EFR 6758: Where the heck is my spool?
 

Looking at all those marvelous spool data from other members I wonder where my magic unicorn EFR spool ist hiding. I'm only hitting 200 kpa at 3,800 RPM. It really feels like an old-school turbo ("nothing.....nothing...still nothing... BANG").

I'm running a VVT engine, MS3-Pro, 750cc EV14s, Walbro 190HP. Full 3" exhaust system, 2.5" intercooler piping. Exhaust manifold is a welded log manifold; intake manifold is a squaretop mani.

If I do a pull in 4th or 5th gear from 2,000 RPM boost is only slowly building. At first I thought I was given the wrong EFR 6758 A/R housing (0.85 instead of 0.64), but when I installed an EFR 6258 (0.64) the spool was identical :( Some KPA data from the pulls:

RPM 6758 6258
2500 112 110
3000 130 131
3500 160 164
4000 227 235
4150 250 250

Even my tuner says I should hit 200 kpa at 3,000 (as others with a similar setup do). Things I tried:
- switching between external and internal BOV - no effect
- running with the wastegate signal line unhooked and wastegate wired shut - no effect
- 100% EBC duty cycle - no effect

I'll temporarily bridge the intercooler next, and run a pipe directly from the compressor outlet to the intake manifold to see whether my intercooler is holding me back. Beside that I have no idea what else to do. I could check for boost leaks, but I'm certain I don't have any leaks. Oddly enough when driving on the highway and touching the throttle beyond 4,000 RPM boost builds INSTANTLY. So there is no boost lag at higher RPMs. But down low it just takes forever to spool and build significant boost.

Is my log manifold holding me back? Or am I expecting too much from the EFR turbo?

Can you please post tune and logs from your pulls?

wastegate might be stuck and not fully closing. had this happen on several of the efr's

pics of your manifold? logs aren't the best but normally spool up alright.

any exhaust leaks? post turbo leaks slow exhaust down too.
Being that the change from a 6758 to a 6258 didn't change anything its safe to say its a supporting mod of some kind limiting performance.
Do you have a cat converter?

i checked the flapper, mechanically it completely engages (shuts). I even did a run where i strapped a wire to the wastegate door to hold it shut. Also, it's probably unlikely that both wastegates on both EFRs were stuck. FWIW, both WG actuators had their rods checked for non-binding as well.

https://cimg1.ibsrv.net/gimg/www.mia...ec03ecbd08.jpg
it pretty much looks like an Artech manifold. I have a full 3" exhaust system with V-bands (turbo - DP, DP - midpipe, midpipe - exhaust tip) and a 200cpi metal cat. No exhaust leaks (I tried to hold it shut with a rag while the engine was running.

You'll need to post logs at least since clearly you already ruled out all the obvious stuff

yeah, having just went through your build thread and the stuff here it sounds like a tune issue.

Post a log and your tune so someone can read it. (I don't do MS, sorry)

How much time did you spend tuning the VVT table? 3000rpm sounds like a point that VVT angle changes in most tunes.

yeah will do when I leave work. Thanks a lot in the meantime

Idk I think it is your EBC settings / EBC related.

except the part where he clearly WIRED THE WASTEGATE SHUT
so it should boost insanely fast

That's what I mean, like has it on inverted? So he would be holding it open?


Just guessing. Need the tune to do anything useful and 18psi would know better than me.

No he physically wired it shut. Not ebc. As in held it shut with wire.

yep, that's right I removed the wastegate actuator and tied the wastegate flapper shut with a wire.

anyway, here's my tune and a log from when I ran several pulls with the wastegate signal line unhooked. This gives maximum spool (verified by having the same spool-up with the wastegate hardwired shut). Temps were high (around 30-35° C). With cooler ambient temps spool comes on a bit earlier.

https://cimg8.ibsrv.net/gimg/www.mia...99b8693d57.png
https://cimg0.ibsrv.net/gimg/www.mia...34bf8f64f5.png

for some reason my VE table is funky @ 40 kpa & 5000 RPM, i know. And for some other reason the VE numbers doen't increase with boost

If you have an intake pressure referenced fuel system, your VE numbers will stay fairly flat with boost. only absolute pressure system (as in NBs in the US for example) will have VE increase with MAP.

