Engine cutting out under load/boost - 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 08-25-2011, 06:19 PM   #1
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default Engine cutting out under load/boost

So finally got my car running on megasquirt after problem after problem etc.
So anyway after doing the basic settings ie spark and constants i went out for a spin. Figured with the base tune itd drive and at worst knock. So i went out and was able to accelerate just fine but when i went wot or boosted over 4 psi my engine cut out, tach died and ignition basically cut off for a second
So I checked overboost setting and set it for 255. Same thing happens
Changed the constants a lil more and once again same thing.
Went through all the other settings and none of the other hard cuts seemed like they should be happening

Im basically running a base tune for a 90 miata but it has 1.8 engine.
Doubt it makes a huge difference though.

Someone mentioned dwell when i was searching but it didnt seem to me that with a base tune my engine would cut out under boost. Maybe knock at most
And to me it still seems like im hitting the overboost protection even though its basically off at 255.

Idk
braaat is offline   Reply With Quote
Old 08-25-2011, 06:24 PM   #2
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

What's on the car? Any relays or fancy stuff? Are you logging?
hornetball is offline   Reply With Quote
Old 08-25-2011, 06:53 PM   #3
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

stock 1.8 injectors, turbo, walboro 188 fuel pump and begi fpr. No fancy stuff relays, boost solenoids etc.

No im not logging. Ill go give it a shot though

Last edited by braaat; 08-25-2011 at 09:22 PM.
braaat is offline   Reply With Quote
Old 08-25-2011, 07:52 PM   #4
I'm Miserable!
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,869
Total Cats: 3
Default

get a data log
Techsalvager is offline   Reply With Quote
Old 08-25-2011, 09:16 PM   #5
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

Will this work?

Im guessing every time that red line splits the graph my ignition is being turned off??
Attached Thumbnails
Engine cutting out under load/boost-miatacutsoff2.png   Engine cutting out under load/boost-miatacutsoff.png  

Last edited by braaat; 08-25-2011 at 10:02 PM.
braaat is offline   Reply With Quote
Old 08-25-2011, 09:57 PM   #6
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

Heres a prime example with spark angle now
Attached Files
File Type: msl now.msl (220.2 KB, 118 views)
braaat is offline   Reply With Quote
Old 08-25-2011, 11:43 PM   #7
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

So I went in for kicks and giggles and dropped the rev limit real low to mimic whats been going on then went in and lowered the over boost protection and determined it was boost related. Ended up disconnecting the map and car ran great. So I decided to raise the overboost to 20 psi this time in tunerstudio and car ran much better but still not perfect.

So my question is, why would a map sensor read 15psi high.
braaat is offline   Reply With Quote
Old 08-26-2011, 12:31 AM   #8
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,775
Total Cats: 1,106
Default

Those red lines are when your MS is loosing sync. What are your grounds like?
shuiend is online now   Reply With Quote
Old 08-26-2011, 02:11 AM   #9
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

which grounds like the grounds for the motor. They always worked before
but yea megasquirt is definetly turning on and off when the car starts bucking
which grounds are in question
and if it was a ground how come when I disconnect the map sensor the car works flawlessly
and after reviewing my logs the map appears to be working flawlessly
wtf....idk
braaat is offline   Reply With Quote
Old 08-26-2011, 02:27 AM   #10
Senior Member
iTrader: (2)
 
Join Date: Aug 2005
Location: Granbury, TX
Posts: 567
Total Cats: 1
Default

Quote:
Originally Posted by braaat View Post
which grounds like the grounds for the motor. They always worked before
but yea megasquirt is definetly turning on and off when the car starts bucking
which grounds are in question
and if it was a ground how come when I disconnect the map sensor the car works flawlessly
and after reviewing my logs the map appears to be working flawlessly
wtf....idk
I had this exact problem pretty much. Cleaning/tightening/more grounds fixed it right away.

But not saying that's for sure your problem, however its deff something to check anyway.
greenday3437 is offline   Reply With Quote
Old 08-26-2011, 02:42 AM   #11
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

Hell yea. Definitely worth it to check em.
Your car worked flawlessly with the map disconnected?
braaat is offline   Reply With Quote
Old 08-26-2011, 02:07 PM   #12
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

Here's the bottom line. You've got electronic noise. It is sometimes causing resets. Sometimes, it doesn't go so far as a reset (you can see lots of spikes in MAP and CLT in your logs without the red lines).

When noise is present parameters go haywire.

You need to get rid of the noise.

