93 Explorer - Check Engine Light
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
93 Explorer - Check Engine Light
My 93 Explorer 4.0L V6 has had very few problems over the last 17 years, but It's beginning to show some wear.The fuel gauge went out some time ago but I can live with the odometer as a substitute. The windows go down by themselves over time but a physical lift on the glass will get me thru the carwash. My last state required inspection in January showed a large increase in the Nox reading (976ppm@15mph from a previous reading of 756ppm).The limit is 990.
So I decided to clean the PVC valve and change the air filter last month. No problem until a week ago when the check engine light came on. I assumed I had a thermostat problem since I have to drive the car about a mile before that light comes on. Then when I shut down for about 30 minutes for shopping, etc., the light will not reappear until I've driven another mile or so. The light will always be off when I start the car each day.
Last Saturday I stopped by DriversEdge for their opinion. The mechanic hooked up the code reader (which he said was PRE-OBD1) and it read 137. So we agreed to change the fuel filter and clean the fuel rail, the fuel injectors and the throttle body. But on Sunday the light came on again after a mile or so.
So before I go back to DriversEdge for phase two I'd like to get an opinion or two from you specialists. Where do you think my problem lies? Would it do any good to disconnect the MAP, the MAF and other connectors and try to clean them?
I would be very appreciative of your time and suggestions.
So I decided to clean the PVC valve and change the air filter last month. No problem until a week ago when the check engine light came on. I assumed I had a thermostat problem since I have to drive the car about a mile before that light comes on. Then when I shut down for about 30 minutes for shopping, etc., the light will not reappear until I've driven another mile or so. The light will always be off when I start the car each day.
Last Saturday I stopped by DriversEdge for their opinion. The mechanic hooked up the code reader (which he said was PRE-OBD1) and it read 137. So we agreed to change the fuel filter and clean the fuel rail, the fuel injectors and the throttle body. But on Sunday the light came on again after a mile or so.
So before I go back to DriversEdge for phase two I'd like to get an opinion or two from you specialists. Where do you think my problem lies? Would it do any good to disconnect the MAP, the MAF and other connectors and try to clean them?
I would be very appreciative of your time and suggestions.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
From other indicators (spark plug condition, exhaust condition) would you agree with the DTC that that bank of cylinders is running rich?
By the book, one of the first checks when diagnosing an O2 sensor code is to check fuel pressure (though normally one would expect high fuel pressure to affect both banks, not just one). It only takes a few minutes to see if something is grossly out as far as fuel delivery goes.
What happens if you swap the left and right O2 sensors? If the DTC follows the sensor, then the sensor probably needs replaced. If the DTC stays on the same side of the engine, then the fault is probably elsewhere.
By the book, one of the first checks when diagnosing an O2 sensor code is to check fuel pressure (though normally one would expect high fuel pressure to affect both banks, not just one). It only takes a few minutes to see if something is grossly out as far as fuel delivery goes.
What happens if you swap the left and right O2 sensors? If the DTC follows the sensor, then the sensor probably needs replaced. If the DTC stays on the same side of the engine, then the fault is probably elsewhere.
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Ok, lets cut the crap. O2 sensors are maintenance items, and should be replaced every 60,000 miles on your vehicle. I'm sure they are well over that. Most O2 sensor codes are valid sensor codes and indicate the sensor has failed.
However, your code does not indicate a sensor failure, you code indicates that your engine is leaning out. (I still recommend replacing the sensor, at the same time do your plugs) It would do good to clean or replace the MAF sensor. You problem is most likely a major vacuum leak, or a bad fuel pump. Have you tested your fuel pressure?
PS, your vehicle only has one O2 sensor, so there is no way to distinguish whether one or both banks are being affected. The high NOX confirms you are leaning out.
However, your code does not indicate a sensor failure, you code indicates that your engine is leaning out. (I still recommend replacing the sensor, at the same time do your plugs) It would do good to clean or replace the MAF sensor. You problem is most likely a major vacuum leak, or a bad fuel pump. Have you tested your fuel pressure?
