'83 Mark VI runs rich for years, still can't fix. . . .

[onedollarbob]

Well, long time browser first time n00b. . . .

Anyway, always had Mark V's, in states w/out smogs, now in CA I have a Mark VI that is too beautiful to part with, so, instead of falling in love with a woman, I fall in love with the Lincoln.

Everything is stock as God intended. 125k old-fogey-driven miles. It has always run rich, which didn't matter to me as you don't drive an '83 Mark VI in today's world for gas mileage, but I'm going on the third inspection that won't pass, and I'm ready to just fix the thing. I managed to sort out all the other issues and now it's just the high CO2 that is failing inspection. O2, coolant, and MAP sensors check out. Fuel pressure is correct (39ish). Evap system is good. I don't do code readings (as a person that grew up with Mark V's wouldn't), so I can't speak for the ECU, though I changed it out with a "new" one (who knows anymore where they get the parts) with same results.

Anybody know how to get the 302 CFI to quit running rich under stock conditions, with all usual culprits checking normal? I am ready to blame the fuel injectors, though I replaced them 2 years ago.

[Mainemantom]

I hope your Lincoln does not get listed as a gross polluter. Last time I was in Ca. a gross polluter had to have more smog checks. There is a age where no more smog checks are required . Is yours old enough ? You might try having a pressurized cleaning done. It costs about $160 and cleans out the cats. I had one done to one of my lincolns a few years ago. I passed smog really clean after that.

[1990LTD]

do they have a throttle position sensor?

[Ike Clanton]

Pretty funny you want to fix the car but "don't do code readings."

[onedollarbob]

To Maine, Yes, I think I have been blacklisted as I have cheated the smog tests for 3 times running now. It used to be, "oil change," "20 minutes on the freeway on the hottest day of the year", and "remove air filter before pulling around the corner into smog station" and I would pass by 1 point. Now CA wants a real mechanic evalling and passing it, a.k.a, money to be made under the guise of "protecting the environment". Don't say cat converters--last thing I want to throw money at. But maybe, anyway, if I rule out injectors.

RE: the TPS, I am pretty sure this system has one--I am an armchair mechanic, though, and this is one detail that I haven't bothered with yet. The car does act funny if I soft pedal the gas around 35-ish, so maybe TPS is not out of the question if it exists on this car. Thanks for the lead.

[onedollarbob]

Pretty funny you want to fix the car but "don't do code readings."

Yes, it's a laugh riot. I basically dismiss the "code reading" on the 302 CFI. You can get just as much done by testing the sensors and systems the old-fashioned way. FWIW, I had a mechanic plug it into a reader and he got nothing. So there you go. Thanks for your handy tip.

[Mainemantom]

One thing I ALWAYS did is replace the oil, filter, air filter, cap,rotor, bosch plugs and wires. at least have a new set to exchange for the test. I always liked to take it on 1 hour trip before the test to get it hot. Up the mountain from Bakersfield to Tehachapi or the Grapevine did it. It is amazing what a little thing can do to make it fail.
Check TPS. Get the pressurized cleaning before replacing the cats !

[gadget73]

Its an EEC3 car. Code readings mean nothing for all intents and purposes. You can give it a shot, but I'd bet it will tell you fuck all thats useful. It wasnt till 84 when the computers got good enough to actually be worth scanning, and even thats dubious at times. Did it generate no error codes, no codes at all, or one of those " general fault" codes thats also totally useless? Fairly sure EEC3 has an "AOK" code but I dont know what it is.

Anyway, when you said the O2 sensor checks out, how did you check it? CFI cars tend to run a little fat, but they get really rich when that sensor goes bad. If it hasn't been replaced already, I'd really give that a shot. if its the same as an 84, the sensor is like 20 bucks. Most of the rest of the EEC3 sensors I know are not the same as 84+ parts, and are considerably more difficult to find and pay for. That MAP, last I checked, was some $250 and I think the TPS is also some stupid expensive number. The TPS you can ring out easy enough with a voltmeter. I think EEC3 runs 9 volts for reference, but one wire will be ground, one is hot, and the other is your moving contact. I do not know what the proper value is for an eec3 idle position but it ought to smoothly range from whatever value is idle up to nearly the reference voltage.

