Quote:
Originally Posted by fishhouse4
I will check the connections on both ends.
The only two ideas my tech had was a new engine wiring harness (which would address those connections you just mentioned) OR a new DME. Both are stupid expensive...
Ok, help me here...this is what I don't get about the wiring/connection possibility:
It's just a wire, correct? It simply transmits the signal from point A (MAF) to point B (DME). Like... all or nothing, I would assume. So if the wiring or connections were damaged, then the signal wouldn't go to the DME. Which would be the exact same as having the MAF unplugged. So I would think in that case you would not get MAF signals to the DME regardless of if it was plugged in or not.
Or are you suggesting that the wiring/connections could be damaged in a way that could somehow degrade or corrupt the signal from the MAF??
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First, I think the fact that 4 different MAFs all give the same result means they're all fine. More likely for that to be true than for all to be bad.
When the MAF is unplugged, the control system figures out how to manage things (engine and AT) based on what sensors and system model it has. Many different ways to do something like this, not sure on specifics. But the fact that it runs just fine with the MAF(s) unplugged suggests the rest of the car is good. Engine, even the ECU.
Just a thought, maybe when it switches out of MAF closed loop mode or whatever it is, it also switches out some other sensors (e.g., O2 sensors) while it runs open loop. If you can get good info on how the open and closed loop circuits work, that may be helpful in deciding where else to look for the root cause.
On the connector / cable problem I suggested, I expect they are just wires. But for example, what if one of the (two?) pins with the actual MAF signal is bent / wire broken internally / etc. but other connections within the same connector / harness / cable are still good. Could it be that the ECU gets enough to think the MAF is there and working, yet it's actually getting garbage or no data on that line? Smarter fault detection methods could help in this, but maybe they kept it simple (for once, LOL).
So I would start with a careful visual inspection of the connector, making sure all the contacts look good. Then the easiest thing to do to check for a wire issue is to get the car running (with MAF connected, so running badly) and wiggle the wire as far as you can see it, hoping you intermittently restore something to make it run differently. Think about where an internal wire failure is likely to happen - at the connector, bends, any place it may have been pinched, etc.
After that, it's trying to find the other end of the MAF connector wires, and testing continuity through the whole wire.