Before I throw parts at it - help diagnose lean under load - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


ECUs and Tuning Discuss Engine Management, Tuning, & Programming

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 11-13-2013, 11:03 AM   #1
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default Before I throw parts at it - help diagnose lean under load

I am having a problem where at about 4800-5500 rpm I am going lean under boost.

Attached are two maps, one from last night and one from this morning.

Important details:
2001 with Megasquirt 3x
460cc injectors never tested
DW200 fuel pump.
Knock sensor works, but I am not sure if it's calibrated correctly
Running Precision 4828 turbo with EBC.
Stock original coils, stock original wires with 90k miles on them (unless they were replaced before I bought the car at 44k miles)
NGK plugs (7 temp) gapped to .029-.031

Run 10-12 info:
Max boost on EBC map was 162kpa I think. I have previously had the map as high as 178kpa at 100% throttle.

Run 10-13 info:
Max boost is listed as 150kpa across the board. I notice that actual boost sticks to 160'ish so I imagine that is my waste gate pressure.

I was running VEAL on both runs so looking at the tune file might not tell you everything but I will include it either way.

Looking at the log, what do you see?



Attached Thumbnails
Before I throw parts at it - help diagnose lean under load-11-12.jpg   Before I throw parts at it - help diagnose lean under load-11-13.jpg  
Attached Files
File Type: msl 2013-11-12_17.46.13.msl (58.1 KB, 46 views)
File Type: msl 2013-11-13_06.50.50.msl (47.9 KB, 47 views)
File Type: msq CurrentTune.msq (172.8 KB, 35 views)

Last edited by Chiburbian; 11-13-2013 at 12:49 PM.
Chiburbian is offline   Reply With Quote
Old 11-13-2013, 11:49 AM   #2
Elite Member
iTrader: (6)
 
blaen99's Avatar
 
Join Date: Sep 2010
Location: Seattle, WA
Posts: 4,112
Total Cats: 27
Default

Are you certain you haven't maxed out your injectors?
blaen99 is offline   Reply With Quote
Old 11-13-2013, 12:29 PM   #3
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Quote:
Originally Posted by blaen99 View Post
Are you certain you haven't maxed out your injectors?
I highly doubt it. Log says my duty cycle is between 66 and 80% depending on the pull. Plus, I ran the pull through virtual dyno and my max HP is showing only 180 or so. I recall most people consider 460s being good for 250hp...

The fact that I never had the injectors tested though gives me pause.

I will pull my plugs after my drive home and see if they are wet or have any discoloration.
Chiburbian is offline   Reply With Quote
Old 11-13-2013, 12:45 PM   #4
Senior Member
iTrader: (4)
 
Join Date: Jul 2006
Location: Shelton, CT
Posts: 672
Total Cats: 2
Default

Yes 460s should be good for 250hp at least. Injector service is a relatively cheap safety measure.
Harv is offline   Reply With Quote
Old 11-13-2013, 01:03 PM   #5
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Based on what you see here, how likely is it that it is a fuel issue? How about a spark issue?

I can't imagine having "spark blow out" with only 8psi or so, but at the same time they are old wires. I just don't like the idea of spending money on something I will be replacing next year when I upgrade to LS coils. I don't have the money to do it now.
Chiburbian is offline   Reply With Quote
Old 11-13-2013, 01:04 PM   #6
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,008
Total Cats: 583
Default

I don't think your wideband is reliable. In the first pull, there's no way your engine will be making power at 18.5:1 AFR (unless you were totally running like doo up there).
hornetball is offline   Reply With Quote
Old 11-13-2013, 01:14 PM   #7
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

See, that makes sense! Could it be that I am soaking the wideband? Is that a thing? Reason I ask is I see my AFRs are way below my target during my pull. Now I DID fatten it up in case I was actually going lean so VEAL is gradually bringing it back to target but it could be that I am injecting so much fuel that I am causing a problem with the wideband.

Anyone know if this is a possibility?

Just so you know, it FEELS like it is not making enough power right before it goes lean.

EDIT: F'it. NGK plug wires are only about $30 and so I will replace them. I also leaned out my map a bit in the 160% area leading up to 5000rpm.
Chiburbian is offline   Reply With Quote
Old 11-13-2013, 01:31 PM   #8
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,790
Total Cats: 128
Default

What's your overboost set at? If it's close to what you're running you may want to bump it up a little. I can't remember what it looks like on a datalog, but I've run into that a few times and it's one of those stupid little things that's easy to overlook.

As far as spark blowout, you can narrow the plug gap to ~.020 and see if that helps at all. My '99 was dying out like that until I narrowed the gap and it went away. I added COPs a few weeks later and was able to return the gap to .040 without issues.
pdexta is offline   Reply With Quote
Old 11-13-2013, 01:40 PM   #9
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,008
Total Cats: 583
Default

You might be overheating the wideband. It's known to happen. Where is it located? Preferred location would be just before the cat.

At 18.5:1 under load, I would expect tons of det + misfiring -- we're talking running REALLY badly. You would know and take your foot out of it quick.
hornetball is offline   Reply With Quote
Old 11-13-2013, 01:42 PM   #10
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,008
Total Cats: 583
Default

Based upon the jitter in the RPM line, I'd say spark blowout is a good possibility like Scott said. Once you start misfiring, your AFR will go way up due to unburned oxygen regardless of what you do with fuel.
hornetball is offline   Reply With Quote
Old 11-13-2013, 03:35 PM   #11
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Overboost is set to something stupid like 190... That isn't it. I have hit it before.