Another thought, whats your manifold vacuum run at? SHould be better than 17 inches if the system is going to work correctly. 83 would also have that crappy timing chain thats inclined to stretch and skip. You wouldn't likely notice it since the timing is crank trigger driven but if the chain is slopped out it probably won't help how the motor runs.

[Lincolnmania]

they run rich when the oxygen sensor is bad and also when the timing chain is sloppy

[onedollarbob]

I just replaced the timing chain as the cover gasket was leaking coolant and I figured, why not?, since I had all the stuff off. It was still the original, and definitely a bit slack--though not terrible. Nothing changed as far as the fuel mixture readings, though.

Re: O2 sensor, well, I got voltage, wires are like new, and the voltmeter fluctuated as expected. I didn't test beyond that, and it does appear to be the original, so maybe worth $20 for a new one to just rule it out.

The TPS turns out to be $40 and not hard to r/i, so probably will do that "and see".

The code readings are non existant. Nothing. Not even the 11 for "AOK". Even the mechanic I tried got nothing. And he actually knew about the vacuum pump on the BMAP sensor and test light setup. This is why I tried swapping out a new ECU (same results), and why I am affirmed in ignoring code diagnostics on a medieval system like EEC3.

People talk a lot of crap about EEC3, but it is durable and simple, if not the worst of compromises in the early days of fuel economy. Properly tuned, EEC3 on a 302 is a lovely purr and smooth ride, not quite like anything else.

[onedollarbob]

All the sensors checked out. I double checked them. Fuel injectors and fuel pressure checked out. I was getting crazy frustrated with this.

In the meantime, I took the new ecu back that I had first swapped, since it didn't make any difference and wasn't delivering codes, and wouldn't you know but I figured out the original ecu that was on my car was the wrong part all along for my vehicle. I guess just because you match the PN from your vehicle's part does not mean you are getting the right part!

I exchanged for the correct PN and no more rich mixture. Not sure how it even ran with the wrong ecu on it all these years. Between that and timing chain, the vehicle idles, runs, and accelerates like velvet now. I can't believe I had gotten used to just how truly crappy the car was driving before this. Best part is I passed smog this morning.

[MattsLincoln]

All the sensors checked out. I double checked them. Fuel injectors and fuel pressure checked out. I was getting crazy frustrated with this.

In the meantime, I took the new ecu back that I had first swapped, since it didn't make any difference and wasn't delivering codes, and wouldn't you know but I figured out the original ecu that was on my car was the wrong part all along for my vehicle. I guess just because you match the PN from your vehicle's part does not mean you are getting the right part!

I exchanged for the correct PN and no more rich mixture. Not sure how it even ran with the wrong ecu on it all these years. Between that and timing chain, the vehicle idles, runs, and accelerates like velvet now. I can't believe I had gotten used to just how truly crappy the car was driving before this. Best part is I passed smog this morning.

if you need any eec iii map sensors i have three here that work that im selling for $20 each.

[gadget73]

All the sensors checked out. I double checked them. Fuel injectors and fuel pressure checked out. I was getting crazy frustrated with this.

In the meantime, I took the new ecu back that I had first swapped, since it didn't make any difference and wasn't delivering codes, and wouldn't you know but I figured out the original ecu that was on my car was the wrong part all along for my vehicle. I guess just because you match the PN from your vehicle's part does not mean you are getting the right part!

I exchanged for the correct PN and no more rich mixture. Not sure how it even ran with the wrong ecu on it all these years. Between that and timing chain, the vehicle idles, runs, and accelerates like velvet now. I can't believe I had gotten used to just how truly crappy the car was driving before this. Best part is I passed smog this morning.

Interesting. I wonder what the ECU you had was originally for and why it was changed initially. Either way, cool that you got it running right. EEC3 does run well when its running well, but so few people know anything about it that its shunned as some sort of vast evil. Fuel injection in general gets that sort of rap, but the simple truth is, its a lot harder to fix if you don't know how its supposed to work in the first place.

[sly]

its a lot harder to fix if you don't know how its supposed to work in the first place.

this is so true about ... umm... everything

[1987cp]

Wait a minute. High CO2? Sure you don't mean CO? CO is a pollutant, CO2 isn't.