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71 C20 gets a 5.3

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I don't know much, so I can only offer this: since changing things, have you reset the computer or at least disconnected the battery for a few minutes? You are dealing with what scares me the most about my C10/LS swap. I don't like computers, but I need the newer drivetrain.
 
Cili said:
How are you testing signal from the MAF? With it plugged in it unplugged?
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With it plugged in. Poaitive probe I the back of the plug negligible to yes ground on the battery.

I have poked around at ls1tech but haven't asked. I'll give it a try.

Even with these issues I would still do the swap again, it's probably something stupid everything said and done. Most of the time a computer makes it pretty easy to diagnose.
 
Can you read live data? If so see what the map sensor is reading key on engine off. If it is skewed it could make the MAF think it's getting the wrong amount of air. Other than that I'm out of ideas.
 
Unfortunately I can't. I should have a bunch if time to dive into it tonight, I have a couple things I want to try from threads on ls1tech
 
Here is the freeze frame data I got the last time I took it on a test drive. Isnt the MAF value low?
Fuel Sys 1 CL
Fuel Sys 2 CL
Calculated Load 8.6%
Coolant Temp 188.6*F
STFT B1 -23.4
LTFT B1 -5,5
STFT B2 13.3
LTFT B2 24.2
Map 20.4 inHg
RPM 1329
MPH 34
MAF 2.6Lb/min
TPS 19.2%
 
71 C20 gets a 5.3 - P0101 MAF Code issues Post#143

Seems like it. It should pull about that much or a little more at idle. Clogged air filter?

Edit: That doesn't seem right either because if it is not seeing much air coming in it should be taking fuel away like bank 1 is but bank 2 is adding a ton of fuel.
 
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I guy on ls1tech suggested the 02 sensors were on the wrong side, but I verified they are right. Its weird the fuel trims are almost opposite bank to bank. I might break down and buy a better scanner so I can see live data
 
Do you know if anyone has ever tried taking one of these swap into a dealership? If anything, just to get a diagnosis and plan of attack. Or they might cry and send you away cause their "technicians" don't know chit.
 
K85 Octane said:
Do you know if anyone has ever tried taking one of these swap into a dealership? If anything, just to get a diagnosis and plan of attack. Or they might cry and send you away cause their "technicians" don't know chit.
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I think there is too many variables for them deal with. You might be able to get them to plug it in ad give you real time data, but you could also just spend the $200 and buy a scanner that will do the same thing.
 
Hey NorCal, what changes have you made during the swap? Meaning: is the computer re-programmed, smog stuff and software, any other changes you've made from donor vehicle to your truck? Also, did you have a chance to drive the donor vehicle or hear it run?

Sorry if you already went over this. Just trying to narrow it down and also help my own swap :D
 
a 200$ scanner wont be nearly as accurate, live time, or ect as the ones the dealership techs use, as theirs costs at the very least 4 times that. Iv used the latest and greatest Snap On scanners, and the cheapie ones you can get dont even come close to what you will need to dive that deep into the engine. Sure they will get you in the ballpark, but that sometimes is only close enough for hand grenades.

Has an intake leak on the one side crossed your mind? Or perhaps a pinched wire or short causing such chaos. As the LTFT and STFT on one side, with your scanner, is an average of all 4 injectors, you may have one dying out on the one side causing the system to richen up to compensate, and thats where the nicer scanners come into play, as you can see exactly what each injector is pulling for volts and so on. Which can be handy dandy. Also, try pulling the plugs and see what they say.
 
K85 Octane said:
Hey NorCal, what changes have you made during the swap? Meaning: is the computer re-programmed, smog stuff and software, any other changes you've made from donor vehicle to your truck? Also, did you have a chance to drive the donor vehicle or hear it run?

Sorry if you already went over this. Just trying to narrow it down and also help my own swap :D
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The computer has been reprogrammed with no emissions stuff and for the manual transmission. I double checked with the tuner and it's done for te injectors and all that. It's running headers and an open element intake (dry style so that's not messing up the maf) but other than that it's stock. I have read the Bosch o2 sensors have trouble keeping up with more performance stuff, but the engine is pretty mild.

I bought it already pulled from a reputable wrecker, it had good compression numbers and was pretty clean. It was from a 2003 silverado 1500.
 
454Sub said:
Has an intake leak on the one side crossed your mind? Or perhaps a pinched wire or short causing such chaos. As the LTFT and STFT on one side, with your scanner, is an average of all 4 injectors, you may have one dying out on the one side causing the system to richen up to compensate, and thats where the nicer scanners come into play, as you can see exactly what each injector is pulling for volts and so on. Which can be handy dandy. Also, try pulling the plugs and see what they say.
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I looked for a leak with no luck, swapped the intake gaskets just in case. I will look into the injectors, I think I know a guy with a decent scanner. I swapped the plugs last week, they were in good shape just lots of carbon build up from it running so rich. I am leaning towards a short or cracked wire, just haven't had much time to dive in. I rewired all the 12v ignition hot wired last week, hopefully it's just a loose ground somewhere cause a cracked wire is going to be hell to track down.
 
As we all know, grounds will wreak havoc on a FI system. I always use the battery terminal grease stuff on mine so rust cant form underneath the ground straps and lessen the effectiveness of it. Not sure on your wheeling conditions, but here, water, mud and rust is all we have, so the jizz under the straps really did help me.
 
454Sub said:
As we all know, grounds will wreak havoc on a FI system. I always use the battery terminal grease stuff on mine so rust cant form underneath the ground straps and lessen the effectiveness of it. Not sure on your wheeling conditions, but here, water, mud and rust is all we have, so the jizz under the straps really did help me.
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We are pretty spoiled where I live in California, it's pretty dry so rust isn't really an issue. This truck hast seen much as far as wheeling goes either, my driveway and street are pretty bumpy though:D. They shake the hell outa the thing. I am hoping I will get off early tomorrow and can get some truck time.
 
I think I might have figured it out, but ten it started pouring. I ran the ground for the passenger o2, maf and a few other things to the firewall not the head like it came factory. I am running battery to block and battery to frame grounds but the block to firewall and frame to firewall stuff is missing. The surface wasn't all that clean either. Hopefully that's it...
 
newer efi stuff needs its grounds back to 1 central point and easy path to the computer .

its so crazy these days some have isolated grounds for each sensor .

and some are now switching grounds rather than hot side.
 
Well **** that didnt do it. I was looking at the limited live data my scanner does and it seems to stay in open loop
 
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