Stuttering: runs lean and plugs are white. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Prefabbed Turbo Kits A place to discuss prefabricated turbo kits on the market
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools
Old 03-28-2009, 01:51 AM   #1
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default Stuttering: runs lean and plugs are white.

Ok cross posting this problem again with m.net because i am not getting much traffic there.

Here is the problem:
The car first started to stutter once in a while when idling or when cruising. Today it would barely idle. It sounds like its running on few that 4 cylinders. I have i wideband and as soon as its starts stuttering the wb goes to 20afr.

When i press on the gas the car barely accelerates and sounds like a motorcycle. I got home and shut the car down. I could here the exhaust crackling, so knew it was hot as well.

I pulled the plugs and the cyclinder number one plug was almost white at the tip same for the number 3 but the rest were ok. I started the car back up and when i moved the plug that connects to the coil the car stuttered just like when i was driving and made the same noise. i moved the plug around and more i moved it more it did it.

Does it look like my coil is shot? is there a way to check?

I logged the car with megatune and everything except afr looks fine?

If the coil is bad why afr would go so lean like that?

I really need some input.

I am including a log that i took when the car was stuttering.

So i was wondering if it was a coil wouldn't the car run rich because the fuel would not get ignited? So its more likely its the fuel pump or injectors?
Attached Files
File Type: xls datalog200903271641ytyhjgjhg.xls (157.2 KB, 5 views)
Rushin is offline   Reply With Quote
Old 03-28-2009, 01:56 AM   #2
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

looking at the log it looks like when the car starts to stutter the fuel pressure goes all the way to 64 so something is got to be going on with the fuel.
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:03 AM   #3
Senior Member
iTrader: (8)
 
turbobluemiata's Avatar
 
Join Date: Aug 2006
Location: Springfield, IL
Posts: 1,019
Total Cats: 0
Default

I don't believe your MS reads fuel pressure....
turbobluemiata is offline   Reply With Quote
Old 03-28-2009, 02:06 AM   #4
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

Quote:
Originally Posted by turbobluemiata View Post
I don't believe your MS reads fuel pressure....
well i am not sure how accurate it is but its got a tab that says fuel pressure.
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:08 AM   #5
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

there is no sensor for that so disregard those values
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:09 AM   #6
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

also afrs look like they go rich, not lean
edit: which could indicate a bad coil if you've got 2 wet plugs and 2 white plugs and 9:1's afrs
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:12 AM   #7
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

20 is lean not rich if i am not completely wrong here.
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:16 AM   #8
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

so what could be going on here?
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:16 AM   #9
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

Quote:
Originally Posted by Rushin View Post
20 is lean not rich if i am not completely wrong here.
where are you seeing 20:1. at the end of his log he has a long period of very rich idle <10:1
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:22 AM   #10
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

when i look at it through excel i cant even find afr! But when i look at it it through megalog viewer i can see that i am in boost at like 3k rpm with afrs at 19 and 20. Thats when the car sounded really bad and i was going up a little hill.
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:24 AM   #11
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

i think the end of the log is when i unplugged the sensor to see if it was not running right. Thats why its like that.

And whats weird is that when afr says 21 the fuel pressure is maxed at 64 and then when afr goes back to normal and the car stops to stutter and goes back to 14.5 or so the pressure is down to 34-40 or so.

Can we safely say that this is most likely a fuel issue not spark? I just want to eliminate the spark and go right to the fuel?
Maybe first step would be to change fuel filter( even though i changed it like 5k ago) and run seafoam and if that does not help replace injectors and the pump?
I bought a set of 550cc injectors that will need to be cleaned anyway.
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:36 AM   #12
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

Quote:
Originally Posted by Rushin View Post
when i look at it through excel i cant even find afr! But when i look at it it through megalog viewer i can see that i am in boost at like 3k rpm with afrs at 19 and 20. Thats when the car sounded really bad and i was going up a little hill.
in mlv, where exactly (seconds) do you see this. i don't see it, though i am drunk
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:37 AM   #13
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

i have a fuel gauge that i can stick in between the fuel lines, that should help me see if there is a problem right? I am not sure what i would be looking for. What is the normal idle fuel pressure? what should it be under acceleration?
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:39 AM   #14
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

Quote:
Originally Posted by Mach929 View Post
in mlv, where exactly (seconds) do you see this. i don't see it, though i am drunk
Stay with me man, i need help here :-)

The best example is at 1222.036 and goes to 1224.618. the rpm is growing and the afr stays at 21

same is at 1240.815 to 1241
Rushin is offline   Reply With Quote
Old 03-28-2009, 02:42 AM   #15
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

dude ms can't log fuel pressure if you don't have a fuel pressure sensor supplying your computer with information. so those fp values are meaningless.
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:46 AM   #16
Elite Member
iTrader: (3)
 
Mach929's Avatar
 
Join Date: Oct 2004
Location: lansdale PA
Posts: 2,500
Total Cats: 0
Default

Quote:
Originally Posted by Rushin View Post
Stay with me man, i need help here :-)

The best example is at 1222.036 and goes to 1224.618. the rpm is growing and the afr stays at 21

same is at 1240.815 to 1241
you are lean in those areas but you're not even in boost. try working on your acceleration wizard
Mach929 is offline   Reply With Quote
Old 03-28-2009, 02:51 AM   #17
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

ok disregarding the fuel pressure and all, what could be cause this stuttering and afr going all the way to lean? I mean i was in the car and right when the car started to stutter i looked at my wideband gauge and in the ms and it was at 21. right when the car stopped stuttering the afr was back to normal. And i should say that the rpm gauge bounces like crazy from what ever rpm i am in to zero when this is happening.
Rushin is offline   Reply With Quote
Old 03-28-2009, 03:03 AM   #18
Senior Member
iTrader: (8)
 
turbobluemiata's Avatar
 
Join Date: Aug 2006
Location: Springfield, IL
Posts: 1,019
Total Cats: 0
Default

bad coil or igniter IMO
turbobluemiata is offline   Reply With Quote
Old 03-28-2009, 03:07 AM   #19
Senior Member
Thread Starter
iTrader: (3)
 
Join Date: Jul 2008
Location: Minneapolis, MN
Posts: 963
Total Cats: -1
Default

Quote:
Originally Posted by turbobluemiata View Post
bad coil or igniter IMO
that was what i was thing. how would i check for that? where is the ignitor btw? i will take a video of the car tomorrow and post it here.
Rushin is offline   Reply With Quote
Old 03-28-2009, 03:39 AM   #20
Senior Member
iTrader: (8)
 
turbobluemiata's Avatar
 
Join Date: Aug 2006
Location: Springfield, IL
Posts: 1,019
Total Cats: 0
Default

passenger side by fuse box
turbobluemiata 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
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
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
01-05 Fab9 PNP COPs (used) FrankB Miata parts for sale/trade 6 09-30-2015 12:48 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 04:32 AM.