Fuel cut? Knock? WTF is this? - 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 06-03-2011, 01:34 AM   #1
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Location: Saint Paul, MN
Posts: 1,298
Total Cats: 22
Default Fuel cut? Knock? WTF is this?

Hey guys, I just had a shop dynotune my car and AFAIK my car ran great on the dyno, and on the way home it ran fine too, however after taking it out I decided to run a few logs and see how my coolant was looking since we pulled another 60hp and 40tq out of thin air.

Take a look at the log (02 is far more apparent and cleaner of a log), I build boost to 14psi (sometimes less, like 5-7psi...), and for no apparent reason I have a lurch like I take my foot off the throttle, or slam on the breaks, then like 1/2 second later it builds boost back to 14psi.. From what I can see on the log, I don't have any apparent knock spikes that would cause fuel cut, and I don't have any timing change to show knock either.. What the hell is it?
Attached Files
File Type: zip miata stuff.zip (231.2 KB, 72 views)
Der_Idiot is offline   Reply With Quote
Old 06-03-2011, 01:46 AM   #2
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Location: Saint Paul, MN
Posts: 1,298
Total Cats: 22
Default

Sorry, I'll clarify a bit. I lost the timestamp when I converted to CSV, but..

Cells 677-680 have it, 690, 695, 848, 861, 869..

Now, a thought. Could this be boost surge and I just can't hear it? I'm not sure a Dynojet puts enough load on an engine to produce road-type loads, but hell I have no idea at this point....
Der_Idiot is offline   Reply With Quote
Old 06-03-2011, 03:14 AM   #3
Senior Member
iTrader: (2)
 
Join Date: Aug 2005
Location: Granbury, TX
Posts: 567
Total Cats: 1
Default

I can't look at your log on this computer, but from your description..

What is your ignition setup like? Stock? what plugs/gap?

What's your overboost setting at?

Do you have noisy readings in your log? If so, what do your ECU and main grounds look like?

Last edited by greenday3437; 06-03-2011 at 03:24 AM.
greenday3437 is offline   Reply With Quote
Old 06-03-2011, 04:21 AM   #4
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Location: Saint Paul, MN
Posts: 1,298
Total Cats: 22
Default

Toyota COPs, NGK Resistor-less plugs running .04 gap

Maximum boost is set to 22.5psi, boost target is set to 18.0

Noisy readings? Please elaborate.

Edit: Some data from my log for easier viewing:

Code:
timestamp	 coolant temp (F)	 engine speed (rpm)	 vehicle speed (mph)	 tps (%)	 air temp (F)	 duty cycle (%)	 boost (psi)	 knock ramp (V)	 AFR/LMBD (ratio)	 advance (deg.)	 vacuum (mmHg)	 load (%)
59216	197.6	3800	77	102	80.6	32.8	14.12	0.02	11.61	4	0	109.44
59288	197.6	3750	78	102	80.6	31.6	13.51	0.04	11.61	3.5	0	109.44
59360	197.6	3750	78	102	80.6	31.6	13.51	0.06	11.47	4.5	0	108.87
59432	197.6	3850	78	102	80.6	31.2	12.89	0.04	11.47	4.5	0	108.87
59504	197.6	3800	79	102	80.6	31.2	13.51	0.06	11.61	4.5	0	108.87
59576	197.6	3700	78	102	80.6	26	7.37	0.06	11.61	5.5	0	106.02
59648	197.6	3950	77	102	80.6	27.2	7.37	0.04	10.88	7.5	0	104.88
59720	197.6	3950	80	102	80.6	28	7.98	0.04	11.03	7.5	0	107.73
59792	197.6	3900	82	102	80.6	28.4	9.82	0.06	11.32	8	0	107.16
59864	197.6	3850	81	102	80.6	30	10.44	0.04	11.47	8	0	107.16
59936	197.6	3900	80	102	80.6	29.6	11.05	0.04	11.76	6.5	0	107.73
60000	197.6	3900	83	102	80.6	31.2	11.05	0.06	11.76	6.5	0	108.3
60072	197.6	3900	82	102	80.6	32	12.28	0.02	11.76	6	0	108.87
60144	197.6	3950	80	102	80.6	32.4	12.89	0.04	11.76	5.5	0	108.87
14.12psi
13.50psi
13.50psi
12.89psi
13.51psi
7.37psi
7.37psi
7.98psi
9.82psi

The (mostly minor) fluctuations like 14.12 to 13.50 are from some WG flutter that I'm working on fixing. A drop from 13.5 to 7.37 is the lurch I am talking about. Knock threshold is .30 across the board, I could lower it to be .21 but that's cutting it very close to what the engine normally makes for noise.

