I Threw Gasoline On The Fire And Now I Have Stumps For Arms And No Eyebrows - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 05-23-2011, 11:56 AM   #1
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default I Threw Gasoline On The Fire And Now I Have Stumps For Arms And No Eyebrows

but here's the latest issue I'm having...

This all started after my alternator failed, it did so in a way that allowed huge 17+ voltage spikes. My boost solenoid seems to have been vicitim of it, and my TPS signal has become very unstable as well, it was never perfect, but it's worse now.

I started noticing after I replaced the alt, my idle was getting unstable. I had just loaded new firmware that required retuning my PID code, but I was unable to tune out some oscillation. I reverted back to an older firmware with a known good map and the same thing occured.

Fooling around I found that if I idle rich, it's very smooth and pulls a lot of vacuum, notice the pulse width. This is with '01 240cc injectors, I pulled my 460s in an effort to maybe rulle them out. Same thing was happening on them.

Once I lean it up just a little, I go from a solid 33kPa to around 35kPa and the idle becomes slightly unstable, enough to notice a slight oscillation. I can only really tell becuase of the exhaust drone.

In the video I select my entire idle VE table and strat reducing fuel, the value is which it's fueling off of remains fairly steady. Any amounts of fine tuning the VE table are to no avail.

So as soon I bring it nearly 14.0:1 the vacuum starts going crazy between 33-38Kpa and I can't maintain a smooth idle no matter what I do, the only thing that solves it is runnig rich agian.

This didn't used to be the case with my car and I'm unable to figure out what the cause is. I cannot find any vacuum leaks, and the only other guess is the HG, but there's no real evidence of it.



Note: the crazy blip at 1:01 is my TPS enrichments causing havok, my TPS signal is very unclean.
Braineack is offline   Reply With Quote
Old 05-23-2011, 12:46 PM   #2
Elite Member
iTrader: (8)
 
Join Date: Aug 2007
Location: Bellingham, Wa
Posts: 2,732
Total Cats: 3
Default

My car has always idled poorly at anything over ~13.5 or so. I figured that was just the nature of the beast.
wayne_curr is offline   Reply With Quote
Old 05-23-2011, 12:50 PM   #3
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,775
Total Cats: 1,106
Default

Quote:
Originally Posted by wayne_curr View Post
My car has always idled poorly at anything over ~13.5 or so. I figured that was just the nature of the beast.
I have told Scott that a million times, it is not an acceptable answer for him.
shuiend is offline   Reply With Quote
Old 05-23-2011, 12:51 PM   #4
Elite Member
iTrader: (8)
 
Join Date: Aug 2007
Location: Bellingham, Wa
Posts: 2,732
Total Cats: 3
Default

Quote:
Originally Posted by shuiend View Post
I have told Scott that a million times, it is not an acceptable answer for him.
Lol I even remember reading some megasquirt documentation (cant remember which) that said your car will idle best at around 13.3afr! Pretty sure it was miata specific.
wayne_curr is offline   Reply With Quote
Old 05-23-2011, 01:01 PM   #5
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

I kinda hope that's the deal. I'm starting to just think that too. The only reason I don't is because I've been idling at 15:1 for the past few months without issues. And When I first went seq. fuel last March, I could even idle at like 16:1 if I wanted to, only then is where I'd start having this same issue. I've more or less idled at 14.5:1 for the last 4 years on MSI, MSII and MSIII. If it wasn't for that I wouldn't think there was a problem really.

Only thing is, I do notice my PWs are more or less the same as before. High 1.699, low 1.7XX, but the AFRs are now richer, so I'm wondering if my sensor was off. Last time I dynoed in Nov, my tune was crazy rich according to the dyno's wbo2 and the large amounts of black smoke, where I thought it was 12.0:1 in boost.

It could also make sense that in spots where I tuned for 16.0:1 it's very hesistent now, where it wasn't before, if it was always richer than indicated.

I had recalibrated my sensor, and I just went as far as swapping it out for my old spare one this weekend to double check the AFRs are correct, unless the LC-1 unit itself is failing.

I even went out and installed an adjustable FPR, dropped the pressure down to like 20psi at idle so I could increase the pulse widths to make sure it wasn't the injectors being driven too fast. then I swapped in the 240cc injectors to completely rule them out.

Only other thing I could thing is a vacuum leak or HG failure. I've pressure tested the cooling system, and it can hold 20psi over an extended perioud of time without loss. When idling at temp, there is no loss and no flickering of the needle when revving the motor. I do seem to have a slight loss of coolant over time according to the levels in my overflow over the last 4 weeks.

The only other thing I cant think is a small leak at the coolant ports on the IM flange and it's only leaking between that and a runner, allowing water to get into the motor, but no leaks anywhere else. But I'd think I'd see that on my coolant pressure test. All pistons when looking through the spark plug holes appear dirty and non-steam cleaned.

I've sprayed highly flammable brake cleaner all over the intake manifold trying to find a leak. all bolts are tight. It's hard to get up under and spray the bottom of the flange, but I'd expect to hear some suckage. Even if I get the must minute amount of cleaner in my BOV at idle, the engine stumbles, so im sure I would have found a leak by now.

TB is correct. Double checked it. Even made sure the piston was actually at TDC when indicated on my crank pulley.

So I'm either left with this is normal, you can't idle stoich, or I'm missing something else.
Braineack is offline   Reply With Quote
Old 05-23-2011, 01:54 PM   #6
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 198
Default

Shitty injectors tend to do that, get proper injectors. RX-7 injectors are shitty, period.

