MEGAsquirt A place to collectively sort out this megasquirt gizmo

AFR spike during acceleration

Thread Tools
 
Search this Thread
 
Old 03-11-2013, 08:07 AM
  #1  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default AFR spike during acceleration

Sometimes during a 3rd to 5th gear pull, I get a hiccup where it feels like the engine stalls for a very brief period. Sometimes this happens two or three times in a row over a one or two second period.

Attached is a log from this morning. Around 666 seconds, , I am in 3rd around 3800 RPM, I hit the gas and it starts to accelerate. PW spikes, followed by MAP and then I see RPMs dip and AFR spike for about two or three tenths. Then acceleration continues.

And ideas on why this might be happening and how can I correct it?

Thanks,
Travis
Attached Thumbnails AFR spike during acceleration-log_capture.jpg  
Attached Files
File Type: msl
2013-03-11_06.57.34 - Copy.msl (150.8 KB, 157 views)
File Type: msq
travisb_20130311.msq (40.3 KB, 146 views)
travisb is offline  
Old 03-11-2013, 08:26 AM
  #2  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,501
Total Cats: 4,080
Default

increase you MAPdot threshold to 80 kPa/sec.

Where are you running your map sensor line from?


also i think this issue was the boost cut set to 175kPa, it needs to be about 10kPa or so higher than what you spike to, cause the MS will cut fuel if it *thinks* you are goign to hit 175kPa, and I see you're spiking hard to 178kPa right before you junk goes whack.

Why does your boost control suck so bad, where is your wastegate getting its boost source? are you using a MBC.
Braineack is offline  
Old 03-11-2013, 08:50 AM
  #3  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default

When you say "MAPdot threshold to 80 kPa/sec", are you referring to "Cut Decel Setpoint:(kPa)"? See attachment.

I believe MAP sensor is connected to one of the fittings on top of the manifold. It's been a year since I've thought about that.
Attached Thumbnails AFR spike during acceleration-accel_decel_capture.png  
travisb is offline  
Old 03-11-2013, 08:57 AM
  #4  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,501
Total Cats: 4,080
Default

accel wizard.

you should tee off the FPR line and not use any nipples off the TB.
Braineack is offline  
Old 03-11-2013, 09:10 AM
  #5  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default

Ok. I changed MAPdot threshold to 80 and over boost to 185.

The waste gate signal line is also on a TB nipple. I just got the parts to move it to the IC pipe last week.

MAP should be on FPR line? Fuel Pressure Regulator?

Thanks
travisb is offline  
Old 03-11-2013, 09:16 AM
  #6  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default

Originally Posted by travisb
MAP should be on FPR line? Fuel Pressure Regulator?
I looked at some pictures and I think I have already done that. I'll have to double check.
travisb is offline  
Old 03-12-2013, 08:54 AM
  #7  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default

Regarding the FPR connection, I'm not sure I have one. At least not like in the BEGi documentation. Perhaps the previous owner did not install it or installed it differently.

See the attached pictures. I've highlighted different vacuum lines around the intake manifold.

The red line is the waste gate signal line that I plan on moving to the IC pipe post IC.

The yellow goes to some valve connected to the igniter and the canister.

I'm not sure where the blue, green, and pink go.

Can someone tell me where the lines go or what they do? Please be nice.
Attached Thumbnails AFR spike during acceleration-c360_2013-03-11-16-55-02-copy.jpg   AFR spike during acceleration-c360_2013-03-11-16-54-44-copy.jpg   AFR spike during acceleration-c360_2013-03-11-16-55-13-copy.jpg  
travisb is offline  
Old 03-12-2013, 08:57 AM
  #8  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,501
Total Cats: 4,080
Default

Blue is the FPR line, and Pink is the MAP sensor line tee'd off of Blue back to your MS.


did increasing the boost cut limit fix the issue?
Braineack is offline  
Old 03-12-2013, 09:09 AM
  #9  
Junior Member
Thread Starter
 
travisb's Avatar
 
Join Date: Sep 2011
Location: Chesterfield, VA
Posts: 252
Total Cats: 2
Default

I think it might have fixed it. I only got one brief attempt yesterday. So I'll try again when the weather is better.
Thanks!
travisb is offline  
Old 03-12-2013, 11:16 AM
  #10  
Supporting Vendor
 
DIYAutoTune's Avatar
 
Join Date: Feb 2013
Posts: 63
Total Cats: 7
Default

Keep us updated on if the issue where to arise again.
__________________
Peter - DIYAutoTune Tech Support
DIYAutoTune.com
We manufacture the most affordable high end engine management available anywhere, and we do it right here in the USA!

MegaSquirtPNP Gen2- 1 hour install Plug-N-Play for Miata's
-
MegaSquirt-3 Pro EMS - Top of the line ECU at an affordable price.
DIYAutoTune is offline  
Old 03-12-2013, 11:33 AM
  #11  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 375
Default

No EAE, no care.
hustler is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
satisfied
MEGAsquirt
144
11-05-2018 04:05 PM
itsMikey
MSPNP
3
09-28-2015 06:40 AM
elior77
MEGAsquirt
30
09-23-2015 06:38 PM
compuw22c
MEGAsquirt
4
09-12-2015 07:42 PM
Motorsport-Electronics
ECUs and Tuning
0
09-05-2015 08:02 AM



Quick Reply: AFR spike during acceleration



All times are GMT -4. The time now is 05:17 PM.