Engine falls flat after ~6,800, can't figure this out! - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 05-22-2015, 02:37 PM   #21
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Well to be honest I'm just being careful with it as I broke a piston in half running 20 degrees advance about 3 weeks ago. Granted it was a stock 01 piston.

So I'm thinking I'm going to get the fuel richer, and try to get the virtual dyno going, and then start adding say 2 degrees of timing at a time and see what it shows. Does this seem reasonable?
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 02:56 PM   #22
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

While I agree that timing can be bumped up, I still don't think that's the answer to your torque nosing over so suddenly. But I too haven't tuned a SC BP at this level before.

Where's that VD plot showing torque curve
18psi is offline   Reply With Quote
Old 05-22-2015, 02:57 PM   #23
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

I downloaded the app, trying to figure out how to set it up correctly and how to use it. Google turned up some forum talking about how to use it, called miata turbo???
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 02:58 PM   #24
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

<p>
Quote:
Originally Posted by patsmx5 View Post
I downloaded the app, trying to figure out how to set it up correctly and how to use it. Google turned up some forum talking about how to use it, called miata turbo???
</p><p>&nbsp;</p><p>dont register there, they will give you a prostate exam, then eat your rectum.</p>
Braineack is offline   Reply With Quote
Old 05-22-2015, 03:00 PM   #25
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Looks like there's a ton of crap to setup! Is there an easy way to set it up quickly so I can go drive this thing? Does it really need engine specs, cam specs, etc?
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 03:05 PM   #26
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

no idea what you're reading, but VD takes all of 5 seconds (not even exaggerating) to set up
1)open vd
2) open log with it
3) do the 5 drop downs to dial in car's specs
4)?????
5) profit

or go do a pull in 4th or 5th on a level road from like 2k to redline and send me log
18psi is offline   Reply With Quote
Old 05-22-2015, 03:13 PM   #27
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Ha I had downloaded the wrong app.... I got it now.
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 06:07 PM   #28
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Update with more data and I found a problem.

First off, I live in Houston and I can't find a flat road where I can open the car up. I never really paid any attention till today, went where I normally go to tune and damn all the way there and there too it's hilly. Oh well, hopefully that doesn't skew stuff too bad.

Anyways, made a couple pulls for you guys to look at. All of them are 19-20 PSI depending on how high I reved it. AFR and boost show up at the bottom, which is nice. AFR with WI on will read about 0.5 Lower than actual BTW.

Red is 3rd gear, with water injection on, 14 degrees timing.
Blue is 4th gear, with +5 VE to the fuel table and +2 degrees timing so 16 degrees timing.
Green is 3rd gear, Water Injection TURNED OFF, and only 10 degrees timing with 11.0:1 AFRs. Was going uphill during this pull but oh well. Don't remember for the other pulls.



Datalog of the No Water Injection for the above graph in Green



The reason I turned off the water is I decided to test to make sure the nozzles are working, and I discovered something is going on, the system is loosing pressure when it should not. AKA, something in the system must be leaking. Previously I could shut the pump off and it would hold pressure for days. Now when the pump turns off, pressure drops in less than 2 seconds. I don't know if it's spraying in the motor or leaking somewhere, will have to look into this.

Now I'm tempted to start tuning it without the WI for now.

Thoughts? Throw timing at it? It needs something!
Attached Thumbnails
Engine falls flat after ~6,800, can't figure this out!-slow%2520miata_zpsulahtgoz.jpg   Engine falls flat after ~6,800, can't figure this out!-3rd%2520gear%2520no%2520wi_zpscecohpem.png  
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 06:49 PM   #29
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,105
Total Cats: 518
Default

VD assumes you are on a flat road. If you tune going down hill, it'll read higher. If you tune going up hill, it'll read lower. Granted, you should always be ignoring the numbers, looking only at the curve of the graph.

But, if you're comparing the changes you made, it needs to be the same gear, rev to the same RPM, on the same road. Pick a road sign going in one direction to floor it, then let off at predetermined rpm.

