading
the crankshaft pulley), but everything appears to be in place. Compression
on all cylinders is around 175 psi.  I did notice while doing the
compression check, turning the engine over with the plug wires off the coils
arcing from one port to the other, and toward the cylinder head cover.  Not
sure if that's normal.  The onboard diagnostic is still showing clear.  I've
rechecked vacuum lines and do not notice anything loose.

Any other ideas/advice would be appreciated.

Greg Brown
1990 Mariner Blue
Cell 703-209-1220
zbrowns at verizon.net
General Problem May Be Solved -
I replaced the airflow meter with a used unit without success.   
After reading dozens of miatanet comments pointing to the plug wires, I
pulled all the plugs and found the #4 plug was soaked with oil leaking from
the cylinder head cover gasket.  It appears that it was shorting out the
recently replaced wires.  The sparkplug itself was oil fouled.  I cleaned
everything off with brake clean, and it seams to run better.  The on-board
diagnostics is clear of failure signals, but it is still running a bit
rough.  This may be from the #4 plug becoming fouled from the short.

Thanks to members Larry Jackson, David Lane and the guys at Performance
Buyer Club for proving advice.

Greg Brown
1990 Mariner Blue
zbrowns at verizon.net

Subject: [MSCW List] OBD - Airflow meter / Ignition pulse - No power
under 4000RPM until engine warm (ten minutes).

1990 Miata, with 118k miles, has run flawlessly until left out in rain for
several days.  New ignition wires this year. The engine always has had a
boost of power at the 4000 rpm point.  Using On-board diagnostics to observe
the "CHECK ENGINE" light on instrument panel, it indicated 8 blinks -
Airflow meter, then 1 blink - Ignition pulse.  Following the factory service
manual, the airflow meter indicated Replace.  While no obvious loose wires,
I haven't tested the ignition coil and igniter yet.  I'll make one change at
a time.

Anyone had a similar experience?

Anyone have a used Airflow meter they are parting out?

Greg Brown
90 Mariner Blue
zbrowns at verizon.net

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