PS, your vehicle only has one O2 sensor, so there is no way to distinguish whether one or both banks are being affected. The high NOX confirms you are leaning out.
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
Thanks for the responses. I'll have some info when I visit DriversEdge. By the way Bear, this 93 has only 77,800 miles ( my wife got the new car last Christmas!! ). I changed the plugs and wires last year so I will rule that out. Is the O2 sensor something I could do? I couldn't do that job on an old 82 buick without major injury!
Thanks.
Thanks.
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
Bear,
Here's a new input that might be relevant. After I stopped yesterday (the light came on as usual after a mile or so), I shut down the motor for a second and then cranked up again. The light did NOT come on. Anything you can make of that?
Here's a new input that might be relevant. After I stopped yesterday (the light came on as usual after a mile or so), I shut down the motor for a second and then cranked up again. The light did NOT come on. Anything you can make of that?
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
Hello again,Recently cleaned the MAF but still have the CEL. Next item will be the O2 sensor. I'm told that this V6 has only one. Would appreciate if somone would tell me exactly its location. What should I expect to pay for a new one? Also tell me where the MAP sensor is located and if its something I can clean.The mechanic at DriversEdge told me that this Explorer model gives PRE-OBD1 codes, not OBD1. Where would I find a listing of such codes?Many Thanks
Trending Topics
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
Funny, I have a 92 and it is OBDI,
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
You can pursue the O2 sensor, it is due to be changed, however, if the sensor were bad and triggering that code, you vehicle would be running excessively rich. If the vehicle were running rich you would have extremely low NOX readings and elevated HC and CO readings. You have the opposite, which to me suggests that the fuel pump may not be keeping up. The fuel can't keep up, the vehicle leans out (may be accompanied by a pinging sound while accelerating) and the NOX reading goes up. Any kind of vacuum leak will also cause problems, though vacuum issues show up at low RPM and disappear as RPMs increase. Misfires can also trigger lean codes. If the intake tube has not been properly installed (i.e. the clamps are loose, or the breather tube is unhooked) then the MAF will not get good readings and a code can be set.
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
Thanks for the responses. I went back to the mechanic where initial investigations were done --- He's no longer there. So they read the code output and now there are two codes --- 137 and 538 (rich bank 2 they said). After an hour of fooling around DriversEdge gave up and suggested that I go to a Ford dealer for a complete diagnostic since Ford could pinpoint the problem with their older equipment that DEdge doesn't have. So I plan to do that provided the dealer has a very mature mechanic that knows his way around any year Explorer, especially old ones. BTW, I got under the car on the lift and found that there are TWO O2 sensors not just one. Also the new mechanic said the codes are OBD1 not PRE-OBD1 as the other mechanic told me.
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
That is correct, that code means that a rich condition is present on that bank. Possible culprits include:
Faulty injector(s)
ruptured fuel pressure regulator
excessive fuel pressure
faulty MAF sensor
Faulty injector(s)
ruptured fuel pressure regulator
excessive fuel pressure
faulty MAF sensor
Thread Starter
|
Freshman User
Joined: Nov 2005
Posts: 35
Likes: 0
From: Dallas TX
Bear, I really appreciate your help here. Looks loke the newer code 538 helped a bit. I'm definitely running rich proven by the MPG last fillup. Question: If the problem lies with the fuel regulator, why wouldn't both banks show up as too rich instead of one bank? And secondly, where would I find the code listing for OBD1? Many thanks.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
KOER 538 is almost always operator error during the KOER test -- they probably missed the cue for the "goose" test.
EEC-IV code lists of varying quality are all over the internet. If FTE will permit the link, I like the listing at www.troublecodes.net/Ford
EEC-IV code lists of varying quality are all over the internet. If FTE will permit the link, I like the listing at www.troublecodes.net/Ford
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
There are two self-tests your '93 can run KOEO (Key On, Engine Off) and KOER (Key On Engine Running). Setup is the same, it's simply a matter of whether the engine is running or not. "Goose" test (officially called dynamic response test) is part of the KOER test. Put "Ford EEC-IV self test" into your favorite search engine and you should find several web-sites describing these two tests.