Electrical Maf / 02 issues

TOOLOW91

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So I have this 90LX I wire tucked that didn’t run when it got here . Cranked like a dead battery . Long story short the battery ground in the trunk was no good so I fixed this . I was not the one who relocated it originally .

Car runs but won’t idle for anything breaks up etc . 306 , performer heads , Edelbrock intake , unknown cam , long tubes . 24lb injectors , A3m ecu , bbk mass air meter with the adapter plug for it .

Do base idle reset and clean the iac motor . Car runs for a few then starts running real funny and dies again . Won’t hold idle and breaks up .
Knowing it has no 02 sensors or harness I order one from Ron Francis . Pin it for a 90 5 speed car . Check pin 46 on ecu and make sure it doesn’t have voltage when trying to crank . Good to go .

Hook up ecu fire the car up it idles up like it should seems it idling Decent now . Go to back out of the driveway fire it up and it won’t even start . Have to goose throttle runs like it’s got a fuel miss or pressure issue which it doesn’t (gauge on regulator ) . If I’m reading the light righ

In diag mode it will run and hold idle like it should as well .

So what do you guys think ? Either way I am ditching this meter and putting a pro m on the car for him.

Run codes -
KOEO
85- Canister purge - it isn’t there no big deal
66- No mass air signal
31- canister / egr both aren’t present
KOER
26- mass air
41-Lean fuel mixture
91-Oxygen sensor problem / fuel pressure out of range / injectors out of balance
33- egr / canister - again not present

View: https://youtu.be/XPbnEz_rZU0


View: https://youtu.be/QkS6vDjxJy8


EC34A7B3-AB13-4534-A4D8-05E83D076183.jpeg
D7F50A11-9354-4409-AC57-3D53B17E7CE5.jpeg
 
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TOOLOW91

If you're the village idiot what's that make me?
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So I test the maf signal . Has 12v, ground and ref signal . Do continuity test between ref and return and it passes that as per another thread .
Maf signal at idle is only .38 or so when I can get it to idle . Over 10k ohms

02 sensor harness is jumpered like a 90 because the car and harness are a 90 .
5C6B5121-2F65-4F08-A079-BB8DC6DF2429.png

Also I found this while trying to check the maf . They had issues with the connector not being tight or staying and this apparently was the fix .... silicone on the pin lock to hold it in .
FE6EA138-B562-45FF-BAB5-1A059DF74C6B.jpeg
 
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2000xp8

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I've not seen much good out of meters on foxbodys that needed an adapter harness, that's why my buddy kept the selectable pro M around (now made of unobtainium) for testing.
Never much liked anything BBK either, because from what i've seen, all their meters are rebadged.
As a matter of fact (i'd have to look), i think my meter is an SCT rebadged as a BBK that was taken from a foxbody that wouldn't run right.
 
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TOOLOW91

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I've not seen much good out of meters on foxbodys that needed an adapter harness, that's why my buddy kept the selectable pro M around (now made of unobtainium) for testing.
Never much liked anything BBK either, because from what i've seen, all their meters are rebadged.
As a matter of fact (i'd have to look), i think my meter was an SCT rebadged as a BBK that was taken from a foxbody that wouldn't run right.
My thoughts exactly , which is why I went ahead and had him just get a pro m . If we had stock injectors and a stock meter it would’ve already been back in the car because that’s really all it needs . Pro m is all I’ve ever used once I learned what was what .
 

TOOLOW91

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I had a feeling this thread would be so long winded there wouldn’t be very many replies .
 

2000xp8

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I had a feeling this thread would be so long winded there wouldn’t be very many replies .
I can help string it along with some sarcasm?

You need a tune...
It is indeed the universally accepted solution when you don't know WTF you are doing.
 
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TOOLOW91

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I can help string it along with some sarcasm?

