My MR2 is sick Oppo

"Nauraushaun" (nauraushaun12)
06/05/2016 at 20:08 • Filed to: HELP

Could the infinite wisdom of Oppo help me with some diagnosis?

The symptoms:

First and foremost, a metallic rattle that happens in time with the revs. Happens in all gears including neutral, but only at ~20% throttle and only when the engine is thoroughly warm and more or less only between 2500-3000 RPM. We have attempted to find something obvious to no avail, and have adjusted the valve clearances with no change to the behaviour. It happens when trying to maintain the same speed - accelerating a bit lighter or harder usually stops it.

Hesitation at specific RPM. Around 2000 RPM during acceleration it tends to stutter once or twice before continuing on just fine.

Hesitation at high RPM. As it gets above 4000 RPM it starts to seem to really choke. It’s never had the puff of my old 300ZX at high RPM, I chalk that up to less cylinders/displacement. But recently it seems to suffer more than normal, even to become peaky. Acceleration will come and go rather than linearly increasing throughout the rev-range.

Considerations...

When I first noticed the rattle I checked the oil and it was very low. The oil pressure light wasn’t on (perhaps it’s broken). Whether this is related or not is anyone’s guess.

Problem 3 could be partially in my head. Maybe the rattle is making me see other issues that don’t exist. I’ve had the car about 9 months and take it to higher RPM relatively frequently, I’m pretty sure it feels off.

The sporadic nature of each symptom is probably the hardest part. Every time I think of a potential cause I have to ask but why does it only happen at certain RPM/temperature/throttle position?

I took it to a mechanic and he said the valve clearances need adjustment (which I’ve since done). But he also said the head had to be removed and machined, which means the engine has to come out, so he may as well do the timing belt, and quoted me literally billions of dollars. I haven’t done these bits and I’m not sure why he thought I should.

DISCUSSION (25)

HammerheadFistpunch > Nauraushaun
06/05/2016 at 20:16

sounds bottom endy to me, but it could be something as simple as a loose/cracked heat shield or exhaust bracket.

My citroen won't start > Nauraushaun
06/05/2016 at 20:19

Your engine is bored, you need slides

Kinja'd!!!

daender > Nauraushaun
06/05/2016 at 20:28

Yeah, try tightening the exhaust shield first.

Chan - Mid-engine with cabin fever > Nauraushaun
06/05/2016 at 20:41

For the sporadic metallic rattle, I vote exhaust or gearbox, in that order.

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > Nauraushaun
06/05/2016 at 20:43

Does it do it with the clutch in and out? I had a similar noise with a vibration once in a Camaro and it was a broken clutch disc. So it did it with the clutch engaged but not disengaged.

Nauraushaun > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms
06/05/2016 at 21:47

I think so. It does it both in and out of gear...but maybe I’ve only tested it in neutral and not actually with the clutch in. I’ll check that, that would be an enormous clue

It certainly does it with the clutch out.

Nauraushaun > Chan - Mid-engine with cabin fever
06/05/2016 at 21:48

Could it be gearbox if it happens both in and out of gear?

Would an exhaust rattle be likely to only happen in such specific situations?

Nauraushaun > daender
06/05/2016 at 21:48

It sounds more like it’s the engine itself. We tried poking around the exhaust shield and it seems pretty well fixed. But that’s only looking from the top...

I’ll keep it in mind

Nauraushaun > My citroen won't start
06/05/2016 at 21:49

My engine gets plenty of slides, don’t worry. I bent a rim on a curb the other day. It’s my secret shame, I’m still trying to come to terms with my stupidity.

Nauraushaun > HammerheadFistpunch
06/05/2016 at 21:50

I sure hope so! Maybe I can get it on my friend’s hoist and investigate that area.

I have taken it to a mechanic. He quoted me an astronomical amount, but I assume he’s done a decent check of these things and ruled it out.

But assumptions are the devil’s playground :(

LOREM IPSUM > Nauraushaun
06/05/2016 at 22:15

Find an indy who knows those cars inside and out and put it in their hands.

This thing obd2? The rattling could be bad cats. If they’re breaking up inside the element can shift and block exhaust flow causing rattling and hesitation and misfiring under wot. Jack her up and bang on the cats with a rubber mallet. If they rattly they may be bad.

Or...rattling could be the throwout bearing, and hesitation could be intake or vacuum leaks. Smoke test to check for leaks. Drop tranny to check t.o.b.

4kc > Nauraushaun
06/05/2016 at 22:30

yes

MR2_FTW - Group J's resident Stig > Nauraushaun
06/05/2016 at 22:57

Is it a 3S-GTE or a 5S-FE?

Nauraushaun > MR2_FTW - Group J's resident Stig
06/05/2016 at 23:20

It’s a 3S-GE

Nauraushaun > LOREM IPSUM
06/05/2016 at 23:20

I did and he asked for $2500 lol. And I’m not sure he was right.

It doesn’t sound like an exhaust thing. My 300ZX had a rattly cat for years, it was just very different.

Bearing is possible. Leaks is too. I’ll check for those.

petebmwm > Nauraushaun
06/05/2016 at 23:34

The sporasic stumble could be injectors, i had this in my e30 m3, always at the same rpm and fine after

Nauraushaun > petebmwm
06/06/2016 at 00:05

That’s interesting. I’ll have a look at them. Did you replace them? Clean them?

E92M3 > HammerheadFistpunch
06/06/2016 at 00:05

That’s what I was going to say. If it only happens at a certain RPM, and/or is sporadic, then it’s most likely something on the outside of the engine. If it was rod bearings, or something in the valvetrain it would change with the RPM, and be consistent. My bet is something exhaust/cat related, rattling from vibration.

petebmwm > Nauraushaun
06/06/2016 at 07:49

Replaced the bad one snd it was good

MR2_FTW - Group J's resident Stig > Nauraushaun
06/06/2016 at 09:30

Neat. I wish we had that engine option over here. The 5S has nice low down torque but doesn’t much care for high RPM shenanigans.

Niko's Work Account > Nauraushaun
06/06/2016 at 10:08

It’s AIDS :\

Chan - Mid-engine with cabin fever > Nauraushaun
06/06/2016 at 13:06

Possibly, because the gearbox has shafts and bearings that spin with the flywheel in Neutral.

Exhaust rattles are known to be very particular about RPM and engine load, so I wouldn’t be surprised. It would help to be able to hear the rattle while standing outside the car.

Nauraushaun > Chan - Mid-engine with cabin fever
06/06/2016 at 21:46

I see, makes sense. From outside the car it doesn’t sound exhausty, but I could be wrong.

Nauraushaun > Niko's Work Account
06/06/2016 at 21:47

Oh no :(

Nauraushaun > MR2_FTW - Group J's resident Stig
06/06/2016 at 21:48

Coming from my old Z the 3S doesn’t feel especially strong at high revs. But it does a fine enough job.

When it’s not fucked like mine is lol