V1 Back at it - maf sensor / among few others

[Batmonkey]

Been two years still can't figure this out. I also don't have as much time as I had before.

Maf sensor, with the maf sensor plugged in the car starts, then it chokes out and dies. If i unplug it can start and drive. These problems are consistent. I've tried 2 different maf sensors same thing, going to try a third just to be sure its not that.

Now the intermittent problems. Every now and then ill get low fuel, power steering, and gauge not working along with ob2 not being able to connect.

I have been focusing on the tan data wires, just can't decide which way to go with it.

 

[Batmonkey]

I had 62 between pin 6 and 14, but when my warnings came up i have 120 ohm between 6 and 14 on obd 2

 

[Gtstorey]

Obvious point to check for maf is wiring continuity for each pin of the maf to the correct pin of the ECM.

For intermittent data wire issues, about the only piece of advice to give is to tighten each connection point up all of the way through each side of the data pair. Unless you can figure out from a wiggle test which connection is bad. It’s possible it’s in a connected module but the odds are better on a loose connection and I don’t know of a way to check an intermittent internal module connection. There is a chance that a full module scanner would give some indication which module is the lfirst in the chain to fall out, but that would take some serious thinking and playing with to decide if it gives useful data. If by saying the obd won’t connect you mean a simple p code reader that only talks to the ECM, a higher end scanner may still connect to the other modules to again tell you where the break is.

 

[Batmonkey]

Obvious point to check for maf is wiring continuity for each pin of the maf to the correct pin of the ECM.

For intermittent data wire issues, about the only piece of advice to give is to tighten each connection point up all of the way through each side of the data pair. Unless you can figure out from a wiggle test which connection is bad. It’s possible it’s in a connected module but the odds are better on a loose connection and I don’t know of a way to check an intermittent internal module connection. There is a chance that a full module scanner would give some indication which module is the lfirst in the chain to fall out, but that would take some serious thinking and playing with to decide if it gives useful data. If by saying the obd won’t connect you mean a simple p code reader that only talks to the ECM, a higher end scanner may still connect to the other modules to again tell you where the break is.

Interesting, I will try a higher end scanner, I just ordered a proper probe kit for my multimeter for some better testing.

 

[Gtstorey]

Being able to back probe a connection without moving it around can be very helpful when looking for an intermittent connection.

 

[Batmonkey]

How do i check if ecm is getting consistent power and grounded correctly. The data wires show continuity when unplugged from ecm to ob2 port

 

[Gtstorey]

How do i check if ecm is getting consistent power and grounded correctly. The data wires show continuity when unplugged from ecm to ob2 port

If you are getting 120 ohms when you are having data wire issues, you have a break between the ECM and the OBD at that time. Or you have a problem with the power steering since that is where the other resistor is at. I'm pretty sure on these that the modules don't have to be awake or powered to allow the resistors into the network.

But to check the ECM power really needs the ECM to be readable so you can check it with a scanner. Beyond that its's just measuring voltages at all of the ecm feeds and a voltage drop test on all the grounds. You will have to check the wiring diagrams/pinouts to get all the +12v feeds and grounds.

 

[Batmonkey]

well im going to confirm its loose connection, i was able to recreate the problem. Not sure about maf sensor though. I think thats unrelated. When i start it up it chokes out stalls, if i run without maf plugged in in will run. I've back probed and circuit seems to be okay. I might need to tune it maybe?

 

[Gtstorey]

If there is a huge difference in how it runs plugged in or not plugged in, it probably isn't a tune problem. Tuning can help them run better, but most don't have any problem running stock tune. Assuming you have a typical intake piping setup.

Still seems more likely to be a swapped wiring problem. But could be wrong/bad maf. You do have it turned the right direction?

 

[Batmonkey]

If there is a huge difference in how it runs plugged in or not plugged in, it probably isn't a tune problem. Tuning can help them run better, but most don't have any problem running stock tune. Assuming you have a typical intake piping setup.

Still seems more likely to be a swapped wiring problem. But could be wrong/bad maf. You do have it turned the right direction?

Tried 3 different maf sensors. All do the same thing. Key on engine off reads 0 g/s and then I turn on maxs out around 1.8 before it stalls and chokes.

I am using a swapped ECU that I did relearn on

DF also did my wiring harness. Not that it means there cant be any issues with it.

 

[Rauq]

You do have it turned the right direction?

Second this.

 

[Batmonkey]

Second this.

Maybe that is backwords, but it does not fit any other way.

 

[Ross]

That arrow is showing the air flow direction... So yes, you have the MAF sensor in backwards.

 

[baustin]

Maybe that is backwords, but it does not fit any other way.

The MAF sensor might be in the metal pipe the only direction it fits, but can you flip the metal pipe ends around?

 

[Batmonkey]

The MAF sensor might be in the metal pipe the only direction it fits, but can you flip the metal pipe ends around?

Yeah, i just have to pull apart some of the wiring harness and i still dont know if it will reach if i do that. might have to cut an extend.

 

[SeanH]

The MAF sensor might be in the metal pipe the only direction it fits, but can you flip the metal pipe ends around?

yes sensor is installed correct in pipe, pipe needs to be flipped so arrow points toward engine.

 

[Batmonkey]

Yep, flipped it around and its working now. There was only way for it fit, the wiring harness could only reach so far, so i assumed that was how it was suppose to be! Pulled apart the wiring harness to get length

 

[Desert Sasqwatch]

Flipping the pipe also moved the MAP a little further away from the air filter, which gives slightly less turbulent airflow. If, when you start to play with your engine and find additional issues with idle or part throttle performance, an air straightener can sometimes help with better airflow over the MAF.

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[Batmonkey]

does anyone know what kind of pins the ecm connector uses? i am going to repin some connectors in there?

 

[Ross]

Mouser has the plugs for a Cobalt, but a auto recycle yard would be cheaper.
If you clean the ecm connector you sometimes can find a manufacturer name or part number in small print in the plastic casting. The BCM plug is made by Aptiv (Delphi).
AllData will also tell you some info about the connector, here is the BCM C2 plug, which is a 72-pin, using F Micro pins, size 64, and in Grey color plastic.