My guess would be a huge boost or exhaust leak somewhere.

Sounds like a boost leak. (Turbo is pushing the air it normally would, but its being lost through the leak).

is the exhaust housing properly tightened down to the chra

Yes, no exhaust leaks anywhere (verified by holding the exhaust closed with a rag; also there is no black carbon build-up at the V-bands). I'll build something to test for intercooler leaks, but I doubt that's the case.

housing being loose may not leak, but if the turbine is even 1mm off or not seated it could result in terrible spool

No, it's tight. Also, it's probably unlikely to happen on two EFRs at the same time. I'd rule out the turbo itself as a cause.

No exhaust leaks? Two different turbos? Your motor is gravy?

All things being equal, have you tried a new tuner?

I would be interested to see compression and leak down test results.

No, cuz I'm the tuner :-D I talked to the owner of the shop where I got my turbo kit from. He suggested I add another 7* on top, which I of course declined - I dont' think my engine will live very long running 14* of timing at 250 kpa and RON95 fuel.

engine is freshly built with Wiseco rings and Supertech pistons. Break-in period was 1.500 km running N/A and the car ran strong. I then mounted the turbo kit and the lag of spool was apparent from the start. I really don't think compression or leak down are a problem, since the engine was healthy right before and after the rebuild.

This wouldn't be the first engine to shit the bed upon first startup. You have to rule it out, it's part of the game.

Have you tried doing a pull with the mid pipe removed from the car? This way you can either eliminate that being the issue, or figure out something in that is clogging and causing the problem.

Interested to see flow through the intercooler. ...How can this be tested easily. Fill with water then dump? Hard to quantify data, but at least you could see if it either empies fast, like instantly, or slow.

If you had the turbine speed sensor this might be a good troubleshooting tool as well. I am not saying you should spend the money for the hell of it, but if it's something you want to install in the future, now might be a good time.

my plan of attack is to first replace the intercooler with a straight 2.5" pipe and test how it reacts. This will rule out any negative effects by the IC.

I then will use said pipe and a few silicone elbows, and run a direct connection from the compressor outlet to the intake manifold. This will test for adverse effects from the IC piping.

then I will do a run with the shortest possible exhaust (maybe DP-only, or midpipe) to rule out the exhaust.

however, I'll be gone til Sunday night due to work :(

I would do a run without the mid pipe. As I am guessing that is where your catalytic converter is at, and that is what I would think would be clogged.

I would suggest you take the car to a dyno and properly tune it instead of trying things yourself with advice from your tuner.

Last time I let a tuner hold the car to 'figure it out' I got it back a month later with hardly anything fixed.

My checklist;

-Poor compression due to rings / valves / seats
-Plugged cat
-Timing is off either mechanically or set incorrectly
-Check for fluids around the spark plugs, I had a bit of water in one once and the car ran like balls.
-Plugs gapped to high?

In this image the green line, what is it? I find it strange that it says a max of 80% and drops while spool is almost at peak. Is that EBC dutycycle?

Thats normal for EBC. Hold the set max until you get close to boost target, then drop to control.

So is the wacky variation in RPM due to spark cut? I didn't use PWM PID for my EBC so I guess that's why it looks strange to me.

If you didn't use PWM how did you control the solenoid....

RPM variation is probably boost cut.

I just used the boost duty table. I didn't adjust any of the values in the PWM PID value set, I just use Open-loop. I am also on MS2 so it may be different.

Derp. I meant to say PID, not PWM.

Got it

Man that sounds like a frustrating problem. Cam timing a tooth out perhaps?

are you using the bypass valve on the EFR or a BOV? This seems like a potential issue.

I'm siding with the people who are saying a boost leak. Probably not in the intercooler, it's more likely in the couplers and plumbing from turbo to IC and IC to throttle body. I had a case like this once.

