CEL 8 - MAF - Any Solution for this? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 07-25-2011, 11:06 AM   #1
Senior Member
Thread Starter
iTrader: (10)
 
Join Date: Apr 2007
Location: Ohio
Posts: 800
Total Cats: 3
Default CEL 8 - MAF - Any Solution for this?

So I was getting a CEL when I first installed the MS. It was for EGR. Traced this to a bent pin that wasn't making contact. Solved, right? No, still get the CEL. Hooked up the jumper to check codes and there is no more EGR code (#28) but now I have a #8 for the MAF.

Car is OBD1, 95.5. Anybody else have this issue? Solutions?
soloracer is offline   Reply With Quote
Old 07-25-2011, 11:37 AM   #2
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,775
Total Cats: 1,106
Default

Are you running the MS in parallel or stand alone? Is your MAF hooked up?
shuiend is offline   Reply With Quote
Old 07-25-2011, 11:57 AM   #3
Senior Member
Thread Starter
iTrader: (10)
 
Join Date: Apr 2007
Location: Ohio
Posts: 800
Total Cats: 3
Default

Parallel, no MAF.
soloracer is offline   Reply With Quote
Old 07-25-2011, 11:59 AM   #4
Senior Member
iTrader: (4)
 
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,367
Total Cats: 16
Default

The stock ECU still controls the CEL and will throw a code if it doesn't see a good signal from the MAF.

I'm getting a wicked case of deja vu, like I've already answered this question once this month. Oh yeah: https://www.miataturbo.net/showpost....9&postcount=17

Even if you wired the IAT straight to the MS, I think it's now paralleling that wire between MS and the stock ECU which I'm pretty sure is going to screw up the values that the stock ECU expects to see from a MAF. Not exactly sure of the basis for it and it's been a long time since I've looked at MS1 stuff, but the solution(s) are the same.
1. In your parallel boomslang/adapter harness, cut the wire to the CEL so the stock ECU can't trigger it.
2. Jumper the two pins in the glovebox connector per the instructions in FM's Link tuning manual pdf, so the light will come on only at ignition then go off when the motor is running, so you don't arouse the suspicion of state inspectors.

IMO the CEL doesn't give a whole lot of useful info when it works anyway. I don't miss it.
ScottFW is offline   Reply With Quote
Old 07-25-2011, 01:12 PM   #5
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,315
Total Cats: 1,913
Default

Quote:
Originally Posted by ScottFW View Post
Even if you wired the IAT straight to the MS, I think it's now paralleling that wire between MS and the stock ECU which I'm pretty sure is going to screw up the values that the stock ECU expects to see from a MAF.
I don't see how the IAT sensor is relevant to a MAF CEL. Yes, I understand that the IAT sensor is physically located inside the MAF housing on 1.8 NAs, however MAF and IAT are still separate signal lines.

Regardless of what he's done with the IAT sensor and its signal line, if he has no MAF sensor (and is not externally simulating a MAF signal) then the stock ECU is going to throw a code about it.

An extremely simplistic fix might be to parallel the TPS signal into the MAF input. I honestly have no idea whether this would work or not, it's just the only thing I can think of at the moment that would feed something vaguely resembling a MAF signal into the stock ECU in the absence of an actual MAF sensor and without having to build an external circuit to do the job. The lack of general-purpose analog outputs is one thing that I do miss on the MS as compared to the old EMU.


soloracer, do you actually need a working CEL? I thought Ohio had gotten rid of the smog check system?
Joe Perez is online now   Reply With Quote
Old 07-25-2011, 01:51 PM   #6
Senior Member
iTrader: (4)
 
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,367
Total Cats: 16
Default

Quote:
Originally Posted by Joe Perez View Post
soloracer, do you actually need a working CEL?
What I'm sayin. Cut it, but do the mod so it comes on briefly when the key is turned just in case an inspector cares. It takes 5 minutes.

