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Wideband full lean car not even on

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Aaron_FTT

Proven Member
43
0
Jun 27, 2014
pueblo, Colorado
I never paid much attention to my wideband before starting the car so for all I know everyone's does this but it seems weird considering that I'm having bad AFR issues all of the sudden. I had some issues getting power to the starter after a tranny swap and ended up wiring in a push button. Maybe it has something to do with that but I have no idea. Point is, the wideband starts at the usual pre-crank 14.8, then it slowly starts leaning out until eventually I get the dreaded "- - -". Then I attempt to start the car and it takes 4-5 attempts before it kicks on. Any idea why my gauge would do that?
 
Well I kind of figured it should read full lean considering it's pure atmosphere but I never paid much attention to it so I wanted to see. I don't understand why I would be running lean as hell all of the sudden. Besides a blown tranny, the car was running perfectly. Then I swapped a new one in and suddenly my air fuel is f***ed. I'm just so desperate for answers at this point that I'm curious about everything. The car always started right up (at least until winter time. Dat e85.) And now it takes 5 attempts. It idles at like 15.2 and stays around there when driving lightly but the second I give it some gas (not even WOT) it completely leans out. I don't even want to think about going flat out with 30 pounds of boost so i have nothing to report on that front. Been scratching my head for a while now....

Another weird thing is that if I give it a tiny bit of throttle, it will climb the rpms smoothly until it hits the 2 step. But if I try to walk on the gas it's just fuel cut and misfiring left and right until it hits the 2 step. A LOT of backfiring at that point.[DOUBLEPOST=1411447173][/DOUBLEPOST]
  1. Meant to say it seems almost like it's misfiring and experiencing fuel cut. No confirmation on that. That's just the sensation it's giving off.
[DOUBLEPOST=1411462570][/DOUBLEPOST]Now the gauge is reading rich as hell with car not on. -______-
 
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Well it sounds like a sensor issue. Id start by logging O2 voltage and MAF Hz and do some research. Make sure those things are running well first.

EDIT: Sorry for the delay, this thread got lost on me
 
Well for shits and grins I pulled out the code reader despite the lack of an engine light. P0100. MAF circuit malfunction. Might be on to something here.
 
Depsite not having a CEL, your codes should show up in DSMlink. Theres a tab called DTCs. Check if you left the MAF wire unplugged or damaged the harness during your swap, check the HZ of the maf with a log, and try swapping it for a known working MAF.
 
The maf wire is connected. On the maf itself, and all the way to the ecu. Every connection appears solid. Unplugged it and as to be expected, it went rich as hell. It's a 3" gm maf btw. The UICP sat on the bench for 2 months while the car was being torn down, repaired and reassembled. I'm wondering if it could be as simple as cleaning it up. Guess it's worth a shot. I have dsmlink but never tinkered with it (left that one to jacks). I'll poke around in there and see if I can get my head around it.[DOUBLEPOST=1411697438][/DOUBLEPOST]Should of said the connections are physically sound. I'll throw the software on my laptop and check to make sure the ecu feels the same way
 
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Its not super complicated and its most useful aspect at first is the diagnostic abilities. For instance a GM MAF should see around 500HZ at idle if I remember correctly. So set up a log with MAF Hz as one of your captured values and start her up to see what range of values you get.

If youre getting a MAF circuit malfunction I doubt cleaning the MAF will help, but give it a shot. I would bet its a bad maf or wiring issue though.

Let me know if you need any help tinkering with Link. I highly recommend spending some time to figure out the basics
 
Thanks a million dude seriously. I'll probably be back with some more questions. Lol
 
Thanks a million dude seriously. I'll probably be back with some more questions. Lol

Cleaning the maf won't help. You have an open circuit. Which wires are you testing for continuity? There is more than 1 wire from the ecu to the maf. You also need to make sure you have power and ground. Find the correct schematic and double check everything for continuity from the plug to the ecu. Also verify that none of the wires from the ecu to maf do not have continuity to ground. The last thing would be to check the actual pins in the pigtail to make sure none of them are damaged.
 
Cleaning the maf won't help. You have an open circuit. Which wires are you testing for continuity? There is more than 1 wire from the ecu to the maf. You also need to make sure you have power and ground. Find the correct schematic and double check everything for continuity from the plug to the ecu. Also verify that none of the wires from the ecu to maf do not have continuity to ground. The last thing would be to check the actual pins in the pigtail to make sure none of them are damaged.

Duly noted sir. Gracious.
 
Ok well I'm seeing 33hz on the maf at idle. Engaging the 2 step for a couple seconds will get me to ~300hz
 
That shouldnt be happening. You want ~500Hz at idle. So there's your problem. Now its just down to figuring out where along the MAF circuit your problem is. Since you removed the MAF for your tranny replacement Id check all the wiring along there and the MAF itself.

P.S. How is Link treating you?
 
Roger that. I'll be pulling parts off tonight. Fingers crossed. How is link treating me? You mean how am I handling it? It's pretty straight forward much to my surprise. Really fun to mess with too. I'll be using it a lot more from now on.
 
So bit of an update, I got sick as hell and havent touched the car much until today. Well it turns out i had pulled up the wrong MAF value. I had the "MAF" value up and not the "MAFraw". Upon pulling the MAFraw value I can see that im at about ~550hz. I also pulled the UICP apart so i could clean the MAF, but the damn thing is spotless. Little oil but nothing alarming. Might just get a new GM maf cable and call it a day. Idk what else it could be. Everything else is checking out just fine.
 
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