Last edited by Der_Idiot; 06-03-2011 at 08:04 AM.
Der_Idiot is offline   Reply With Quote
Old 06-03-2011, 09:27 AM   #5
Newb
 
Join Date: Oct 2007
Location: In the Cloud
Posts: 15
Total Cats: 1
Default

Luke has the same thing happening on his MR2, except accompanied with the drops in boost is heavy afterfiring and black smoke. Did you hear anything from the engine when the boost dropped?

To answer your question no, it's not surge. You'd have to hit your overboost value for it to cut spark/fuel, and in the logs you don't see surges. Besides, I thought you brought it as high as 18psi before? Jordan didn't set your "max" boost as if it was the TARGET boost, did he? If that's the case and you're tuned for like... 14.5 psi, you might have a small issue.
asellus is offline   Reply With Quote
Old 06-03-2011, 09:35 AM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

could it be youre only running ~4 of spark advance at 14psi?
Braineack is offline   Reply With Quote
Old 06-03-2011, 09:42 AM   #7
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,658
Total Cats: 39
Default

Ugh good spot Brain.

Your EGT's must be insane with such retarded ignition timing.
richyvrlimited is offline   Reply With Quote
Old 06-03-2011, 09:43 AM   #8
I'm Miserable!
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,869
Total Cats: 3
Default

is is straight off the wastegate or do you have a boost controller tied in?
Techsalvager is offline   Reply With Quote
Old 06-03-2011, 09:52 AM   #9
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

lol @ paying money for this "tune". Do yourself a favor by learning how to tune spark, then do it all yourself. General "give a ****" will get you more success than this.
hustler is offline   Reply With Quote
Old 06-03-2011, 10:02 AM   #10
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

Quote:
Originally Posted by richyvrlimited View Post
Ugh good spot Brain.

Your EGT's must be insane with such retarded ignition timing.

I retard my timing to 10 in boost for my soft cut limiter
Braineack is offline   Reply With Quote
Old 06-03-2011, 11:19 AM   #11
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,658
Total Cats: 39
Default

Quote:
Originally Posted by Braineack View Post
I retard my timing to 10 in boost for my soft cut limiter
Ditto, plus mine hit 10deg on a trackday due to elevated intake temps. Must get my WI installed...

Still 6deg more than 4 which is a whole lotta timing
richyvrlimited is offline   Reply With Quote
Old 06-03-2011, 11:59 AM   #12
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

A few things.

Log more stuff. I attached a log template to this post that you can use. Everything in that template is useful information. To use it, open up the hydra datalogger and go to file/load profile. After you arrange it to your liking, go to file/save profile as default.

When you do dyno tuning, I recommend doing a log for each individual pull once you get in the ballpark for fuel/timing. Look at the log after each pull and see the "state of the union".

Your timing map is... amazingly, more conservative than FM's Hydra base map. Unless you are running 87 octane I don't see a reason for it to be this conservative.

Regarding your timing: You are exceeding the knock threshold and pulling timing. This would be clear if you were logging "knock retard". Your knock threshold is .32V which is too low. Your "excessive knock" setting is .5v which means you might be entering limp mode too. Unfortunately, I can't see all the other sensor readouts which would affect timing trim because they're not in the log.

If you have an ECU controlled alternator, those lurches could be from your alternator control PWM MAP 2 being improperly setup. That bitch typically has a curve or ramp, not a plateau. Hydra will freak out and lurch if you go over voltage. If you log "batt voltage" you will be able to see. The lurches are not surge. Wild guess but what BOV are you using?

If you have VVT it's not being used?