Focus on three areas:

1. Grounds. Pull the grounds. Wire brush them. Re-install and torque. Pull the coil bracket. Wire brush that too. Re-install and torque. Make sure your ground for ECU power is relatively isolated from grounds of things that generate a lot of noise (like a radio). The closer to stock wiring, the better.
2. Power. As with grounds, make sure your ECU power is relatively isolated from noisemakers. Anything with a coil is a killer (relays, solenoids, ignition, electric motors). Headlights? Radio? Again, if you've preserved your stock harness, you're better off.
3. Electro-Magnetic Interference (EMI). Make sure your ECU is protected from EMI. Hopefully, you didn't hack the ECU harness much. An MSPNP is ideal from this standpoint. Make sure you have the metal cover on the ECU and that the metal cover is grounded to your frame (and NOT grounded to the ECU power ground).

The more you kept your OEM harness intact, the better. Beyond a general cleanup and inspection, the next step is to carefully examine your logs and try to correlate the reset events to something external.

In my case, I was able to correlate resets to reductions in the MAP signal through my WI setpoint. This then tied into when the WI relay would depower and generate a flyback voltage. By moving my flyback diode outside of my ECU, I eliminated the resets. This is the kind of detective work that might be needed.
hornetball is offline   Reply With Quote
Old 08-27-2011, 12:36 PM   #13
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

Cleaned all the grounds.. Tried running a ground from the battery to ecu and from the battery to engine. Tried disconnecting the alternator. Nothing
braaat is offline   Reply With Quote
Old 08-27-2011, 01:00 PM   #14
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

did i mention that the car runs flawlessly on stock ecu.

is the megasquirt demanding more than the stock ecu?
braaat is offline   Reply With Quote
Old 08-27-2011, 01:20 PM   #15
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

Quote:
Originally Posted by braaat View Post
did i mention that the car runs flawlessly on stock ecu.

is the megasquirt demanding more than the stock ecu?
That's good. You're narrowing the possibilities. I assume your able to swap the stock ECU . . . which means that stock wiring is mostly in place.

I was really curious about your setup . . . stock injectors + fuel pump + FPR + MS. Looks like your asking a lot of the stock injectors . . . although that's not the problem here.

What type of MS is this? MSPNP, DIYPNP, other?
hornetball is offline   Reply With Quote
Old 08-27-2011, 07:31 PM   #16
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

seeing as the car is running so well under boost with the map disconnected and the seller of the mspnp telling me the ms works, i decide to out of curiousity input the values of boost in place of the atmospheric kPa basically replacing 90 with 120kPa and and 101 with 139 and so on. And car runs as flawlessly as it did with the map disconnected except now it can idle.

Basically it was my tune. I have a fpr on my return fuel lines so the ecu pressure meant diddly and this ^ was the only way to get it to run. But damn I feel stupid getting caught up in this being a grounding or noise issue i never even considered it being my tune. I just never realized ms would kill the ignition on a shitty tune. At least my cars well grounded now though.

Last edited by braaat; 08-27-2011 at 10:45 PM.
braaat is offline   Reply With Quote
Old 08-28-2011, 12:19 AM   #17
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

I'm surprised. I knew that the basemaps you were running would not work well with a FPR -- they were designed for a stock engine. But, I would not have expected that to result in dropped syncs and data spikes.

Hmmm . . . . Well, glad you're running better. Keep us advised on progress. Also, how about doing a build thread?
hornetball is offline   Reply With Quote
Old 08-31-2011, 12:55 AM   #18
Newb
Thread Starter
 
Join Date: Jan 2011
Posts: 22
Total Cats: 0
Default

Yea definitely should start a build thread especially with me having to pull the motor to replace some oil pan seals. Tried doing it with the motor in car and its still leaking only the back one now tho.

Anyway I disconnected the fpr and those base maps ran pretty smooth untill I started running straight downpipe and now I have some raw boost creep. Like 12lbs with the wastegate actuator bar completely disconnected. But the car pulls like a monster till it cuts out. I swear it'd stay with my 600 if it kept pulling lol. No need for fare warnings on blowing my **** up I know.. I just wish my **** wasnt leaking oil all over the place so I could focus on tuning.
braaat is offline   Reply With Quote
Old 08-31-2011, 01:40 PM   #19
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

Now that you're running better, you should do another log. I'll bet there will still be some sync drops and data spikes. I think you may have had two problems (three if you count the oil leaks).
hornetball is offline   Reply With Quote
Old 08-31-2011, 03:46 PM   #20
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

Resets...could be firmware corruption.

Do you get errors when you connect to the controller?
gospeed81 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 58 Yesterday 10:04 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Got bad Crank Angle Sensor and Random Misfire codes, but runs fine. Greasyman General Miata Chat 2 09-28-2015 11:44 AM


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 05:20 PM.