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Discussion Starter · #1 ·
1995, 5 speed LX. 149K miles

I just recently had a new radiator put in, along with a freeze plug that was giving trouble and a manifold leak fixed/replaced. While this took care of most of my problems, the Check Engine light stays on (It was on before the work)

When I start up the car, the light is not on...but usually within 5 minutes or so it comes on. The shop tested it and said they could not find a problem and no reason for the light to come on, but there it is...

Only things wrong now are the AC does not work (does not seem to be low on freon) and the car seems sluggish. I plan to change the fuel filter and the air filter today...anything else to look into?

Thanks!
Rod
 

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Mine does exactly that.. mine needs a cam sensor.

I put a new one on with a new head a couple of years ago, but when I unplugged its connector it has some engine oil inside of it (with no leaks around the sensor) so I'm assuming the sensor itself has started leaking somehow.

Unfortunately, you have to unbolt the intake manifold to get this sucker out and back in, so I keep putting it off.

Of course, I can't be sure this is your problem as well...
 

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Discussion Starter · #5 ·
zzyzzx said:
How old is the O2 sensor?
As old as the car, about 15 years...

zzyzzx said:
When was the last time you cleaned the MAF?
I don't know what the MAF is...sorry, can you explain?

zzyzzx said:
Did you check for vacuum leaks? If so how?
No, I would not know how. There was a damaged/old vacuum hose that I replaced about a year ago, it was causing the car to stall.

zzyzzx said:
Did you check the PCV elbow?
I don't know what that is. Again, sorry, I am trying to figure all this out and I really don't understand too much. That is why I am asking.

Thanks,
Rod
 

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Discussion Starter · #6 ·
FordMan59 said:
The ECU should have one or more trouble codes stored if the check engine light is on. I'd suggest start by pulling the codes and getting them defined. That should help you resolve your check engine light problem.
I have seen the write up on this, and will have to ask some questions on it as I don't understand some parts of it. However, a local shop did the work on the car and they said they checked the codes and could find nothing wrong.

Thanks,
Rod
 

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OK FIRST OFF, are you SURE it's the check engine light? Sometimes another light can fool you. These are common for the coolant bottle float sticking and making a low coolant light come on, which I suppose could be confused with a check engine light. You can unplug the sensor at the filler neck of the plastic coolant bottle under the hood and if this is the case the light will stay off.

Assuming your mechanic is correct (I'm thinking not) and there are no codes but the check engine light is indeed on, then you've either got a short circuit in the instrument cluster or the wiring for the check engine light (not likely) or the computer itself is bad.

Diagnosing either of these conditions involves a lot of electrical testing and disassembly of the cluster, and quite frankly, I don't feel you have the skills, knowledge, or experience to do either.

Not to seem rude, but the top 3 discussed things on this board even remotely relating to your problems are the Positive Crankcase Ventilation (PCV) Valve/elbow (and vacuum leaks), the Mass Air Flow (MAF) sensor, and the Oxygen (O2) sensor. Since you don't even know what these are it's obvious that you've done almost no research on this board, as it would be nearly impossible to search for ANYTHING here without bringing up at least one of those items.

My advice? Get the opinion of another shop... or follow one of the multiple write ups here for pulling your trouble codes. It's possible the first shop had faulty equipment, inexperienced personnel, or just plain did not want to get involved in this. This wouldn't be the first time a shop lied to a potential customer (as a professional tech I see this sort of thing happen all the time at other shops).

You have to understand that most cars on the road today are OBDII and have been since 1996. What this means is that for the most part, one piece of equipment can scan virtually every car made since then, as they all share the same diagnostic connector and diagnostic "language" standards set by the US government. Many other countries have also followed suit. It's been almost 15 years now.

Since your car is a 1995, it is NOT OBDII and has a completely different connector, speaks a completely different language, and needs a scanner compatible with the older FORD diagnostic systems (EEC-IV to be exact). Many shops do not have this equipment anymore. If the equipment malfunctioned, then they probably didn't replace it. If the shop is newer than a few years old, then they probably never bought it in the first place.

It's possible your mechanic doesn't have this equipment and flat out lied to you to get you to go away. While there is a way to pull codes on these without a compatible scanner, a lot of younger mechanics don't know this procedure, nor do they care to learn. I'm kind of that way with carburetors. They were almost extinct when I started out in the business (in '94) and as a result I never bothered to care about tuning, tweaking, or rebuilding them.

If you do manage to pull trouble codes out of your computer, feel free to post them here. We'll be a lot more help at that time.

If you manage to verify for sure that no codes exist, then you're going to have to run some electrical tests to verify the check engine light circuit is not compromised, that the computer is getting the proper power in the proper places, and that the ground circuits of the computer are intact. This testing can get quite involved at times and some people feel it's easier to get a replacement used computer, plug it in and see, so of course that is an option as well.. but if there is a power/ground issue it could damage the replacement computer as well.

Past this, anything else we tell you is nothing more than a "guess", as there are hundreds upon hundreds of potential failures that can cause your symptoms. We've listed the more common ones but you don't know what these are so it's time for you to do some research on your end.
 

