Intermittent CEL, crappy gas mileage

[sney]

So, the '91 Grand Marq LS I'm currently taking care of came with a few little issues.

First off, the Check Engine Light comes on every day. Usually it's when I'm accelerating and right before a downshift, but sometimes it'll just come on when it feels like it. Sitting at stoplights, idling down a hill, you name it.

Second, the gas mileage is just terrible. I think the gas tank on this baby is 16 gallons or so judging from the fill ups, but I'm doing 1/3 to 1/2 a tank every 2 days without going very far and that's just excessive. There's also a noticeable fuel smell in the exhaust.

Now I don't have to be a genius to know from those first 2 that I'm running rich, so I'm probably going to take a trip down to the Pick'n'Pull either today or tomorrow morning to grab a few O2 sensors. However, I don't know if I might need anything else, and I don't want to install some "new" O2 sensors only to have them fall victim to whatever ruined the old ones. (For all I know it's old age, but this is my first Panther so I'm looking at everything.)

The third issue that's been bugging me is what sounds like a belt rubbing. It used to go for a couple seconds and stop, but lately it's been going for much longer and I'm starting to worry that something is going to snap. I haven't been able to find it, since when I open the hood the sound goes away, but it sounds like it's coming from the driver side somewhere.

Fourth is that the tuner in the radio seems to be shot as I'll be driving along listening to the news and it'll just cut out and go to static, but the only question there is what other radios are compatible without having to DIY a wiring harness. And not really a priority. (And probably in the wrong forum section, but I figured I'd put everything in one post just so I can refer to it from time to time.)

Any and all suggestions are welcome.

[rick99601]

id say start with a basic tune up.

[sney]

err, at the risk of sounding like a moron, what would that entail? I was under the impression that a 'tune-up' was something you did with a carbureted car, and no longer done with the advent of electronic fuel injection. Or do you mean check and replace fluids? that's been done on schedule..

[86VickyLX]

Plugs, wires, cap and rotor, oil change with oil filter, air filter, fuel filter, replace the O2 sensors if they're old.

What codes are you getting?

[rick99601]

plugs, wires, distributor cap and rotor, fuel filter, pcv valve and screen. your front end also needs to be greased periodically.

these are the last of the cars that require any amount of TLC.

[rick99601]

jinx!

[ford man]

spark plugs, distributer cap and rotor and air filter would be a good place to start. Check and clean the egr would be worth doing and easy to do on that year.
Replace the fuel filter too. Check your timing with a timing gun after the new plugs... I would go for new o2 sensors if your going to do it...

How many miles are on her?

[ford man]

So many helpy helpertons ha ha

[1990LTD]

Two other sensors that could be screwing with your mileage: air charge temperature sensor, and engine coolant temperature sensor.


The ACT is behind the distributor, on the right side of the lower intake manifold. NOT the one with 1 wire, this one has multiple wire running to it.

The ECT is on the other side of the lower intake manifold, in the water neck I think. I can't visualize this one but it's not too hard to find.


a complete tune up

fuel filter
oil change and filter
air filter
distributor cap/rotor
spark plugs/wires
pcv valve/grommet/screen


most of the front end of these cars can be greased...inner/outer tie rods on both sides, pitman arm, upper and lower ball joints on both sides, and sometimes your universal joints will have grease nipples on them. there's a u joint at the front and rear of the driveshaft.

[1990LTD]

a throttle position sensor gone bad can also give you an intermittent CEL, usually accompanied with funky idle and near-stalling. usually.

[86VickyLX]

Two other sensors that could be screwing with your mileage: air charge temperature sensor, and engine coolant temperature sensor.


The ACT is behind the distributor, on the right side of the lower intake manifold. NOT the one with 1 wire, this one has multiple wire running to it.

The ECT is on the other side of the lower intake manifold, in the water neck I think. I can't visualize this one but it's not too hard to find.


a complete tune up

fuel filter
oil change and filter
air filter
distributor cap/rotor
spark plugs/wires
pcv valve/grommet/screen

If you don't have any starting problems, I wouldn't be suspect of the ECT or the ACT.
Check it for codes first.
ENGINE MUST BE AT OPERATING TEMPERATURE BEFORE PERFORMING KOER TESTS!!!!
Ground the little gray pigtail in the self test connector. The Self Test Input (STI)

Put your key on but don't turn the engine on just yet. It'll do some preliminary checks, and flash codes via the check engine light for key on engine off codes (KOEO)(apparent problems found by the computer during the self test). After it flashes those codes, then it will proceed to flash codes pertaining to memory. (Stuff that happened in the past). Should flash code 11 (system pass) Any other codes indicate a problem...

