The intake manifold brace was removed when the FM turbo kit was installed due
to the inclusion of the PWR Twincooler radiator/oilcooler. The oil hose
routing necessitates the removal of the intake manifold brace. The starter
bracket is secure. I haven't checked all of the lower intake manifold nuts,
but the ones I could readily reach were secure. I don't have any vacuum leaks
so this is a little less likely, but I will check tomorrow. Also I have stage
8 fasteners of the turbo, DP and exhaust manifold. These are secure as well.
I just ordered a new sensor (they are Bosch units from a 91 Porsche 944 w/ the
3.0 liter motor, bosch part # 0-261-231-006) locally and will go pic it up
tomorrow afternoon. Hopefully that's it.
Myron
----- Original Message -----
From: Ray Ayala
To: M. Ybarra ; Miata Power List
Sent: Friday, November 07, 2008 4:36 PM
Subject: Re: Obiwan Knock sensor acting up, any ideas?
The noise source may very well be on the other side of the motor. Peaking in
a fairly narrow rpm range certainly does suggest something resonating. I've
seen four such things over the years ... the intake manifold brace (loose bolt
at the top end), the intake manifold itself (brace missing and one loose
manifold bolt), the starter (front brace missing so the entire started acted
like a tuning fork), and a loose downpipe flange bolt.
----- Original Message -----
From: M. Ybarra
To: Miata Power List
Sent: Friday, November 07, 2008 11:45 AM
Subject: Obiwan Knock sensor acting up, any ideas?
Early this week, I was accelerating in 2nd gear on an on ramp getting onto
the freeway when right around 5000 rpm and I got a knock event, just 1. I went
to 3rd to about the same rpm and got another. The Link pulled a substantial
amount of timing as a result. I assumed I got a bad batch of gas, so I kept
out of boost and when I got home I put in some of my race fuel (about 2
gallons) and left the existing map alone as I have been running this ecu street
setting for about 3 years. Ran the car again and the same thing happened. I
got the car home again and went to the knock screen on the Link pad and rev'ed
the engine to about 5000 in blips. Since there is no load on the engine I
figured that it's shouldn't register anything. Unfortunately the knock #'s
rose to 40 really quickly then back down to 1.
Well, I figured that I have something loose near the sensor (which is what
Keith @ FM suggested as well) so I put the car up on my lift this morning and
checked every bolt or nut I could get my hands on; bell housing, motor mounts,
starter bracket, oil pan, ancillary brackets all the way up to the valve cover
bolts. Nothing is loose. So I figured that maybe the Quaife with all of it's
racket could be causing it, so I pushed in the clutch to quiet the gear set and
rev'ed the motor to 4500 rpm, the numbers shot up to 38 really quick then came
back down to 1 when I released the throttle just like the first time. So, I'm
at a loss. Could the sensor be going out or am I missing something else?
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