Computer Issue? | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Computer Issue?

rbdriver25

New Member
Joined
March 30, 2020
Messages
4
Reaction score
0
City, State
Spartanburg, SC
Year, Model & Trim Level
1997 Explorer Eddie Bauer
I’ve got a ‘97 Explorer with the 4.0 SOHC. I’ve got a check engine light that comes up as both bank one and bank two running lean. When I look at live data, all of my O2 sensors show 0, which explains the code for running lean. However, live data also shows my fuel trim as -100. Seems to me that if the computer thought the engine was lean, fuel trim numbers should be positive, and never anywhere close to 100 either direction. Is it possible that just changing my O2 sensors could fix the problem, or is it likely that my ECU is bad?
 

Attachments

  • image.jpg
    image.jpg
    24.4 KB · Views: 86
  • image.jpg
    image.jpg
    24.7 KB · Views: 90
  • image.jpg
    image.jpg
    23.9 KB · Views: 93



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





are you having any related symptoms or just hate seeing the cel all the time? anyway when i had my 97 it used to have cel for the o2 sensors alot but i never pulled the data. wasted a bunch of money changing the o2 sensors and it ended up being the orings on the plastic upper intake manifold. i couldn't get the o2 sensors out so i took it to a shop and requested they get changed. when i picked it up the mechanic told me it was pretty common issue with those orings and to save myself some money and change them myself. was like 11 bucks for the orings and maybe 30 min or so worth of work.
 






I’ve got a ‘97 Explorer with the 4.0 SOHC. I’ve got a check engine light that comes up as both bank one and bank two running lean. When I look at live data, all of my O2 sensors show 0, which explains the code for running lean. However, live data also shows my fuel trim as -100. Seems to me that if the computer thought the engine was lean, fuel trim numbers should be positive, and never anywhere close to 100 either direction. Is it possible that just changing my O2 sensors could fix the problem, or is it likely that my ECU is bad?
A bit hard to believe that your engine is running without any fuel :) My guess would be that your scanner is not reading the trims correctly (or incapable of reading them and substitutes some fixed value). Other the CEL on, what are the symptoms?
 






I’ve got a ‘97 Explorer with the 4.0 SOHC. I’ve got a check engine light that comes up as both bank one and bank two running lean. When I look at live data, all of my O2 sensors show 0, which explains the code for running lean. However, live data also shows my fuel trim as -100. Seems to me that if the computer thought the engine was lean, fuel trim numbers should be positive, and never anywhere close to 100 either direction. Is it possible that just changing my O2 sensors could fix the problem, or is it likely that my ECU is bad?
This is old and becoming buried knowledge but some 97+ explorers have a bug where OBD readers can't read the live data. Switch to Forscan and that reads the internal parameters (there are 100s of them, no loss not being able to use an OBD reader today). Forscan is free and good adapters are 20$. This may have been an issue 15-20 years ago where a good scanner cost a fortune.
 






are you having any related symptoms or just hate seeing the cel all the time? anyway when i had my 97 it used to have cel for the o2 sensors alot but i never pulled the data. wasted a bunch of money changing the o2 sensors and it ended up being the orings on the plastic upper intake manifold. i couldn't get the o2 sensors out so i took it to a shop and requested they get changed. when i picked it up the mechanic told me it was pretty common issue with those orings and to save myself some money and change them myself. was like 11 bucks for the orings and maybe 30 min or so worth of work.
Interesting. I did start having the issue after I took off my upper intake manifold to change my thermostat housing. Honestly, I was being cheap and didn’t bother replacing any gaskets, other than thermostat gaskets.
 






A bit hard to believe that your engine is running without any fuel :) My guess would be that your scanner is not reading the trims correctly (or incapable of reading them and substitutes some fixed value). Other the CEL on, what are the symptoms?
Oh it definitely runs on fuel. My wallet feels the effects of that. But no symptoms really. My gas mileage is actually within or better than the EPA estimates, which is impressive for having almost 390,000 miles on it.
 






This is old and becoming buried knowledge but some 97+ explorers have a bug where OBD readers can't read the live data. Switch to Forscan and that reads the internal parameters (there are 100s of them, no loss not being able to use an OBD reader today). Forscan is free and good adapters are 20$. This may have been an issue 15-20 years ago where a good scanner cost a fortune.
Hmm...I was not aware of that bug. I don’t suppose a more expensive scanner would help? The one I own is a $30 piece from Walmart, but I work for Advance Auto and the one the store uses is the top of the line of what we sell.
 






Might want to start by checking the plastic vacuum hoses. Over time, they get brittle and break or can get holes in them from riding against hot objects like the exhaust manifold. O-Rings last about 80,00 miles or about 10-12 years. Heat are there worst enemy.
 






Hmm...I was not aware of that bug. I don’t suppose a more expensive scanner would help? The one I own is a $30 piece from Walmart, but I work for Advance Auto and the one the store uses is the top of the line of what we sell.

If it accesses generic OBD-II data, it may not work. You need a scanner that reads direct from the ECU. Whatever Advance sells likely won't read it, they sell generic OBD scanners, but if you can try it, go for it!
There are many adapters around but here is one: https://www.amazon.com/dp/B01F0GVBWY/ or https://www.amazon.com/dp/B06XJL31Z7/
Forscan software is free. It can also read things like ABS wheel sensors, 4x4, transmission, etc.
 






If it accesses generic OBD-II data, it may not work. You need a scanner that reads direct from the ECU. Whatever Advance sells likely won't read it, they sell generic OBD scanners, but if you can try it, go for it!
There are many adapters around but here is one: Amazon.com: OHP ELMconfig FORScan OBD2 USB Adapter for Windows, Ford Diagnostic ELM327 Coding Tool with MS-CAN / HS-CAN Switch: Automotive or Amazon.com: OHP Wifi FORScan OBD2 Adapter for Windows, Android & iOS, Ford Diagnostic Scan Tool, ELM327 Code Reader, MS-CAN / HS-CAN Switch: Automotive
Forscan software is free. It can also read things like ABS wheel sensors, 4x4, transmission, etc.

So if a module in the CAN-BUS. Has an issue this will be able to pull that information from the vehicle? How Bout any UBP info?
 






So if a module in the CAN-BUS. Has an issue this will be able to pull that information from the vehicle? How Bout any UBP info?
Hope you get your answer here, but please be aware that you are posting this on the 2nd Gen (1995-2001) Explorer forum, and our vehicles don't have the CAN Bus.
 






Hope you get your answer here, but please be aware that you are posting this on the 2nd Gen (1995-2001) Explorer forum, and our vehicles don't have the CAN Bus.

Yeah I didnt realize that or know 2nd gen had no can-bus. It was intended for the guy who posted the links for the scanners. But I believe I did see a Forscan thread before. I will search for that. Thanks 1998Exp
 






So if a module in the CAN-BUS. Has an issue this will be able to pull that information from the vehicle? How Bout any UBP info?
Our 95-01 trucks don't have CAN or UBP. Just Fords PWM protocol for the powertrain and ISO for the ABS brakes (and maybe the Airbag system).
Forscan is excellent with CAN though. If you notice the adapters have a switch, there are actually two CAN busses on newer Ford Vehicles, high and medium speed (for accessories , entertainment, etc). Some adapters can autoswitch.
UPB I think is only the dealer scan tool.
 






I would start by replacing the intake manifold gasket, and of course examine any vac lines for possible breaks, cracks, or just popped off their connections.
 






Back
Top