Stock MSM -- insane turbo lag on shift
#1
Stock MSM -- insane turbo lag on shift
xposted on m.net
Alright, because I'm a masochist I went and bought an MSM.
One problem.. there's a ludicrous amount of turbo lag between gears. I've only run ball bearing turbos before and even on an NB with a GT3071 there's less lag.
I've read mazda-speed archives, m.net, MT, grassroots forums, and any other article I could find about the various ECU-related issues with the MSM. I understand there are three major problems:
1) The Bog.
2) The "lean spot" as it's referred to on m.net
3) The ECU just freaking out and pulling timing or fuel for some reason.
I can't find any actual technical information on what is happening or why for these, just people who don't know what's going on taking random guesses. Further, I can't find any descriptions of the behaviour when #2 or #3 is happening, only "The Bog".
I know it's not the bog. I spool around 4k reliably (which is pretty damn late IMHO) and don't have a sudden burst of power at 5500rpm.
I'll be calling FM tomorrow to discuss what the o2 clamp is actually solving and if that would solve this issue. I have another thread pulled up somewhere about how the o2 clamp in conjunction with a modification to the WOT switch on the TPS fixes random ECU freak-out lean condition somethings for WOT transitions, but I don't know if that's even my problem because I can't find a description of the driving experience.
Setup -
2004 with no power-adders.
94k miles.
Inconel studs, AOS check valve, rebuilt turbo (didn't need it, just while I was in there)
Symptoms -
Lumpy powerband, power doesn't really seem to come on until 4k or so and it's a huge slingshot.
Huge, huge delay in boost if I shift like a sane person. Akin to being at 2k RPM in second gear and flooring it, waiting for around 4k to hit and power to come on.
If I shift like a Honda kid yelling "POWERSHIIIIFT" or "NAAAWWWWSSS" this delay is minimized.
Ideas -
Could be that it's just a journal bearing turbo and there's a stupid amount of lag.
Could be this mysterious "lean condition" I've read a lot about.
Alright, because I'm a masochist I went and bought an MSM.
One problem.. there's a ludicrous amount of turbo lag between gears. I've only run ball bearing turbos before and even on an NB with a GT3071 there's less lag.
I've read mazda-speed archives, m.net, MT, grassroots forums, and any other article I could find about the various ECU-related issues with the MSM. I understand there are three major problems:
1) The Bog.
2) The "lean spot" as it's referred to on m.net
3) The ECU just freaking out and pulling timing or fuel for some reason.
I can't find any actual technical information on what is happening or why for these, just people who don't know what's going on taking random guesses. Further, I can't find any descriptions of the behaviour when #2 or #3 is happening, only "The Bog".
I know it's not the bog. I spool around 4k reliably (which is pretty damn late IMHO) and don't have a sudden burst of power at 5500rpm.
I'll be calling FM tomorrow to discuss what the o2 clamp is actually solving and if that would solve this issue. I have another thread pulled up somewhere about how the o2 clamp in conjunction with a modification to the WOT switch on the TPS fixes random ECU freak-out lean condition somethings for WOT transitions, but I don't know if that's even my problem because I can't find a description of the driving experience.
Setup -
2004 with no power-adders.
94k miles.
Inconel studs, AOS check valve, rebuilt turbo (didn't need it, just while I was in there)
Symptoms -
Lumpy powerband, power doesn't really seem to come on until 4k or so and it's a huge slingshot.
Huge, huge delay in boost if I shift like a sane person. Akin to being at 2k RPM in second gear and flooring it, waiting for around 4k to hit and power to come on.
If I shift like a Honda kid yelling "POWERSHIIIIFT" or "NAAAWWWWSSS" this delay is minimized.
Ideas -
Could be that it's just a journal bearing turbo and there's a stupid amount of lag.
Could be this mysterious "lean condition" I've read a lot about.
#3
You're describing the lean spot. I refer to it as the "hesitation" in order to differentiate it from the "bog", which occurs when moving from a stop and refuses to accelerate (feels like you're setting off in 3rd).
The solution, as many will shortly tell you, is to move to a stand alone ECU. The stock ECU is dog's *****. Megasquirt is the preferred ECU in these parts. While you're in there do injectors and an EBC solenoid so you can run more boost with better control.
The solution, as many will shortly tell you, is to move to a stand alone ECU. The stock ECU is dog's *****. Megasquirt is the preferred ECU in these parts. While you're in there do injectors and an EBC solenoid so you can run more boost with better control.
#7
It's the lousy stock ECU. I just today ordered a MaxxECU for my MSM. New in the Miata world, but huge in big HP turbo applications on many other cars in Europe. Supported in the US on MSMs by Brett Willett, who does a lot of remote tuning on Megasquirt turbo Miatas, including MSMs. Lots of reasons I picked it over a Megasquirt, but Brett was one of the big reasons.