Also, you say you have a problem at 6800rpm, why are you giving us 2 dyno runs that don't even go to 6800rpm?\

Lasty, do you see how you're dropping power significantly after ~6200rpm? Do you think that gets better? No. You loose 20hp from ~6300 to 7000rpm, and it'll only get worse. Even if it doesn't, you'll be at 165hp by 8000rpm. Shift at 6500-7000, you'll be faster.

Using this calculator:

http://www.wallaceracing.com/calc-rpm-drop-shift.php

If you shift at 7000rpm, you'll end up anywhere from 4100 to 5700, granted, this is for 5-speed ratios. But you'll be right where your power is actually increasing. If you shift at 8000, you'll be anywhere from 4500-6500rpm, where you'll be loosing power.

Last edited by curly; 05-22-2015 at 07:03 PM.
curly is offline   Reply With Quote
Old 05-22-2015, 07:24 PM   #30
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Quote:
Originally Posted by curly View Post
VD assumes you are on a flat road. If you tune going down hill, it'll read higher. If you tune going up hill, it'll read lower. Granted, you should always be ignoring the numbers, looking only at the curve of the graph.

But, if you're comparing the changes you made, it needs to be the same gear, rev to the same RPM, on the same road. Pick a road sign going in one direction to floor it, then let off at predetermined rpm.

Also, you say you have a problem at 6800rpm, why are you giving us 2 dyno runs that don't even go to 6800rpm?\

Lasty, do you see how you're dropping power significantly after ~6200rpm? Do you think that gets better? No. You loose 20hp from ~6300 to 7000rpm, and it'll only get worse. Even if it doesn't, you'll be at 165hp by 8000rpm. Shift at 6500-7000, you'll be faster.

Using this calculator:

Gear Shift Drop Calculator

If you shift at 7000rpm, you'll end up anywhere from 4100 to 5700, granted, this is for 5-speed ratios. But you'll be right where your power is actually increasing. If you shift at 8000, you'll be anywhere from 4500-6500rpm, where you'll be loosing power.
Thanks for the feedback.

I posted those 3 because they are the only 3 I got. And more data is better usually. I've never used VD before either!.... I need to find a better road and do it as you say. I'll try to find a better spot like you say, that will help.

Yes the power is dropping too soon, I agree. But it's not consistent between runs!

If you look at the red vs green graphs, they are pretty similar at first, they part ways around 5,500. What I don't know is, why? Same car, same boost, same day, airflow through the motor should have been identical between those two runs, same fuel, etc etc, the ONLY difference (regarding the setup) is red had WI and 14 degrees advance where green had no WI and only 10 degrees advance and 0.5 AFR richer.

I don't know what this means, but the fact that they are making peak power at different RPMs is odd, right? I think this means the tune is part of the problem and it's not just the engine choking.

My guess is the WI is slowing the burn/basically retarding the timing.

Also I agree on the shifting to stay in the powerband. When the car was turbo it always pulled to 8K no problem though! See this vid of it when it was turbo for reference.

patsmx5 is online now   Reply With Quote
Old 05-22-2015, 07:26 PM   #31
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Also I can't ignore the fact that the car is making only 200 hp! Coding paradox ran a very similar setup and made about 315 to the wheels on pump gas. Our setups aren't identical, but I shouldn't be that far off!
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 07:29 PM   #32
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

Quote:
Originally Posted by patsmx5 View Post
Also I can't ignore the fact that the car is making only 200 hp! Coding paradox ran a very similar setup and made about 315 to the wheels on pump gas. Our setups aren't identical, but I shouldn't be that far off!
I wasn't gonna say anything since you're just setting the car up, but I'm glad you pointed out the large elephant in the room
18psi is offline   Reply With Quote
Old 05-22-2015, 07:31 PM   #33
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Yes something is off, no doubt. Thus why I'm here asking the experts for advice. I know this ain't a turbo but I expect more out of it. I'm gonna try hooking a timing light up, fixing the timing to say 10 degrees, and rev it high and see if it's holding constant. Also gonna pull and read the plugs again.
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 07:35 PM   #34
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