BIG boost leaks will give you no boost at all (or maybe 1 psi at 6000 or something like that). Teeny boost leaks are irrelevant. small-to-medium size leaks are rare, but can do this. In my case it looked like this:

http://www.codrus.com/miata/fm2r/boost-leak.jpg

--Ian

What does this mean, and what are the issues? Learn me please.

its possible the bypass valve or the bov depending on which is being used is leaking and causing the slow spool. Just a thought. They can crack open early and youll lose boost through it.

Had a few pin / slightly larger size ones in my ic pipe.
Welded them up and went from 7psi to 11.8.

So they can build up. unless i also had a leak from my tubing but hey. no idea.

Quick update since I'm drowning in work: last night I did a test run with the intercooler bridged. Using brand new silicone coupler and a 2.5" alloy tube I ran the turbo directly to the throttle body. Spool was unchanged. In the process I also did another back to back testing of the internal BOV vs the GFB DV+ -again this had no influence. 200kpa at 3850 rpm, while it took an entirety to go from 100 kpa @ 2000 rpm to 140 @ 3350. Beyond that point the spool really kicks in.

due to work I won't be able to do much more testing before the weekend.

That wacky rpm line looks like my shitty logs of the junkyard motor i threw in my car.
Im around 20-30% leak on cyl 1/3/4, cyl 2 is 40-45%. Also misfiring at times on cyl 2.

Im not burning oil, but she vents out the crankcase like crazy....
I compared all my logs on my current motor to my previous one. All logs since i threw in the motor have the jagged rpm. Prev motor was perfect smooth.

I have a feeling its caused by cyl2 not providing enough power compared to the rest, also car starting to shudder like crazy, as motors no longer balanced.

What RPMs do you mean? That jagged line at the end of the screenshot is overboost protection engaging. The spool-up RPMs are linear.

my eyes are dud.

quick look made them seem up-down slightly. considering the starting rpm jumps - which my car does.
i.e. for everyt 100rpm my car jumps it then drops 10 on 1 frame, making a slightly jagged climb.

If there are no bigger leaks in the pressure line I think it has something to do with the exhaust manifold.
I had a log type manifold at first to. Runs great with the small garrett turbo.
But with the change to the EFR 6258 it was not as good. (I have no logs and this is years ago)
Then I build a pulse-charging manifold and had 200 kPa at 3200 rpm.
But I had the air filter (open type) behind the radiator. So the intake air was very hot.
Changing this to a cold air intake pushes the spool. So I am now at 200 kPa@3200 rpm.

By the way: Your ignition is very late. Why do you run the engine with RON95 and not with RON98? I think my igintion with boost is 10° earlier... (But the later the ignition the better the spool. An earlier ignition angle will give you much more power but less spool and less exhaust temperature.)

So I checked the intercooler pipes for leaks - nothing. No visual damage, and held 1.5 bar positive pressure without any losses. So that rules out the IC system and BOV as possible causes.

two reasons: first, I completed the build 2 days before I went on a 1100 km trip hooning through the dolomites at 35 degrees. Down there they don't have any RON98 ANYWHERE. I therefore didn't want to take any chances and ran a safe map. Second, knowledgeable folks like Savington recommended to remove timing from my original map.
I built myself some det cans and will tune timing with those later on.

Did this ever get figured out?

yes. check his build thread

Well, sort of. I'll still try another manifold though. The Kraken cast manifold seems to be better flowing, similar to TSE's manifold, while being affordable for us mere Europeans.

So I finally but the bullet and bought a Kraken manifold. Installed it 2hrs ago. fuck me, this thing MOVES! It must have been the crappy log manifold as Tim said. The shorty tubular manifold offers a tremendous difference in response, spool-up and overall driveability. Since this is Miataturbo I'll soon provide catalogs to back up my subjective opinion, but this manifold is like night and day

I just installed a Kraken manifold and efr6258 and with open loop boost control set to 200-210kpa here is my spool:

4th gear pull, starting at 2700rpm

3000rpm - 8.3psi
3200rpm - 10.8 psi
3400rpm - 13.1 psi
3573rpm - hit target of 14.5 psi 201 kpa.

looks reasonable? how does yours compare now that we have the same setups?

Your welcome :skid:

Most of the data on the spool thread has runs that start at 2k. Can you do a run there for direct comparison?

Did you check spool diferences between 6258 and 6758?