You need a tune...
It is indeed the universally accepted solution when you don't know WTF you are doing.
Damnnnnn I didn’t even think of that . I knew I was missing something
 

Boostedpimp

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I had a bbk meter once.. brand new out of the box ran like poo. Only reason why I had it was to replace my prom that died and needed something quick. Ended up going with a pmas and have used them on a few cars now with great results. Like mentioned bbk products seem to be crap and always have been in my opinion
 
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TOOLOW91

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Very, very dumb question from me to you- have you verified timing?
Yup first thing I did was set base timing . But I’m glad you mentioned it we were in same thought process
 

RaggedGT

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Yup first thing I did was set base timing . But I’m glad you mentioned it we were in same thought process
I’ve been trying to think of something useful to post-to add to this thread about the issues you are having-After looking through wiring diagrams, and finding out that a 9’ fox wiring harness is unique to a 90’ model fox only. It would have to be in the wiring, right:shrug:
I pulled some diagrams (thanks @jrichker ) that I’m sure you have already seen-
D7EFDFAA-4208-4319-9515-E706D1083698.gif
FE124913-8D36-4D29-B2EA-DE4A31F4A992.png
A96E3BFD-477E-42A9-B7AB-FE5EEF865C13.png

As well as a maf testing diagram, again I’m sure you have seen. I also found a thread from the master himself with some might be useful info-


Apologies in advance if none of this helps-when I find some more,I’ll be back lol
 
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TOOLOW91

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I’ve been trying to think of something useful to post-to add to this thread about the issues you are having-After looking through wiring diagrams, and finding out that a 9’ fox wiring harness is unique to a 90’ model fox only. It would have to be in the wiring, right:shrug:
I pulled some diagrams (thanks @jrichker ) that I’m sure you have already seen-
D7EFDFAA-4208-4319-9515-E706D1083698.gif
FE124913-8D36-4D29-B2EA-DE4A31F4A992.png
A96E3BFD-477E-42A9-B7AB-FE5EEF865C13.png

As well as a maf testing diagram, again I’m sure you have seen. I also found a thread from the master himself with some might be useful info-


Apologies in advance if none of this helps-when I find some more,I’ll be back lol
All good bro I appreciate it , I looked at those and used it for my maf testing . I’m thinking in that adapter plug something is going on . I looked at those . 90 is unique in that it has the first year for air bags but is still like an 89 with the 2 plugs up on the fire wall , maf has voltage , gnd , and ref voltage .
Over 10k ohms on the signal ref and return checked together

it’s only about .38-.4 v though with the car running .
It’s seeing something it doesn’t like because in diagnostic mode jumped as you can see in video it holds a idle doing the test and then it dies as soon as the jumper is pulled
 
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TOOLOW91

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New sensor - starts stalls . Get it run on the 2nd or 3rd try . Have It running the car seems to be running cleaner and boom once it gets some temp in it you go to drive it and it’s breaking up popping has no power again , unplug 02s same thing nothing changes . I’m starting to think it has a computer issue . This ecu was chipped at one time the chassis had a blower in it before this person bought it as a roller
 

TOOLOW91

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Messed with the car some more , I rememberd the ecu ground was never there when I tucked it . I don’t know why it was an after thought but it was out of sight out of mind . I pull it out of the harness and ground it . Nothing changes . What I do notice is when I let the thing sit for hours and fully discharge the car will start and run very very clean and normal .
After 5-10 min of running you shut it and restart it and it will not hold and idle . It pops and sputters / breaks up .
Only other time it will run normal is if the ecu is Jumped to read codes . So I’m leaning toward this again being an ecu issue . I am getting a spare this weekend . I don’t see anything apparent though .
01C1E488-DD7A-407F-80F8-F6C174E6E170.jpeg DE61DB1E-DE25-4B15-8DED-AEAF943FC258.jpeg
 
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TOOLOW91

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Meant to post this . Anyone think that bad boy leaked out ?
4BB0EE85-7E5B-41D2-93D9-097623F59C99.jpeg
 
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TOOLOW91

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Well , I tried another a9l and the car runs identical . I have to say I’m pretty stumped . Ect reading ok . Maf has its readings ( brand new pro m)

02s hooked up or disconnected doesn’t matter . Fuel pressure seems ok unless the gauge is wrong but I doubt it .
 

TOOLOW91

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FIXED !!!!! The maf plug he had was no good . In a last ditch effort I went and cut the harness and plug off my old harness and put it on his , car runs like a dream .
 
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TOOLOW91

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Always the simple things huh? glad you found it
Threw me off because I had a reading at one point then I went through it again and didn’t . So I had a feeling with this janky harness they had for the maf . I Cut mine off my old harness and as soon as I turned the key it fired off like a different car
 
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