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-   -   Help me figure my idle and AFR problem. (https://www.miataturbo.net/general-miata-chat-9/help-me-figure-my-idle-afr-problem-18300/)

levnubhin 03-14-2008 09:59 AM

Help me figure my idle and AFR problem.
 
1. My Idle rpm and my idle AFP's are all over the place and my gas mileage sucks bad. Sometimes I idle rich, other times lean. Sometimes my idle is below 500 rpm, other times above 500 and sometimes above 1000.

2. When crusing and very light on the gas I run lean 15-16.0, if I give a slight amount of gas the I go rich between 11-10.0. When WOT its usually low 13's. When I decel in gear my afr's go off the chart lean. The check engine light came on this morning when at a light but went off once I started moving. Yesterday I replaced the O2 sensorwith a new one and the IAC with one a friend gave me, which means I have no idea if its any good. After changing both parts my condition seems to have worsened.

Setup Is T2854,1.8inj,begi AFPR.

Here are a few videos of my idle and AFR's. Please help me figure this out. I really want to get this fixed before I get my MS from Scott.

Thanks for your time.

http://i19.photobucket.com/albums/b1...h_MVI_6171.jpg
http://i19.photobucket.com/albums/b1...h_MVI_6172.jpg
http://i19.photobucket.com/albums/b1...h_MVI_6173.jpg
http://i19.photobucket.com/albums/b1...h_MVI_6176.jpg
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Zabac 03-14-2008 10:06 AM

your settings are wrong...it is impossible to idle at 4-5 AFR's


edit-im not gonna delete what i said, but i am so wrong...i didnt watch the videos until after i posted...sorry

levnubhin 03-14-2008 10:17 AM

lol, have you had your coffee yet? Where the heck did you get 4-5 afr?
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Braineack 03-14-2008 10:19 AM

looks pretty normal to me.

DammitBeavis 03-14-2008 10:23 AM

If you're using a mass-air system, it almost sounds like an intake leak. I don't have sound here at work so I can't hear how it's running. It SHOULD go full lean when you decel in gear (overrun shutdown).

Zabac 03-14-2008 10:24 AM


Originally Posted by levnubhin (Post 228008)
lol, have you had your coffee yet? Where the heck did you get 4-5 afr?

thats what the screenshot looks like to me, maybe im blind, but it says 5.8 and one says 5.9 and the third says .4 etc.
nevermind, lol

levnubhin 03-14-2008 10:25 AM


Originally Posted by Braineack (Post 228009)
looks pretty normal to me.

Is that because I dont have any real engine management at the moment?

My fuel mileage is realy bad and idle is all over the place.
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levnubhin 03-14-2008 10:27 AM


Originally Posted by DammitBeavis (Post 228010)
If you're using a mass-air system, it almost sounds like an intake leak. I don't have sound here at work so I can't hear how it's running. It SHOULD go full lean when you decel in gear (overrun shutdown).


Yes I still have my mass. I bet there could be an intake leak its not the best setup. Anyone else think so?
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hustler 03-14-2008 10:27 AM


Originally Posted by whaaamx5 (Post 228012)
thats what the screenshot looks like to me, maybe im blind, but it says 5.8 and one says 5.9 and the third says .4 etc.
nevermind, lol

word life

Braineack 03-14-2008 10:27 AM

if you can unplug the iac and the idle isnt effected then its bad...whats your vacuum at idle?

levnubhin 03-14-2008 10:28 AM


Originally Posted by whaaamx5 (Post 228012)
thats what the screenshot looks like to me, maybe im blind, but it says 5.8 and one says 5.9 and the third says .4 etc.
nevermind, lol


Thats because the camera catches the lights flickering on and off.
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DammitBeavis 03-14-2008 10:31 AM

That is a wideband right?

16:1 idle doesn't sound normal to me. Does it idle rough? Any cause of missfire including
too much fuel will make the O2 sensor read lean.

levnubhin 03-14-2008 10:34 AM


Originally Posted by Braineack (Post 228018)
if you can unplug the iac and the idle isnt effected then its bad...whats your vacuum at idle?

Well I jut wend and unpluged the iac at idle and the idle dropped significantly. Plugged it back in and the idle went back up. Vacuum at idle is 19-20.
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levnubhin 03-14-2008 10:36 AM


Originally Posted by DammitBeavis (Post 228021)
That is a wideband right?

16:1 idle doesn't sound normal to me. Does it idle rough? Any cause of missfire including
too much fuel will make the O2 sensor read lean.


It only idles rough when the idle itself is very low, otherwise no. Car runs strong, no missfire or hickups of any sort.
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DammitBeavis 03-14-2008 10:41 AM


Originally Posted by levnubhin (Post 228023)
It only idles rough when the idle itself is very low, otherwise no. Car runs strong, no missfire or hickups of any sort.

I would expect an actual 16:1 idle to be rough. Did you mess with any of the crankcase vents that would cause the PCV system to suck in unmetered air? Pull the PCV and stick your finger over the end of it so that the intake can't get air through it. See if it changes the idle.

levnubhin 03-14-2008 10:51 AM


Originally Posted by DammitBeavis (Post 228026)
I would expect an actual 16:1 idle to be rough. Did you mess with any of the crankcase vents that would cause the PCV system to suck in unmetered air? Pull the PCV and stick your finger over the end of it so that the intake can't get air through it. See if it changes the idle.

No change.
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DammitBeavis 03-14-2008 11:04 AM

Where is the Wideband sensor located in the exhaust?

levnubhin 03-14-2008 11:16 AM

after the cat delete "test pipe". Yes it is on the top of the pipe.
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Saml01 03-14-2008 11:25 AM

Could the base idle pressure on the AFPR be set wrong?

Can a car even idle at 5:1 afr?

Whats having me scratch my head is that you say it varies, from rich to lean at idle.

Any pattern? Is it correlated to something? Engine temp perhaps?

DammitBeavis 03-14-2008 11:31 AM

I'm having a hard time getting past the smooth idle with a 16:1 mix. Can anybody else here idle smooth at 16:1? I normally have to go a touch richer than 14.7 to get a nice idle.


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