Hi folks,
New guy here with my second post after my intro. Getting my first D1 road-worthy and I've got some smelly exhaust. Got the scanner hooked up today and came back with what looks like some bad sensors? Learning my way around the scanner and the data. I'm attaching the output below if somebody could give me a quick read or recommend what else I should dig into?

• Looks like the passenger side front and back?
• Should I inspect wires, clean connections first, or just grin and replace them?
• I've been reading the boards and know it's recommended to replace all at once. Could I get by with just bank 2?
• Either NTK or Bosch (still digging for exact model #s)
• I noticed a small exhaust leak before the muffler. Would that have any effect?
• I couldn't get any info from the MAF. Should I be able to?

Thanks in advance! I've only been running errands in town cause it's running rich. Looking to getting some miles in.

Jesse

 

OK. The very first thing you should do is buy a OBD dongle and get a smartphone app to see the live data as it happens. If you have an Apple phone you will use the app "OBD Fusion". If you have an Android, "Torque" is the app you want.
This one look OK...



On the dongle side there are two flavors....bluetooth and wifi. At one point long ago Apple only supported wifi. I believe that has changed and the bluetooth models are now compatible with iPhones. Either way, go to Amazon and select a $30 ELM327 OBD dongle. Just pick the one with the most reviews and stars and read carefully to make sure it is compatible with your phone. This will be the best $35 you will ever spend on your truck and save you thousands in time and money (shop diagnostics) over the course of your ownership.



It is recommended that you replace the O2 sensors in pairs.... in other words, replace both upstream sensors together. Don't worry about the down streams at this point, they are not actually involved in the air/fuel mix calculation.

FWIW, it looks like both your driver side (bank 1) upstream sensors are toast because the voltages did not seem to change at all which is unrealistic. On the passenger side (bank 2) it looks like your upstream might be alive, but the downstream looks dead. I am not one to 'throw parts' at problems but am fairly confident your fix will eventually involve replacement of the upstream sensors.

The best and most cost effective sensors for a D1 I have found are ....NTK 25044. All four are the same on the D1 (D2 is a different arrangement)

Once you have those tools you will see the long and short term fuel trims shift in real time as the voltage from the O2 sensors change.

The other thing to check for is corrosion around your engine ECU. It is a common ailment. I don't think this is the source of your problem, but it is one of the things to do on the checklist that is free and eventually you will get around to it. So do it now while you wait for the OBD dongle and sensors.

 

Walt, The data I attached is from a cheapo OBD2 from Amazon. I bought the Bluetooth version and hooked it to an old laptop. I'm going to swap for an iPhone-friendly version.
All the sensors move when in live mode. I'll have to look more into the ranges to see what is the norm. I do have an 1138 code now too.
Going to order the sensors and tool. Thanks for the recommendation. There were a few I had bookmarked the NTK being one of them. I'll check the ECU location but this truck is fairly rust-free.

I grabbed the D1 manuals from your link. Thanks again from a former NYC resident!

Jesse

 

@WaltNYC I have one more NTK 25044. Should I buy one more and replace the downstreams? Truck has been running pretty good what would be the benefit? Thanks! Ordering an Ultraguage too.

 

If you don't have a check engine light (CEL) on the dash, leave it alone.

 

Here's an idea. A good check is to watch the voltage signal from the o2 sensors with the OBD scanner. When working properly, the voltage should oscillate from near zero to near 1 volt. When cold the voltage starts near zero then climbs gradually before starting to oscillate. I had a problem with one o2 sensor not oscillating and driving the fuel trim rich on its bank. It did not trip the CEL. When I replaced the o2 sensor, the oscillations began again and the fuel trim self adjusted, just like it's designed to do.

The downstream sensors should not move to the same extremes as the upstream sensors. Their voltages should be more towards the middle of the range. That is how they monitor the cats.