#10
I think it's not more popular or common just because Brett is the first to support it and tune it for Miatas, including building the harness and such for those of us not saavy enough to DIY. He's installed and tuned the first one in person in TX. The MaxxECU is Swedish, and I don't think they've paid much (any) attention to the US market, nor done a bit of marketing in the US. Given my long background with Saabs I kind of have an affinity for Swedish engineering. They seem to spend the long winter nights thinking about how to do things well. And Swedes seem to be far better engineers than marketers in my experience working for a Saab dealer back in the day! So it makes sense to me
#11
You're describing the lean spot. I refer to it as the "hesitation" in order to differentiate it from the "bog", which occurs when moving from a stop and refuses to accelerate (feels like you're setting off in 3rd).
The solution, as many will shortly tell you, is to move to a stand alone ECU. The stock ECU is dog's *****. Megasquirt is the preferred ECU in these parts. While you're in there do injectors and an EBC solenoid so you can run more boost with better control.
The solution, as many will shortly tell you, is to move to a stand alone ECU. The stock ECU is dog's *****. Megasquirt is the preferred ECU in these parts. While you're in there do injectors and an EBC solenoid so you can run more boost with better control.
Have fun, the rest of you.
#12
http://www.turbos.borgwarner.com/fil...ical_brief.pdf page 35
There are BW drag race specific turbos that are journal, but most of them use ball-bearings for improved spool.
#14
Garrett does too. https://www.turbobygarrett.com/turbo..._ball_bearings
"Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings."
I'm here to learn. What am I missing?
#15
From BW doc. "For this reason, the efficiency enhancement from a ball bearing system benefits the spool-up period" BW seems to think they increase spool-up.
Garrett does too. https://www.turbobygarrett.com/turbo..._ball_bearings
"Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings."
I'm here to learn. What am I missing?
Garrett does too. https://www.turbobygarrett.com/turbo..._ball_bearings
"Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings."
I'm here to learn. What am I missing?
So if you compare identical turbo's with the only difference being journal vs ball bearing, the dyno plot will look identical.
Most people say "spool" but mean "boost threshold". If you didn't, then disregard.
#16
When they say spoolup, they are not talking about boost threshold, but the "spool up" or transient response once you're at/past threshold.
So if you compare identical turbo's with the only difference being journal vs ball bearing, the dyno plot will look identical.
Most people say "spool" but mean "boost threshold". If you didn't, then disregard.
So if you compare identical turbo's with the only difference being journal vs ball bearing, the dyno plot will look identical.
Most people say "spool" but mean "boost threshold". If you didn't, then disregard.
How quickly boost increases after that threshold is what I was referring to as spool and that should be better with a ball bearing design.
If you reach target boost sooner with a ball bearing turbo why wouldn't that be reflected in a dyno plot? Peak power will likely be the same but shouldn't there be more area under the curve?
#18
correct
transient and threshold are two completely different things, and a dyno is done going WOT well before boost threshold, so unless you started the dyno well into the boost threshold (like say 4k rpm), you won't see transient
that's why you can't just make statements like "faster spool" without clarifying what you mean by it. 99% of the people out there don't know the difference and JB turbo's are looked down on for no reason
transient and threshold are two completely different things, and a dyno is done going WOT well before boost threshold, so unless you started the dyno well into the boost threshold (like say 4k rpm), you won't see transient
that's why you can't just make statements like "faster spool" without clarifying what you mean by it. 99% of the people out there don't know the difference and JB turbo's are looked down on for no reason
#19
My car has been running journal bearing turbos (old school T3/T04B/E) for years and I have zero complaints. The only time I've had problems with transient response is when I had a huge exhaust leak before the turbo.
Boost threshold is another thing. It's kind of funny how you can actually watch the boost gauge showing you the edge of the compressor stall region as your cfm climbs with rpm into the non-stall region at higher and higher pressure multipliers. My old T04B setup would make lowish (but still decent) boost at like 2k rpm and it would slowly climb to 18psi at 4000 or so. The T04E just suddenly comes alive like a 200 shot above 4k rpm and is kinda gutless below that. Stall region is more vertical in that compressor.
Boost threshold is another thing. It's kind of funny how you can actually watch the boost gauge showing you the edge of the compressor stall region as your cfm climbs with rpm into the non-stall region at higher and higher pressure multipliers. My old T04B setup would make lowish (but still decent) boost at like 2k rpm and it would slowly climb to 18psi at 4000 or so. The T04E just suddenly comes alive like a 200 shot above 4k rpm and is kinda gutless below that. Stall region is more vertical in that compressor.