I've been puzzled by my most recent car issue and have not been able to find a similar problem on the boards. Here are the cars specs:

03 Miata VVT (disabled by MS3)
FM2 Turbo
Megasquirt 3
FM Clutch

I installed my turbo kit around 5-7000km ago, had it tuned conservatively (I spent a lot of time figuring out conservative timing numbers) and have not needed to touch the car since (more or less).

My problems started Monday while driving on the highway. I was in 6th gear driving at around 120KM/H (70MPH) when I had complete loss of power. My foot position had not changed but my revs were dropping. So I downshifted into 5th and tried to add gas to pick me up. My revs continued to drop but I could hear the engine working. I downshifted to 4th and all of a sudden, everything came back. The revs came up, and the car began to drive "like normal". I finished my 3 hour drive that day without a problem-- however I did feel a slight loss of power.

The next day I went to start my car and noticed a few things. The car has lost its "throatiness" or deep tone when it starts. It also doesn't hit boost as quickly as it did. Also, I don't feel like the boost levels transfer to the same power output as it did before. For example, when I hit 4PSI, I don't feel the same acceleration as I did before- It's a lot weaker.

I originally thought this was a clutch issue but after talking to a few people, the symptoms don't match. I also had my clutch replaced with an FM when I installed the turbo.

I don't think this is a turbo hardware/ MS3 issue as I had put a lot of time figuring things out/ did not take the cheap route.

I have yet to conduct a compression check and think thats the first place I should start.

Either way, if anybody has run into a similar problem let me know!

P.S. I do not drive the car hard- it's my DD. I rarely get to do spirited driving, but I was doing it all weekend-- so this might be a contributing factor. However, I'm confident the tuning was done properly, so the car should have no problem with being pushed.

 

I do. Sounds like a sensor, a wire, or a ground

 

Clogged Cat?

 

Any idea where to start on this one? Sensor/wire/ground from MS3 or engine--> chasis? I do know that I've had a ground issue with my passenger headlight (it's really dim). I've been trying to hunt that down and maybe this could be a good place to start.

As for the cat being clogged-- I had the whole exhaust replaced with FM parts, so they are practically brand new. How do I check if the cat is clogged?

 

Post a video of how it sounds. I would guess running on 3 cylinders? That would explain all fo the symptoms.

 

Update:

Compression test came out a bit low: 145-140-145-140.

The car feels totally sluggish and can only hit 3PSI of boost. Even at 3PSI its slower than usual, It struggles to merge into traffic. It's slow on the acceleration department but can keep up to speed once I get to it.

This morning I checked my coolant levels suspecting a possible head gasket issue. I had no coolant in the reserve tank. I topped it off and now will wait to see if the coolant "disappears".

 

^No coolant in the tank, or no coolant in tank AND radiator low.?

 

I'd start by checking all the intercooler hoses and clamps. I've see the one on the compressor outlet slip off and on before. Fredb

 

Checking the intercooler clamps is a good idea, although usually when they go it makes no boost at all.

The compression test numbers are consistent, which tends to indicate against a head gasket failure. Raw compression test numbers depend heavily on the tester that you're using, a leakdown tester would be more useful if you're looking at stuff in isolation.

Clogged cat sounds like a decent candidate to me -- pop it off and inspect it. Make sure to inspect both ends, I've had one where the front looked fine but the back was falling apart.

Why is the VVT "disabled"? Are you sure that setting is still correct? Is it flopped all the way over to max retard/max advance, or sitting somewhere in the middle?

Does it seem to drive normally off-boost? No misfires?

--Ian

 

Here's something else I forgot..

1) I found oil leaking out of the cold side of the intercooler pipes (from the intake manifold). I pulled the piping off the intake manifold and inspected inside the intake manifold- there's a ton of oil. Enough so that it shot out into the intercooler pipes, causing them to leak oil where they connect. I have a catch can running that is connected to all ports of the engine. The intake manifold should have minimum oil in it. I'm thinking the oil came directly from the engine.. Although my mechanic friend says that makes no sense.

2) There is a STRONG oil/gas burning smell from the car when I have the heat on. It smells like a rich mix of fuel mixed with oil. However, my AFRs have not changed one bit from when the car ran fine. It does not run rich during idle. Although it still reeks of gas-- this may be due to the catch can that is VTA. Not sure if this is a big problem.

2)The coolant was gone from the reserve tank. I had enough coolant in the intercooler. There isn't a physical leak as I haven't seen a puddle develop. I've refilled the reserve tank and will see if it evaporates.

3) Clogged cat? It was replaced with all my other turbo parts from FM. I did the install in May 2015. Does it still make sense to check a fairly new cat? This kind of makes sense as I'm experiencing a gas smell-- if I recall correctly, a cat should smell like eggs?

4) When I WOT, my turbo will spool at a "normal" rate, but my engine sounds like its bogged down. I can only describe it as a very low bellow noise, as in it's working really hard but not getting enough air/gas.. However, my AFRs are still running like they used to. So I have no idea... I'll try and get a recording of the sound when I go WOT. *Edit* So it actually sounds like the normal WOT sound, the engine creates a deep bellowing noise but the RPMs don't rise very quickly and I get very little power-- plus my turbo tops out at 3.2 PSI.