I keep looking over everything and also see nothing obviously wrong
whats the ve table looking like? is the car requiring less fuel past 6500?
18psi is offline   Reply With Quote
Old 05-22-2015, 08:22 PM   #35
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

VE Table:



If you look at the datalog from the last post, you'll see that I reved the engine to 7,000 RPM, AFR's were almost perfectly flat at 11.0:1, and Injector duty cycle was INCREASING the entire time, and at a fairly high rate (not flat) Thus if all those things are correct (constant AFR and increasing fuel) it must be breathing in more air/not choking. If it were choking and I kept adding fuel, AFRs would be getting richer but they are NOT!

I hit 57.5% duty cycle, these injectors flow 1,175cc/min at 60 PSI fuel pressure. That means with 11.0:1 AFRs I was burning 675cc/min of fuel. That's a lot. People make 300whp with 550s and 11:1 AFRs, I'm burning more than that!

And if that's true, where's my power!

Just pulled the plugs, I'll take pics and post in a sec, they look good to me. I'm no plug reading expert though, maybe some of you can take a look and give me your advice! Going to take pics now.
Attached Thumbnails
Engine falls flat after ~6,800, can't figure this out!-ve%2520table_zpsiybmop10.png  
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 08:25 PM   #36
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

Duty cycle may not have been increasing, duty cycle naturally goes up with RPMs as there's less time to hold the injectors open. Wouldn't pulsewidth be a much better gauge of fuel demands?
deezums is offline   Reply With Quote
Old 05-22-2015, 08:25 PM   #37
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

You not having tables past 7500K might have something to do with this

edit: I don't know what I'm talking about, I thought you were trying to rev to 8 for some reason?
deezums is offline   Reply With Quote
Old 05-22-2015, 08:39 PM   #38
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Quote:
Originally Posted by deezums View Post
Duty cycle may not have been increasing, duty cycle naturally goes up with RPMs as there's less time to hold the injectors open. Wouldn't pulsewidth be a much better gauge of fuel demands?
My understanding is duty cycle is the Percentage of Time the injector is open. So if duty cycle is 50%, you're injector is open 50% of the time, so you're spraying 50% of whatever it's rated at.

Pulse width is just how many milliseconds the injector stays open per cycle/event. I run sequential so they injectors fire once/cycle.

Here's the same log with PW and Duty cycle plotted.



Also here's pics of the plugs, let me know what you think please!

Plug 1



Plug 2



Plug 3



Plug 4
Attached Thumbnails
Engine falls flat after ~6,800, can't figure this out!-pulse%2520width%2520added_zpsxcswwxi9.png   Engine falls flat after ~6,800, can't figure this out!-plug%25201_zpsogjfvog1.jpg   Engine falls flat after ~6,800, can't figure this out!-plug%25202_zpstoygpuv8.jpg   Engine falls flat after ~6,800, can't figure this out!-plug%25203_zpsoswbbnqg.jpg   Engine falls flat after ~6,800, can't figure this out!-plug%25204_zpsqn16ank3.jpg  

patsmx5 is online now   Reply With Quote
Old 05-22-2015, 08:42 PM   #39
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 247
Default

Quote:
Originally Posted by deezums View Post
You not having tables past 7500K might have something to do with this

edit: I don't know what I'm talking about, I thought you were trying to rev to 8 for some reason?
I gotta fix that. Yes if I can get this fixed I am going to rev it to 8, it should make peak power just after 7K I believe, and not fall-on-its-face immediately afterward.
patsmx5 is online now   Reply With Quote
Old 05-22-2015, 09:02 PM   #40
Senior Member
iTrader: (5)
 
Join Date: Jul 2005
Posts: 715
Total Cats: 53
Default

Back to your water injection and the possible leak you are talking about. Is it possible it is suddenly dumping bunch of water at the higher rev which is causing the flat on its face issue?
bcrx7 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
1991 special edition with hard top full part out JC, NJ russian Miata parts for sale/trade 6 10-08-2015 04:01 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 12:44 AM.