Two Sensors Die at Once? 98 v70 T5

[WagonLagan]

Well. I replaced the IAC with a used one. Naturally it wanted to screw with me so it ran great for about 10 minutes! Then, right back to the exact same nonsense.

Unplugging it didn't seem to help anymore either. ???? Maybe because it's in limp-home mode again?

The only guess I have left is the wiring/electrical issue. Think I'll have my indie test the electrical signals/connections to the TPS and IAC.

Does that make sense? What else should I have them check if that fails? MAF?

[scot850]

Have you tried swapping the MAF for another one either good or bad to see if the problem goes away or changes?

Neil.

[WagonLagan]

I don't have access to another MAF unfortunately. They may have one at my indie, so I can put that #1 on the list to test first if you think it sounds strongly like MAF issues.

If I unplug the MAF, should it act the same or no?

[sleddriver]

Realize that as our old cars age, the wiring insulation inside the harness can become defective, the copper will corrode, and intermittent shorts can occur due to vibration and hot/cool cycles. Been there done that with the ECT, crank & camshaft position sensors. Just because you replace a sensor, doesn't mean the wiring leading to that sensor is OK. You have to check.

You can search my post on the ECT for an example.

[erikv11]

I don't have access to another MAF unfortunately. They may have one at my indie, so I can put that #1 on the list to test first if you think it sounds strongly like MAF issues.

If I unplug the MAF, should it act the same or no?

I didn't re-read the front of the thread but to answer your question directly: If the problem is the MAF, then with the MAF unplugged the symptoms should go away. The car runs just fine with the MAF unplugged, except a little rich. Plug and unplug it with the engine off, not running.

[WagonLagan]

Realize that as our old cars age, the wiring insulation inside the harness can become defective, the copper will corrode, and intermittent shorts can occur due to vibration and hot/cool cycles. Been there done that with the ECT, crank & camshaft position sensors. Just because you replace a sensor, doesn't mean the wiring leading to that sensor is OK. You have to check.

This is my most recent thought on what the root cause is, but electrical systems is my weakest subject with cars.

Do you know if the TPS and the IAC are on the same wiring?
Or are the TPS and the Baro Sensor on the same wiring?

If one or both of those, that might explain the weird code combinations.

[WagonLagan]

If the problem is the MAF, then with the MAF unplugged the symptoms should go away. The car runs just fine with the MAF unplugged, except a little rich. Plug and unplug it with the engine off, not running.

I will experiment with this tomorrow to hopefully rule-out the MAF, before my indie throws another expensive part at the car. -.-

[sleddriver]

Do you know if the TPS and the IAC are on the same wiring?
Or are the TPS and the Baro Sensor on the same wiring?

If one or both of those, that might explain the weird code combinations.

No I don't.
A visual inspection is necessary to see if the insulation is in good shape.