Little background.. In 2004 I didn't really know much about Miatas, shortly after a friend bought his 1994 his crankshaft had a failure. We think NOW that the bolt wasn't replaced after timing belt service was performed on the car before he purchased it. We opted to replace the oil pump while we had it apart, new crankshaft (well, new used) and new bearings. That was around 120,000 miles.


Fast forward to now, hes got about 207,000 miles of HEAVY abuse on the car, and about 30,000 of those have been with 8psi from an M45. (Think 7000rpm clutch dumps, about 2 a day.) So if we're on the highway and you downshift into fourth and stand on the throttle, the engine will get to about 5600rpm when the Oil pressure gauge will start to drop, then FLUTTER!! At the same time this is happening, it almost sounds like detonation coming from the engine... Might also add since this started, engine compression has dropped a little bit on cylinder number two.

For some reason my leakdown tester works on 5 different engines, just not his. We try and do leakdown on his car and all four cylinders read 0 leakage, which I know for a farking fact is a lie... You can hear it leaking out of the intake, exhaust, and valve cover..

Compression numbers are:

1: 120psi
2: 110psi
3: 118psi
4: 115psi

Is that floppy piece of **** Advance auto () oil pump about to explode? If the engine blows up we really don't care, I'm just curious if anyone else has seen this happen?

 

Apparently, the stock oil pressure gauge works pretty well as a detonation sensor. The fluttering happens when there is detonation.

As far as indicators of oil pump failure, mine just flat out failed with very little warning. I got intermittent shuddering from the engine for about 10 miles, then the engine just froze.

 

Stock OP gauges fluttering = DETONATION. Your friend is just killing his engine. The oil pump has nothing to do with it, he's just bending the motor over day after day after day.

 

so almost 80k miles of rapage...and 30k miles of boost on a rather stock motor that gets beat to ****...she is prolly just dying...

 

Sometimes my gauge will flutter at idle w/ no accessories on. Can detonation happen at idle?

 

No. Detonation only happens under high load.

 

all of my guages flutter all the time, but then again, i do have MMR motor mounts

 

Its a 1994 so the gauge isn't just an idiot needle, it actually moves with pressure.. Still the same deal?

 

Yes those are the only ones that work to sense Det.

 

Quick, now everyone start selling your 'real' oil pressure gauges to Honda owners at "detonation gauges" lol

 

M45, need you say more?! Detonation. The come hand in hand. A good advertising campaign for the M45 would have been, "Come and knock on my door."

 

Ok, thats just gross. Lets keep it clean and respectable.

 

Other M45 advertising campaign slogan ideas for the M45:

"It's a hard knock life"

"Moma said knock you out"

"Knock on wood"

"Knock three times!"

 

Knock, knock.

Who's there?

Tom, with a nice box full of detonation for you!

 

So if your motor went bad because of detonation, then would it be right to say you car got knockedup?

 

 

Given the mileage the rings were probably starting to go. Increased oil consumption (due to age) will increase pre-ignition and start causing knock. Once the knock goes untreated you will start cracking ring lands and ******* the motor up at a significantly increased rate. I suggest looking for a new short block.

 

You guys rock!!

 

Yep. Something having to do with the knock noise interfering with the oil pressure sensor, so you get a very distinct wiggle back and forth. I've seen it ONCE before, and I immediately got the laptop out, datalogged, replicated it, and pulled a degree of timing out in that cell. No more wiggly after that.

 

I didn't know / think the oil pressure gauge had anything to do with detonation, and thats funny as hell. Guess I should have ignored the gauge and listened to my ears. Guess I was in denial that the motor would actually detonate that much when its 10 degrees outside..

New motor is in my garage. To be honest, I'm REALLY surprised that it hasn't blown up yet.. You know, P-P-P-P-POWERCARD!!!! and all.. along with that piece of **** jackson racing ignition retard.