Different map sensors

[msbweiland]

Have a 17 l83 from a 2wd Silverado and 6l80e. My map sensor is on the intake. According to the vcm editor it was telling the pcm that the map was on the throttle body. Is that normal on the l83?s? For some reason I?ve never seen one like that before.
Car will start and idle, but not good throttle response. Not enough to try driving it. I can see why if it was thinking the map was in the wrong spot. Anything else I should look for when changing the parameters to the correct map sensor location? Any tips on tuning the off idle and mid throttle for a newbie?

[5FDP]

What do you mean it says its on the throttle body?

All the 5.3/6l80e files I have show NA-TIAP for map sensor config. I think you have other problems if the engine is completely stock and it's running a stock MAF with a stock air box/tubing.

[msbweiland]

Wasn't sure if it was correct or not when it showed NA-TIAP on the MAP sensor setting on the editor. Tried both MAP settings, same deal with the idle stumble. Have more questions on the VCM scanner I'll put in a different thread.

[cadillactech]

Is this a swap?

In stock form GENV V8's, there is a TIAP, Throttle Inlet Absolute Pressure sensor which refers to the pressure sensor built into the MAF sensor. Sometimes it is called the BARO sensor. The ECM uses this and the MAP sensor in the intake manifold to calculate pressure ratio.

[msbweiland]

Yes it's a swap. 17 5.3 from 2wd silverado with 6 speed auto into a 72 chevelle. The place I bought the setup from in Houston has made it a nightmare. Sent me the engine a month late, sent a 2016 harness instead of the stock 2017 crammed in a box, DIY cold air intake with no MAF, Wrong headers that wouldn't even come close to fitting, etc...He also installed a corvette intake and throttle body with the holly angled spacer to give better hood clearance.
Trying to get it sorted the best I can. MAF is from the parts store and is supposedly for a 17 silverado 5.3. I bought a 2017 harness straight from GM so the pins @ the pcm would be correct and modded it myself to fire off the relay box like I do the rest of the swaps I have done in the past. I think the combination of different parts is throwing the whole thing off. I'm new to the L83's and just need to take some time to learn and a good starting point. I'll try to past the latest tune and see if it works. Title shows what I've tweaked. The rest is how it was read from the PCM the first time I plugged in the VCM editor.

hopefully this works for attaching...

72 chevelle 5 3 l83 2017 silverado 3 with trans fan and speedo 10 percent to cranking airflow an.hpt
72 chevelle 5 3 l83 2017 silverado 3 with trans fan and speedo 10 percent to cranking airflow an.hpt

[cadillactech]

You need to take some logs of all sensors and see what is reading, what isn't etc.

How many are wires coming out of the MAF?

[msbweiland]

I?ll look tonight and count and reply. It matched the wiring diagrams for the 17 5.3 I had and the connector is the same.

[msbweiland]

Here are a couple of logs I grabbed when I got home from work. One is my latest tuning try and the other is after me trying to disable the dynamic air and run strictly off the MAF. There is way more throttle lag when running off the MAF only. I'm sure that's where a lot of my issues are. Didn't seem like the MAF responded very much to throttle plate movement. I'll be playing with it over the next few days. Maybe I'll get lucky.
Throttle body has 5 wires on the harness and six pins inside the throttle body. One pin on the harness is empty. Pic attached of it and the part # on the throttle body. It has the angle adapter behind the throttle body to the intake. Tried spraying carb clean around it and the intake when it was idling in case I have a vacuum leak. No change in idle when spraying anywhere on the intake.
Haven't had a chance to play with the scanner software much beyond basics with it idling to get it in and out of the shop for glass and exhaust. Hopefully it gives the info we need to drill down to the core issue. if not, let me know what we need to look and and I'll try again.



72 chevelle 2017 silverado idle and try to rev with stumble and popping dynamic airflow disabled.hpl72 chevelle 2017 silverado idle and try to rev with stumble and popping.hplIMG_1174.jpgIMG_1175.jpg

[5FDP]

I already see a big problem with your o2 sensors. The one sensor is always at 800-900+ and the other at less than 100.

You are not logging your fuel trims so it's that does make it harder to see what they are doing. It's possible you have the harness backwards between the two sides. That will make the engine perform terrible.

No MAF or MAP, spark timing data either, hard to see what those are doing.

[msbweiland]

What PID's do you want for fuel trim on the log? I'll add them with the MAF, MAP and spark timing
You talking about the 02 sensors backwards? Only have the front sensors hooked up. No cats or rear 02. I'll put it on my hoist and check the connectors against the diagrams. I assume bank 1 is drivers side and bank 2 is passenger?

[msbweiland]

latest log after adding pids. Fuel trims seem to get worse as it runs. I'll check the sensors. Might the be right track.

72 chevelle 2017 silverado idle and try to rev with stumble and popping reset.hpl

[5FDP]

Yeah, if one bank is super positive and the other super negative on the trims it's usually the sensors on the wrong bank.

[msbweiland]

Here is the log after swapping the o2 sensors. I think I had them wrong for some reason. D side is now bank 1 and pass is bank 2. According to the wiring diagrams I had them swapped. Not sure why, must have missed it when I was installing the harness and pulled a bonehead move. Idles much better, throttle response when revving is a little slow, not sure if it'll be better once I'm moving. We'll see once it dries up outside and there isn't so much mud on the road. Thanks for that advice. Better to check the easy stuff first before doing brain surgery!

Where's the best place to go now? I'd like to get good throttle response and maximize my drivability. I'll let the next owner tune it for max power. For now I just want it responsive and have a nice smooth throttle.


72 chevelle 2017 silverado idle and try to rev with stumble and popping after o2 sensor swap.hpl

[5FDP]

Do you know what the fuel system is on this?

Is it always supplying the system with at least 58psi? The factory trucks would have a fuel pump control module that lowers and raises the fuel pressure but on swaps I'd want at least 58psi all the time to make sure that when the throttle is applied that it can't lean out.

They are also very particular about the intake size if the stock airbox isn't used. If the tube size is smaller or larger than stock that will change how it responds to the throttle.

[msbweiland]

It has an in tank pump (might be holly, can?t remember) and external regulator on the firewall. Fuel supply is about 68 psi on the gauge at the regulator.
Intake is a 4? diy cold air kit the engine guy gave me. Basically two silicone elbows and an k&n cone filter. You make the rest and get your own maf sensor. I used an aftermarket tube with the maf mount and ran it to the passenger fender. I may make a cold air box if I have time. For now it pulls air right next to the battery. Not the best place, but it?ll have to do for now.
I know I need to make up for the different intake. What?s the best way to do that so I can get it close to decent to start driving and playing with the tune? No wide band installed. Wasn?t sure if I?d need it for basic tuning for drivability. Not worried about raw power just a responsive stock tune is fine.

[msbweiland]

One more thing. I don?t think the intake and throttle body is stock. He said something about putting an shorter intake on it from something like a corvette. Bolts up fine.