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Discussion Starter · #9 ·
HyBrad said:
OK FIRST OFF, are you SURE it's the check engine light? Sometimes another light can fool you. These are common for the coolant bottle float sticking and making a low coolant light come on, which I suppose could be confused with a check engine light. You can unplug the sensor at the filler neck of the plastic coolant bottle under the hood and if this is the case the light will stay off.
I am positive that it is the check engine light. The coolant light was coming on also, which is why I had the work done at the shop on the radiator and freeze plug.

HyBrad said:
Assuming your mechanic is correct (I'm thinking not) and there are no codes but the check engine light is indeed on, then you've either got a short circuit in the instrument cluster or the wiring for the check engine light (not likely) or the computer itself is bad.

Diagnosing either of these conditions involves a lot of electrical testing and disassembly of the cluster, and quite frankly, I don't feel you have the skills, knowledge, or experience to do either.
I would agree.

HyBrad said:
Not to seem rude, but the top 3 discussed things on this board even remotely relating to your problems are the Positive Crankcase Ventilation (PCV) Valve/elbow (and vacuum leaks), the Mass Air Flow (MAF) sensor, and the Oxygen (O2) sensor. Since you don't even know what these are it's obvious that you've done almost no research on this board, as it would be nearly impossible to search for ANYTHING here without bringing up at least one of those items.
Well, not actually true. I did searches and tried looking into the issue before posting. Not knowing a lot about the issues makes it harder to find the items you need. The O2 sensor I do know about and was planning to replace. It is only $50 or so and I can do that pretty easily.

I just find that if I don't understand a write up, it is better for me to ask.
Sorry if I seemed rude...I do try to find things out before I ask.

HyBrad said:
My advice? Get the opinion of another shop... or follow one of the multiple write ups here for pulling your trouble codes. It's possible the first shop had faulty equipment, inexperienced personnel, or just plain did not want to get involved in this. This wouldn't be the first time a shop lied to a potential customer (as a professional tech I see this sort of thing happen all the time at other shops).
Point taken.
HyBrad said:
You have to understand that most cars on the road today are OBDII and have been since 1996. What this means is that for the most part, one piece of equipment can scan virtually every car made since then, as they all share the same diagnostic connector and diagnostic "language" standards set by the US government. Many other countries have also followed suit. It's been almost 15 years now.

Since your car is a 1995, it is NOT OBDII and has a completely different connector, speaks a completely different language, and needs a scanner compatible with the older FORD diagnostic systems (EEC-IV to be exact). Many shops do not have this equipment anymore. If the equipment malfunctioned, then they probably didn't replace it. If the shop is newer than a few years old, then they probably never bought it in the first place.
I see that scanners for OBDI are available for about $20 or less. But I also see the write-ups that say the same thing can be done with a wire.

Do you think it is worth the $20 to get the scanner?

HyBrad said:
It's possible your mechanic doesn't have this equipment and flat out lied to you to get you to go away. While there is a way to pull codes on these without a compatible scanner, a lot of younger mechanics don't know this procedure, nor do they care to learn. I'm kind of that way with carburetors. They were almost extinct when I started out in the business (in '94) and as a result I never bothered to care about tuning, tweaking, or rebuilding them.

If you do manage to pull trouble codes out of your computer, feel free to post them here. We'll be a lot more help at that time.
I hope to work on that tonight, or by this weekend when I have time and will post the results then.

HyBrad said:
If you manage to verify for sure that no codes exist, then you're going to have to run some electrical tests to verify the check engine light circuit is not compromised, that the computer is getting the proper power in the proper places, and that the ground circuits of the computer are intact. This testing can get quite involved at times and some people feel it's easier to get a replacement used computer, plug it in and see, so of course that is an option as well.. but if there is a power/ground issue it could damage the replacement computer as well.
I will look up a price on that computer.

HyBrad said:
Past this, anything else we tell you is nothing more than a "guess", as there are hundreds upon hundreds of potential failures that can cause your symptoms. We've listed the more common ones but you don't know what these are so it's time for you to do some research on your end.
Ok, thank you for your response. One comment said that the O2 sensor is well past replacement...do you agree?

Thanks again, and sorry for being such a newb.

Rod
 

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Not to be dumb, but is the sensor connected at the cat? I've done work before around the radiator and had left it unplugged when putting things back. Since you said you had work done on the radiator, I thought maybe it was disconnected to get the wiring out of the way, maybe not getting reconnected afterward.
 

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Sparky34kv said:
Not to be dumb, but is the sensor connected at the cat? I've done work before around the radiator and had left it unplugged when putting things back. Since you said you had work done on the radiator, I thought maybe it was disconnected to get the wiring out of the way, maybe not getting reconnected afterward.
Good idea. May not even have to be disconnected. Could have just been bumped hard enough to jostle the plug and effect it's opperation. Been known to happen, MANY times. ;)
 

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rjkardo said:
Ok, thank you for your response. One comment said that the O2 sensor is well past replacement...do you agree?

Rod
I've had 02 sensors to last 200-250K miles before, but I think the recommended change interval is something like 60K. Most likely if it's a bad 02 sensor your gas mileage will be way down. A bad 02 sensor will usually cause a 20-30% drop in gas mileage.
 

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While a bad O2 sensor can cause it to run funny and a check engine light come on, it's all really a shot in the dark until you find out what codes are set.

The $20 scanners have an led that flashes out the codes.. doing nothing more than a paperclip would do (to make the check engine light flash out the code). A good scanner that will actually read the codes and display engine data will cost at least a couple hundred dollars... otherwise don't waste your money.
 
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