5) The reason I suspect a head gasket leak even though I've done a compression check is that I get white smoke from my tail pipe even after the car has warmed up. The car will blow white smoke when it's idling and warmed (...could be condensation as its cold here now). The white smoke is not noticeable when the car is in motion though.

6)When I say VVT disabled, I mean that in my Megasquirt settings, I've kept it off.

 

The oil didn't come out of the intake manifold, it came in through the intake, either through the cam breather or by leaking past the seals on the turbo. Do you have an appropriate pressure restrictor for your turbo oil inlet?

Do you still have the charcoal canister/etc installed?

Coolant in the intercooler? Is it W/A, or did you mean to type radiator?

Rotten eggs means you have sulfur building up in the cat, and when the car goes rich it's burning off as hydrogen sulfide. A clogged cat doesn't smell like anything in particular, the car just makes less and less power because it's getting more and more back pressure. If the core is coming apart, then it can change suddenly (either better or worse) as the chunks shift around.

When you say AFRs are fine, how are you measuring it? Wideband gauge? Is it running open loop or closed loop under boost? If you're in closed loop and not flowing air, then the ECU is just going to adjust the fuel down so that it still hits the target.

Condensation should be gone after the car is fully warmed up. If you're getting that, you want to do a leakdown test.

--Ian

 

Boost leak test, check turbo shaft play. Check all fluid levels and check for leaks.

I highly doubt it's a HG given your compression test, but if it were leaking coolant in the cylinders, the plugs will show it. Check plugs.

Post a datalog of behavior.

You said you have a known ground problem. Find and fix it. Get the Mazda electrical diagrams and check every factory ground location. Check = remove, inspect, clean, reinstall, torque tightly.

 

I'll get to all your questions tomorrow when I log everything. For now, I found a new symptom!

When I accelerate, I hear some sort of hissing noise. I think its a leak! It's coming from the turbo side. Is it possible that my wastegate isn't shut even though the actuator arm is fully attached? I'm about to spend some time on the car. Will find out..

I know it isn't the spooling of the turbo since the hissing noise can be heard as soon as I hit the throttle. The car has never spooled from idle to small throttle inputs, so I definitely think something is up with the leak.

The reason I don't suspect a leak is because my idle is perfect. Could a wastegate leak lead to normal idle?

 

A leaking wastegate would hurt spool, but given that the wastegate is open (and in some cases open to the maximum amount) at WOT, it's unlikely to reduce your max boost to just a couple psi. It's also unlikely it would make a hissing sound.

OTOH, a boost leak between the turbo and the throttle body would make a hissing noise, and would reduce boost substantially. Since you're running an MS3, I assume the car is running with speed/density, MAP-based control, rather than using a MAF? In that case, a leak between the turbo and the throttle body will make no difference to the operation at idle, because the MS3 doesn't care if intake air comes in through the filter and turbo or through a hole in the intake plumbing somewhere.

--Ian

 

Thanks to everyone's suggestions I think I've finally figured it out..

The four bolts connecting the down pipe to the exhaust had sheared off. The downpipe and exhaust are not fully seated on each other. This explains the fact that I smell oil/gas all the time and that my idle is normal. It also explains why my boost doesn't go above 3PSI. Also, when I think about it, I used to here "tink, tink, tink" sounds when the car was warming up. I think it might have been these bolts that were under shear pressure before they went-- I don't hear that sound anymore.

But, as I type this explanation out.. What doesn't make sense is that my sound levels didn't go up. The car doesn't sound louder than it was ever before... Hrm.

Here are pics of the downpipe..

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This is what it looks like from above

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Now a few things I have no explanation for that may be contributing factors..

First glance it looks like a leaky valve cover as I have oil coming down the side. But if you look at the oil cap, it looks like the oil comes from there.. I've reseated the valve cover a number of times and am pretty sure that it isn't it (I used a no-name gasket for a week, realized I was leaking then purchased a Mazda one.. It sealed fine).

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Finally, my catch can has a milky fluid in it. I'm guessing its from contaminated oil hitting a certain temperature and having the particles become solid. Anyone else experience this?

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I wonder how 4 bolts that attached the downpipe to the exhaust managed to shear off. Is this a common thing?

 

A leaking downpipe doesn't explain your lack of boost.

The leaking exhaust manifold pic is bad though, need to fix that, and that could cause low spoolage. I'd still do a boost leak test no matter what.

 

My buddy's Msm upgraded to big turbo running 22psi leaked out of his oil filler cap. Got a new none Mazda speed cap said it helped.

What boost where u hitting before?

 

Yeah, an exhaust leak before the turbo will make less boost. An exhaust leak after the turbo makes MORE boost.

That said, you need a pretty big exhaust leak to seriously affect max boost. Consider that at full boost your wastegate is most if not all of the way open, creating roughly a 1" diameter pipe that bypasses the turbine. Turbines make excess power relative to the needs of the compressor by design.

--Ian

 

I had a leak in a similar place to the OP on my GT3271, and it got super laggy on me and would only make about 5 PSI boost at 5,500 or so. I broke an exhaust manifold stud and the ones on the front had vibrated loose. Black soot everywhere. Funny thing it didn't really sound that loud, you'd think an exhaust leak that bad would be loud. No idea why it wasn't.

 

I'm not only getting boost lag, but I'm getting a huge loss of power.

I'm set to boost at 11PSI and can only hit 3PSI max now.

So the down pipe connection doesn't explain my symptoms?

...bah...