Having said that, post a datalog, I have another theory.
Reverant is online now   Reply With Quote
Old 05-23-2011, 02:15 PM   #7
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

Like I said, that video is running Y8s' '01 240cc injectors. Had the deadtime set to like 0.8, 40psi of fuel pressure.
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:01 PM   #8
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 198
Default

The stock injectors are not terribly good either. My car tends to whack out if I try to idle at 16:1. On the other hand, a customer's built 1.6 on 650cc EV14 injectors idles at 17-18:1 like it was born that way.
Reverant is online now   Reply With Quote
Old 05-23-2011, 03:06 PM   #9
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Quote:
Originally Posted by Braineack View Post
Like I said, that video is running Y8s' '01 240cc injectors. Had the deadtime set to like 0.8, 40psi of fuel pressure.
Probably not enough pressure to keep those injectors happy.
Ben is offline   Reply With Quote
Old 05-23-2011, 03:09 PM   #10
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

im just saying, same things happens on both injectors and I mistyped, it WAS 60psi.

Then I found the fpr I was using was very consisent when settling into an idle pressure so I removed it and I'm back on 460s now on the factory fpr.
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:09 PM   #11
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Quote:
Originally Posted by Reverant View Post
On the other hand, a customer's built 1.6 on 650cc EV14 injectors idles at 17-18:1 like it was born that way.
Word. I put some EV14 injectors on our test mule and the idle now ROCKS, even with MS1 batch fire. I've been bugging Jerry to stock these injectors...
Ben is offline   Reply With Quote
Old 05-23-2011, 03:12 PM   #12
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 198
Default

Brain, check C16, C17, C18 and C22. Replace if in doubt.
Reverant is online now   Reply With Quote
Old 05-23-2011, 03:12 PM   #13
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Quote:
Originally Posted by Braineack View Post
im just saying, same things happens on both injectors and I mistyped, it WAS 60psi.

Then I found the fpr I was using was very consisent when settling into an idle pressure so I removed it and I'm back on 460s now on the factory fpr.
Ok, 60 psi should do it.

Those who run S4 RX7 injectors aren't allowed to complain about idle quality.
But post a datalog so we can have a look-see.
Ben is offline   Reply With Quote
Old 05-23-2011, 03:14 PM   #14
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

I would buy EV14 660cc injectors if I knew that would solve the issue. That's why I tossed in y8s injectors to see how lean I could idle them. They reacted the exact same, as soon as I tried to brin git up past 14.0:1 or so, it gets very unstable. No matter the ign timing I lock it at or engine speed. So long as I keep the AFRs below 13.5:1 the vacuum increases and stays solid.


Reverant has my log, he can post it. I cant from here.
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:16 PM   #15
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

Quote:
Originally Posted by Reverant View Post
Brain, check C16, C17, C18 and C22. Replace if in doubt.

of course those are probaly the ones I had spares for that I tossed when cleaning out my inventory drawer. think they got hit on the power surges?
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:18 PM   #16
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 198
Default

Could happen. C16 is the most likely candidate.
Reverant is online now   Reply With Quote
Old 05-23-2011, 03:22 PM   #17
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

I understand they are on the 5v reg circuit, but what is the main purpose - Care to share your hypothesis?

I think I have two spare C16 and c17, easy enough to swap. If not I can pick them up.
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:25 PM   #18
Supporting Vendor
iTrader: (10)
 
Reverant's Avatar
 
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,440
Total Cats: 198
Default

C16 is your basic input filter and is needed for stability, I've seen weird things happening with it either missing (it happens to the best of us, which is why I check 35 different things on each ECU I build) or crapped out. C17 helps with transient response.
Reverant is online now   Reply With Quote
Old 05-23-2011, 03:31 PM   #19
Boost Czar
Thread Starter
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,840
Total Cats: 1,786
Default

yeah, reading over at msextra.com there is a correlation between voltage spikes and losing those. One guy said his ran but had missing issues. Kinda sounds like mine (it does miss every now and again at idle). I'll give it a check.
Braineack is offline   Reply With Quote
Old 05-23-2011, 03:41 PM   #20
Elite Member
iTrader: (1)
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 4,682
Total Cats: 216
Default

Ive experienced this while tuning other cars, Ive alwasy assumed it was due to difefernt brands of injectors.
Basically, some engines Ive gotten to idle way lean, like 15-16 AFR, rock solid, no lope, no missing. Then there are others that refuse to idle well with anything less than ~13:1

My buddy Tw34k who used to post on here occasionally had his civic running in the 16s at idle with RC 550cc injectors.
I think I have a video of it starting up and idling on my youtube account, Ill see if I can find it.

Also, ignition timing does play a roll, but the exact nature of the relationship is not clear to me still. It usually just requires trial and error to see what will allow you to lean it out.
Full_Tilt_Boogie is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
1994 Spec Miata Race Car SM/SM2/SSM For Sale Quinn Cars for sale/trade 6 10-23-2016 08:58 AM
No spark while cranking? navalhawkeye MEGAsquirt 9 10-07-2015 08:10 PM
Odd Steering issue interestedofold Suspension, Brakes, Drivetrain 5 09-29-2015 02:42 PM
ME221 Now has Autotune and Long Term Fuel Trim Tables Motorsport-Electronics ECUs and Tuning 0 09-05-2015 09:02 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 02:21 PM.