(KOER)
After you got those codes, start it up, when the check engine light flashes 4 times, step on the brake, and turn the wheel to the left 180* and then right 180* then just sit and wait as it continues the self test. When it's ready to flash codes, the idle will go back down, and then count the flashes, just as you did before. If it's warmed up, you should get code 11, (system pass) Any other codes indicate a problem.

I'll bet you'll get code 44, and 94. Which are the thermactor inoperative codes (If all the smog stuff is still attached, you got bad O2 sensors most likely)
Then there's probably either 31, or 33 which are EGR codes. If you get code 31, check the wiring for the sensor on the EGR valve, if in good shape, replace the EGR position sensor (EVP). If you get code 33, check to make sure the green plastic line is in good shape and not cracked, also check the red line that the green one goes into. If they are in good shape, clean the EGR valve, if you still have this problem, replace the EGR valve...

[sney]

I just went out there to read the (KOEO) codes, so many new replies!

my code blinks didn't really match the pattern listed on that ford fuel injection page, but I wrote them down as they were given to me.

First go around I got 21, 24, and 79, then again, 21, 24, 79.
79 was A/C or Defrost on during Self-test and that was true because the switch is loose and I don't like to move it anymore than I have to.
Turned off the defrost and got: 21, 24, 31. 21, 24, 31.

21) ECT out of self-test range
24) ACT or VAT input out of self-test range
31) EVP or PFE circuit below minimum Voltage

Is out of self-test range EEC-speak for "broken?" If so it's probably good that I haven't bought those o2 sensors yet.

We just rolled over 200,000 km (Canadian car) a couple months ago, and oil change/filter and air filter were done then, as well as checking levels and colours on the rest of the fluids. It's at about 204,500km now. (That's about 127,000 miles.)

I don't have any squeaky wheezy noises coming from the front of the car (well, except the driver door on a cold day) so I wouldn't have thought of greasing the steering and suspension, though I do have a grease gun so I suppose it couldn't hurt.

[86VickyLX]

I just went out there to read the codes, so many new replies!

my code blinks didn't really match the pattern listed on that ford fuel injection page, but I wrote them down as they were given to me.

First go around I got 21, 24, and 79, then again, 21, 24, 79.
79 was A/C or Defrost on during Self-test and that was true because the switch is loose and I don't like to move it anymore than I have to.
Turned off the defrost and got: 21, 24, 31. 21, 24, 31.

21) ECT out of self-test range
24) ACT or VAT input out of self-test range
31) EVP or PFE circuit below minimum Voltage


Is out of self-test range EEC-speak for "broken?" If so it's probably good that I haven't bought those o2 sensors yet.

We just rolled over 200,000 km (Canadian car) a couple months ago, and oil change/filter and air filter were done then, as well as checking levels and colours on the rest of the fluids. It's at about 204,500km now. (That's about 127,000 miles.)

I don't have any squeaky wheezy noises coming from the front of the car (well, except the driver door on a cold day) so I wouldn't have thought of greasing the steering and suspension, though I do have a grease gun so I suppose it couldn't hurt.

Check the wiring at the 3 sensors,

You made sure that the car was warmed up properly before you pulled codes right?
If you didn't, make sure it's warmed up and then pull the codes again.
If you still get the codes, replace the 3 sensors. ACT is on the drivers side, on the lower intake, next to #5 or 6 fuel injector, 2 wires.
ECT is on the passengers side of the lower intake, in a black pipe, 2 wires coming out of it.
EVP is on the EGR valve, on the upper intake, between the throttle body and the actual upper intake. 3 wires.

[sney]

That was for the KOEO codes, I haven't done the ER ones yet. Does it need to be warmed up regardless?

[gadget73]

honestly I would not bother with used O2 sensors. They start to degrade after about 60k, and they're enough of a pain in the ass to remove that its not worth pulling used ones and re-installing them. New ones aren't terribly expensive, I think the last ones I bought were about 35 bucks. Its cheaper if you get the generics and just splice your plugs in.