Your ignition trigger and sync type looks incorrect. That might be bad. You may want to send your map to Jeremy and ask him to look over the settings. Even if he would charge you, it might save you a lot of aggravation.
Attached Files
File Type: zip hydralogtemplate.zip (163 Bytes, 53 views)

Last edited by Faeflora; 06-03-2011 at 02:00 PM.
Faeflora is offline   Reply With Quote
Old 06-03-2011, 12:05 PM   #13
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Also, if there were other logs you didn't upload and that timing map is really truly MBT minus a few degrees for you, then your mechanical timing is off.

To check that with the hydra, save your map then set your idle timing cells to 10. Then zero out the CTS and ATS ignition trims. Look at "ADV" in the real time readout. It should say 10. If it's not, something else is affecting your timing, possibly 2D Idle Speed Control/ISC Ignition trim. Zero that out. When your real time readout says 10, hook up your timing light and flash the wheel.
Faeflora is offline   Reply With Quote
Old 06-03-2011, 02:00 PM   #14
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

I some good timing maps I can share with you btw..
Faeflora is offline   Reply With Quote
Old 06-03-2011, 02:02 PM   #15
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

I bet with that spark retard and that boost coupled with stock coils, you're getting spark blowout.
Braineack is offline   Reply With Quote
Old 06-03-2011, 02:04 PM   #16
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by Braineack View Post
I bet with that spark retard and that boost coupled with stock coils, you're getting spark blowout.
Wouldn't that be indicated by AFRs going to **** either rich or lean?
Faeflora is offline   Reply With Quote
Old 06-03-2011, 02:12 PM   #17
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

it does go rich...
Braineack is offline   Reply With Quote
Old 06-03-2011, 05:29 PM   #18
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Location: Saint Paul, MN
Posts: 1,298
Total Cats: 22
Default

I stayed up all night pissed off and woke up at 2pm, I'm now ready to figure this bitch out.

Asellus: No sounds, just felt like the engine cut out and lit back up 1/2 second later. I did bring it that high before, but the turbo apparently was surging or something, not sure as I wasn't allowed to be close enough to hear it...

Fae: I'll add those to my logging. As for your timing, aren't you running WI, wouldn't that throw it off? Or do you have a tune from before the WI? I really wasn't in the booth during tuning as they keep everyone out and around a wall (with a window) for safety or whatever. I remember the first thing he did was pull timing, without even doing an initial pull to verify. I would have loved to be in there though. He tuned around 12:1 afr goal, I would have preferred to keep it around 11.5~ roughly for safety margin. My alternator is not ECU controlled, it came off a 97. The BOV is one that came with my FM2, some company called "Fast Bits", not sure if I can adjust it as I don't have any directions in the box it came in. Head is a 99, no VVT though it has a VICS intake (tuned already). Ignition trigger and sync?

I will triple-check my timing, thanks for that bit there. I recently had to change the base timing in the hydra as it was about 2* off, I'll try zeroing out those fields.


Brain: I'm going to log knock events, I have a feeling it's pulling timing resulting in low advance. I'm running Toyota COPs with NGK resistorless plugs gapped to .04, it was working fine but with the retard, I'll gap them smaller after I check a new map.

Tech: Turbo streight to an adjustable WG.
Der_Idiot is offline   Reply With Quote
Old 06-03-2011, 05:49 PM   #19
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

you need more than 10* advance at that boost, you're logging 4.
Braineack is offline   Reply With Quote
Old 06-03-2011, 06:23 PM   #20
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default



I am not running WI. This is what you need to do:

1. Check your base timing
2. Check your trigger and sync. First page in Settings 1. I think yours is wrong.
3. Log a big fat 4th gear pull to redline with that template I sent you.
4. Upload it here
5. Do not boost more

The real potential issue here is your timing, then your boost hiccup.
Faeflora 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 59 12-15-2017 09:00 PM
Walbro 255lph Fuel Pump $50 lsc224 Miata parts for sale/trade 2 10-01-2015 10:17 AM
"Chimney Ethanol" E100 MiataGarage Engine Performance 5 09-30-2015 12:04 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 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 01:20 AM.