My Speed 3 isn't making power.

[Alexey]

So, I have a 2008 Mazda 3 MPS with a built engine — Gen2 pistons and Eagle rods. It's FBO with downpipe, HPFP, intake, FMIC, and so on. Stock turbo, intake manifold, and exhaust manifold also stock.

It's a pretty typical setup that should be doing 100–200 km/h in around 12–13 seconds and making about 300 whp. But unfortunately, after tuning, the car is only showing around 260 bhp on Virtual Dyno and does 100–200 in 17 seconds.

The car is tuned by Jast, and I trust him — he has many fast builds, including my Speed 6, which runs very well.

Logs look good — there's boost, timing, proper AFR, etc., but for some reason, the car just doesn't pull. I've checked the timing marks, inspected the intercooler, even removed the exhaust — still no clue what's wrong. I also swapped the turbo — took it from a friend whose 3 MPS runs 100–200 in 12.3 seconds — but nothing changed. I'm really stuck and would appreciate any fresh ideas.

Today I'm planning to try swapping the throttle body and checking the intake manifold.

[mituc]

What is your EBCS setup? How is it connected, where, what line size are you using and what EBCS is it?
Also, what BPV/BOV are you using?
I do not think your throttle body or intake manifold are the problem. A stock turbo flowing 250+ g/s of air at 70% WG duty is normal. Also you seem to be at a pretty good altitude/elevation, and the weather doesn't seem to be the coolest either...

P.S.: 60-100mph/96-160kmph in your log is around 6.9-7s. It's not bad, a stock 3MPS does 96-160kmph in 4th gear in about 7.8-7.9s, the slightly tunes ones go down to about 7.2s. So yours is not bad or broken, just needs a few things addressed and possibly needs re-tuning.

[Alexey]

What is your EBCS setup? How is it connected, where, what line size are you using and what EBCS is it?
Also, what BPV/BOV are you using?
I do not think your throttle body or intake manifold are the problem. A stock turbo flowing 250+ g/s of air at 70% WG duty is normal. Also you seem to be at a pretty good altitude/elevation, and the weather doesn't seem to be the coolest either...

P.S.: 60-100mph/96-160kmph in your log is around 6.9-7s. It's not bad, a stock 3MPS does 96-160kmph in 4th gear in about 7.8-7.9s, the slightly tunes ones go down to about 7.2s. So yours is not bad or broken, just needs a few things addressed and possibly needs re-tuning.

BPV CorkSport. MAC solenoid, line diameter is around 4mm. Сonnected like this:

VcAAAgFm_uA-1920.jpg (17.02 KiB) Viewed 3745 times

Regarding the weather, it was around 18°C at the time the logs were recorded. The FMIC is a CX-Racing unit.

My 6 MPS with a stock turbo did 100–200 km/h in 15 seconds, but this lightweight 3 MPS with full bolt-ons is running close to stock times (for a 3 MPS). As far as I know, a stock 3 MPS does 100–200 in around 18 seconds.

[Alexey]

As expected, the throttle body didn't help with the issue — but I was still hoping it might

[mituc]

BPV CorkSport. MAC solenoid, line diameter is around 4mm. Сonnected like this:

Check the MAC valve and see if that cap it has did not fall off. If it did then replace it and on the new one use some duct tape all round to force that cap to stay in place. This is one of their weak points but it's an easy fix.

[Alexey]

BPV CorkSport. MAC solenoid, line diameter is around 4mm. Сonnected like this:

Check the MAC valve and see if that cap it has did not fall off. If it did then replace it and on the new one use some duct tape all round to force that cap to stay in place. This is one of their weak points but it's an easy fix.

I already checked the valve, even tried the one from my Speed6 — no difference. I'm thinking of disconnecting the exhaust from the downpipe in the next few days and doing a test run. Logs look fine, but the car just doesn't pull — it's like hitting a wall.

[mituc]

What you can do is to disconnect the hose between the compressor housing and the wastegate actuator (disconnect it from the wastegate actuator and cap it with a screw) and make a test at like 50% throttle. This way you will know if the problem is on the exhaust or if it's on the wastegate actuator/EBCS. Be very careful, if the problem is not on the exhaust side you will get a lot of boost relatively quick if you press the acceleration too hard, so be mindful during this test.

[Alexey]

What you can do is to disconnect the hose between the compressor housing and the wastegate actuator (disconnect it from the wastegate actuator and cap it with a screw) and make a test at like 50% throttle. This way you will know if the problem is on the exhaust or if it's on the wastegate actuator/EBCS. Be very careful, if the problem is not on the exhaust side you will get a lot of boost relatively quick if you press the acceleration too hard, so be mindful during this test.

Looking over the logs, I’m seeing exactly the boost I’d expect across the whole range. I’ve also got logs from another car with the exact same setup as mine — I’m actually running his turbo right now, and I’ve swapped over to the BL transmission (from my buddy’s Gen2). If anyone’s interested, I can post both sets of logs side by side.

Thing is, my logs look perfectly fine… but he’s running 12.2 while I’m stuck at 16.3. Another friend just finished his MPS3 build on the stock turbo with a bolt-on setup like mine, and he managed a 12.4.

Worth noting — all of us are tuned by the same tuner, so the calibration side should be consistent. That’s why I’m trying to figure out what’s holding my car back.

[Alexey]

Small list of what’s been done so far in the search for the issue

Things already tried:
Replaced MAF
Replaced ECU
Replaced O2 sensor
Replaced bypass valve
Checked timing marks, trigger wheels, and valve clearances
Ran the car with the exhaust removed, only on downpipe
Swapped in a turbo from a proven car
Swapped in a transmission from a proven car
Intake manifold inspected
Throttle body replaced
Intake valves cleaned
Intake system pressure tested

What hasn’t been done yet:
Ignition coils
Crankshaft and camshaft position sensors
Injectors

At this point, the only original part left in the car is the engine wiring harness — all the accessories/bolt-ons are fresh from Japan.

[mituc]

Any recent logs after all this work was done?