BTW, these are the fault codes a properly functioning CEL can give on a 94-95:

01 IGF signal
03 SGT signal
04 SGC signal
08 Mass Airflow sensor
09 Engine coolant temperature sensor
10 Intake air temperature sensor (mass airflow sensor)
12 Throttle position sensor
14 Barometric absolute pressure sensor
15 Heated oxygen sensor (inactivation)
16 EGR function sensor
17 Heated oxygen sensor (inversion)
25 PRC solenoid valve
26 Purge solenoid valve
28 EGR solenoid valve (vacuum)
29 EGR solenoid valve (vent)
34 ISC valve

Take away the functions controlled or monitored in a more easily visible fashion by MS and a WBO2 and what are you left with? EGR (which will still work on a parallel install)? A few non-critical solenoids? Nothing of any great importance, certainly nothing about which I feel deprived of critical info due to modifying the CEL.
ScottFW is offline   Reply With Quote
Old 07-25-2011, 01:56 PM   #7
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,315
Total Cats: 1,913
Default

Quote:
Originally Posted by ScottFW View Post
What I'm sayin. Cut it, but do the mod so it comes on briefly when the key is turned just in case an inspector cares. It takes 5 minutes.
Well, yeah. And to elaborate, since he lives in Ohio, I don't even think that he needs to do the mod to light up the CEL at key-on, as I'm pretty sure that they did away with the inspection process altogether a few years ago.


Quote:
EGR (which will still work on a parallel install)?
Not without a MAF signal.
Joe Perez is online now   Reply With Quote
Old 07-25-2011, 02:53 PM   #8
Senior Member
Thread Starter
iTrader: (10)
 
Join Date: Apr 2007
Location: Ohio
Posts: 800
Total Cats: 3
Default

Quote:
Originally Posted by Joe Perez View Post
Well, yeah. And to elaborate, since he lives in Ohio, I don't even think that he needs to do the mod to light up the CEL at key-on, as I'm pretty sure that they did away with the inspection process altogether a few years ago.
Yeah, I don't need it here and don't really care if it functions. I just keep throwing around leaving this crappy state and don't want to do something short-sighted that might affect my ability to register the car elsewhere. Austin, TX. is my #1 choice for relo right now and they DO inspect. I think a few counties here still do it. I know they did in southern Ohio until a couple years ago; but not in central, where I live.
I'm thinking the key-on mod might be the way to go. Though the nerd in me wants to test Joe's TPS trick - just to see. Unfortunately I have too much on my "to-do list" (like tune this car and repair 3 motorcycles), so I'll probably take the easy way out.

Quote:
Originally Posted by Joe Perez View Post
Not without a MAF signal.
Seriously? So the EGR system that I left in place is worthless without that signal? Depressing. The engine bay could be a lot cleaner without that and the charcoal canister.

Thanks for all the help.
soloracer is offline   Reply With Quote
Old 07-25-2011, 02:55 PM   #9
Senior Member
Thread Starter
iTrader: (10)
 
Join Date: Apr 2007
Location: Ohio
Posts: 800
Total Cats: 3
Default

Quote:
Originally Posted by ScottFW View Post
The stock ECU still controls the CEL and will throw a code if it doesn't see a good signal from the MAF.

I'm getting a wicked case of deja vu, like I've already answered this question once this month. Oh yeah: https://www.miataturbo.net/showpost....9&postcount=17
Heh...oops. Missed that.

Is this true for all the 1.8 cars? I thought I remembered reading (way back in '07-'08) that it wasn't a problem for some folks.
soloracer is offline   Reply With Quote
Old 07-25-2011, 03:29 PM   #10
Senior Member
iTrader: (4)
 
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,367
Total Cats: 16
Default

Quote:
Originally Posted by soloracer View Post
Is this true for all the 1.8 cars? I thought I remembered reading (way back in '07-'08) that it wasn't a problem for some folks.
Should be true for all 94-95 (OBDI) parallel installs. The people who didn't have the problem most likely had standalone installs (no stock ECU to trigger the CEL). Later 1.8s were OBDII and have a different set of issues with which I am, thankfully, not familiar.
ScottFW 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
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM
Got bad Crank Angle Sensor and Random Misfire codes, but runs fine. Greasyman General Miata Chat 2 09-28-2015 11:44 AM
Now shipping NC MX-5 (2006-15) Precision Sliding Seat Mounts FAB Fab9 Tuning - Miata Performance Parts 0 09-11-2015 01:02 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 09:43 AM.