Check engine light

[IAmThor]

Hi, I have a '94 Explorer XLT with 113k miles on it and I can't figure out why my check engine light comes on when the engine goes over 2000 RPM for any amount of time. I have noticed a little oil leaking out of one of the gaskets, but there is no oil drop in the reservoir. Please help cuz I don't have a code reader for this generation of car. Any help would be greatly apreciated

 

[Jstcruz]

Go to Advance or Auto Zone to have the code read, write down the code/codes and post that on here. You will most likely get tons of help that way

 

[swshawaii]

http://www.explorerforum.com/forums/showthread.php?t=255962&highlight=trouble+codes

 

[marragtop]

Since it's a 94 you have OBDI and you need to find someone with the correct reader which is Ford specific. I'm not sure Autozone will have it. Here's the one you need: http://www.ebay.com/itm/Equus-Compu..._Automotive_Tools&hash=item5aeba0fe8d&vxp=mtr

 

[awood]

Or...you could read the sticky above and pull your own codes.

My 94 is currently doing the exact same thing. The code I pulled relates to the MAF sensor. As soon as I can make it to the auto parts store, I'm going to try a can of MAF sensor cleaner and see what happens.

An EGR valve also doesn't come into play until the engine is warm and above Idle. That could be an issue too. It's important to pull your codes so you know what you have, and don't spend money unnecessarily.

 

[IAmThor]

Well, the other day, I noticed that I have an exhaust leak in front of the o2 sensor is, so I'm thinking that's what it is. But I went to Advance and they said they couldn't pull codes on it

 

[arco777]

Well, the other day, I noticed that I have an exhaust leak in front of the o2 sensor is, so I'm thinking that's what it is. But I went to Advance and they said they couldn't pull codes on it

The link in post 3 shows how to pull codes yourself with a paperclip. It's pretty easy.

 

[IAmThor]

I'm doing that tonight so we'll see how that goes haha

 

[IAmThor]

The codes I got were: 549, 539, 72 and 66 dealing with the sensors and saying I had the ac/heat on when I did the test

 

[MrShorty]

Double check your interpretation of the flashes. I would expect an EEC-IV PCM to output either 3 digit or 2 digit codes, not both. Any chance the 72 is really a 172? The 66 a 336 or 136? Also, my code list doesn't show a 549, though it may not be the best code list.

 

[IAmThor]

I will check into that when I get the time. I've been really busy helping my girlfriend get her hospital bag packed (she's due next month) and helping my dad with the firewood. It's pretty hectic around here haha

 

[IAmThor]

Got the codes pulled finally

I finally got around to purchasing a, OBD-1 code reader and here are the codes I got. I understand like two of them so any help on how to fix the rest of the prblems would be greatly appreciated

KOEO (Key On, Engine Off)
33 - EGR valve not opening; Insufficient flow detected
72 - Insuficient MAF change during Dynamic Response Test
77 - WOT not sensed during Self Test
81 - Secondary Air Injection Diverter circuit failure
85 - Canister Purge cicuit failure
87 - Primary Fuel Pump circuit failure

KOER (Key On, Engine Running)
66 - MAF sensor circuit out of range (low)
35 - EGR valve Pressure Transducer/Position Sensor voltage out of range (high)
53 - Throttle position sensor out of range (high)
61 - Coolant Temperature sensor circuit grounded

Like I said, any help is greatly appreciated

 

[MrShorty]

Every good manual I've looked at says a '94 should be outputting 3 digit codes, not 2 digit codes (your first attempt had a mix of 3 and 2 digit, so I expect we should be seeing 3 digit codes). Even with the code reader, are you reasonably certain you are interpreting the pulses correctly? Any chance someone has put a '91 PCM into it?

If I assume these should be 3 digit codes, I would guess, for the KOEO results:

33x - EGR code of some kind whether KOEO or CM. Or, where you have not listed separate KOEO and CM codes, maybe this is the 111 pass code for the KOEO portion of the test, and the rest of the codes are CM codes.

172, 177, 181, 185, 187 are all O2 sensor codes/fuel control codes. A couple refer to the rear O2 sensor, a couple refer to the left O2 sensor, and couple are generic to both banks.

It is kind of hard to make specific diagnostic suggestions until we are reasonably sure we are reading the codes correctly.

 

[awood]

My 94 has 3 digit codes.
My 92 (RIP) had 3 digit codes.
I understand the 91's had 2 digit codes and the switch was made between 91 and 92.

 

[IAmThor]

I have to change the oil after I take my daughter back to her mom's house, so I will pull the codes again and see. It might be that the previous owner put a different year computer in it. I'll check her out and double check then triple check to make sure

***Edit: The code reader I have is an Actron CP9015 OBD1 code reader from Autozone for $29.99. I just reread the instruction book and I guess I misinterpreted it. It does not give a single flash/beep in between codes. This means that my codes are:

KOEO
133
172
176
181
186
189

KOER
165
138
153
161

 

[IAmThor]

I have to change the oil after I take my daughter back to her mom's house, so I will pull the codes again and see. It might be that the previous owner put a different year computer in it. I'll check her out and double check then triple check to make sure

***Edit: The code reader I have is an Actron CP9015 OBD1 code reader from Autozone for $29.99. I just reread the instruction book and I guess I misinterpreted it. It does not give a single flash/beep in between codes. This means that my codes are:

KOEO
133- N/A
172- Heated Oxygen Sensor indicates lean conditions, right side
176- Heated Oxygen Sensor indicates lean condition, left side
181- Adaptive fuel rich limit reached at part throttle, right side
186- Injector Pulse - width higher than expected
189- Adaptive fuel rich limit reached, left side

KOER
165- N/A
138- N/A
153- N/A
161- N/A

I think the ones that showed up N/A in my Haynes book, I read wrong, so I will check that out later today. Can you dumb down the KOEO codes for me? Am I going to have to replace the O2 sensors?

 

[MrShorty]

They are technically CM codes and not KOEO codes (if needed, doonze's post on pulling codes linked in post #3 and/or my notes on pulling EEC-IV codes thread where we explain how to distinguish KOEO from CM codes).

As noted, all of the CM codes are O2 sensor/fuel control related codes. Many people, especially if the O2 sensors are old enough to be questionable, will replace the two O2 sensors and see if that is the problem. If new O2 sensors do not fix it, then they will go through the more difficult task of diagnosing the codes with known good O2 sensors.

All of those codes are because the O2 sensors are indicating lean. From other symptoms, would you agree that the engine is running lean, or is the engine running rich? For example, is the exhaust a heavy black -- indicating rich? Are the spark plugs carbon fouled -- indicating rich? If the O2 sensor is indicating lean, but the engine is running rich, that would point to a problem with the O2 sensors/circuits. If the O2 sensor is indicating lean, and the engine is actually running lean, then the O2 sensors are probably doing their job correctly, and you need to determine why the engine is running lean.

By the book diagnostic instructions usually suggest checking fuel pressure as the first step in diagnosing O2 sensor codes.

 

[IAmThor]

It's a good thing you told me that because I was just going to buy new o2 sensors and see if that fixed it.

There is no black smoke coming out of the tail pipe, but I believe that I have an exhaust leak on the y-pipe and it sounds like my cat is rattling... Could just be a loose shield but I'm not checking till it warms up a bit. The leak in the y-pipe would cause them to read lean, right?

I do know that my lifters are ticking when I step on the gas, but I don't think that would have any effect on the fuel mixture, would it? Thanks for the heads up though. I will check out that thread again