Quote:
Originally Posted by hornetball View Post
You might be overheating the wideband. It's known to happen. Where is it located? Preferred location would be just before the cat.

At 18.5:1 under load, I would expect tons of det + misfiring -- we're talking running REALLY badly. You would know and take your foot out of it quick.


I want to say that the oxygen sensor is right before the cat as is recommended. Overheating is a possibility. We will see.

Re: 18.5:1 - agreed. If I was truly going that lean I wouldn't expect my motor to be long for this earth.

I will pick up plug wires on the way home and change my gap to .025 when I get home. Hopefully that helps.
Chiburbian is offline   Reply With Quote
Old 11-15-2013, 10:44 AM   #12
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Re-gapped plugs to .025 and I am pulling to red line under full boost with no lean-out.

To me, .025 seems way too small of a spark gap but hey, it works. I feel like I really want to upgrade my ignition system next year but I am unsure of how much it will really affect performance.

Oh well, on to the next issue. Thanks for the help guys.
Chiburbian is offline   Reply With Quote
Old 12-10-2013, 07:32 PM   #13
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Or - not.

Still going lean in boost. (drats)

That is after plug wires. Coils haven't been replaced yet. I am holding off on replacing them due to that they are $90 for the pair (best case) and I'd rather sink my money into improvements rather than replacements. So, I bought a set of ID1000s.

I should have them on Thursday. Unfortunately, we are experiencing an early winter here in the Chicago area and I don't drive it in snow and salt. No traction anyhow.

If it warms up enough and the roads look clean I will take it out for a spin after injectors.
Chiburbian is offline   Reply With Quote
Old 12-12-2013, 09:58 PM   #14
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

I think I have a very promising lead.

When I was doing my initial build I checked the resistance of my injectors. I got readings that led me to believe they were high-z.

I bought ID1000s but they haven't arrived yet so I started to do the disassembly just to keep me busy. I checked the part numbers on the injectors (195500-1350) which come back to 460cc Peak and Hold style injectors. I broke out my multimeter and tested impedance. I got 95 ohms... Clearly wrong. I put the two leads against each other and got 95 ohms...

So I replaced the 9v battery (which read "best used before 2004"). I don't remember ever changing the battery. I bought the multimeter in 1997ish...

After inserting the leads a few times to wear off any corrosion I got the "zero" down to .3 ohms. Not perfect but enough to tell me what's going on.

My injectors read between 2.5 and 3 ohms.

I don't have resistors, I don't have the peak and hold box, and I never did anything consciously in my setup to accommodate them. (It is a MS3x)

So, is there anything I have to check that I might have screwed up electrically by running them improperly for months?

Thanks!

Last edited by Chiburbian; 12-13-2013 at 08:05 AM.
Chiburbian is offline   Reply With Quote
Old 12-17-2013, 10:05 PM   #15
Newb
 
Join Date: Dec 2013
Posts: 15
Total Cats: 0
Default

Pardon the noob intrusion, but I have a question about overboost. I thought it was when there is too much pressure buildup. By what it's set to, do you mean at what point you have fails safes set to go off at?
f1-mx-5 is offline   Reply With Quote
Old 12-18-2013, 09:35 AM   #16
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Yes. Megasquirt is set to cut fuel and spark at 190kpa as my target is 170kpa.
Chiburbian is offline   Reply With Quote
Old 12-18-2013, 02:14 PM   #17
Supporting Vendor
 
Matt Cramer's Avatar
 
Join Date: Sep 2006
Posts: 2,264
Total Cats: 51
Default

Those aren't low impedance injectors by any chance? If so, they may be overheating the drivers.
Matt Cramer is offline   Reply With Quote
Old 12-18-2013, 02:18 PM   #18
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Quote:
Originally Posted by Matt Cramer View Post
Those aren't low impedance injectors by any chance? If so, they may be overheating the drivers.
Yes, matter of fact they are. I just traded an email or two with you about this.

The good news is that now we have seen some new funky stuff that can happen when you use the wrong parts and maybe in the future someone can point to this thread and say "is THIS what your car is doing?"

Live and learn right?
Chiburbian is offline   Reply With Quote
Old 12-18-2013, 05:53 PM   #19
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 197
Default

Replace all the VND drivers used. I've had happen to a customer and he fried a VND on a 25psi pull (scary as he lost a cylinder and we thought the engine was toast)
Reverant is offline   Reply With Quote
Old 12-18-2013, 06:22 PM   #20
Elite Member
Thread Starter
 
Chiburbian's Avatar
 
Join Date: Feb 2008
Location: Gilberts, IL
Posts: 2,158
Total Cats: 131
Default

Just to be clear you are saying I should replace all the injector drivers that I used to drive my injectors? Even though they were working when I took the car down a week ago? (Are they now apt to fail in your opinion?)

Also, are they something I can replace myself or do I need to send my board in to be replaced/repaired?

Thanks.
Chiburbian 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
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 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
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 04:20 PM
why is my car running like pewp? (tune/datalog) itsMikey MSPNP 3 09-28-2015 07:40 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 08:37 PM.