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Discussion Starter · #1 ·
Anyone have any ideas on this problem I am having? 95 Sable, 3.0, 295,000 miles on it. Check engine light comes on but never sets a code. Have driven it with the scanner hooked up and the light comes on but no code. Think I have issolated it to the fuel system. If I leave the gas cap tight the light will come on and the car will run like it is missing 3 cylinders. If I loosen the cap while it is doing this the car will start to smooth out but the light will remain on sometimes. As long as the cap is loose the car runs good but the light will come of and on, particuarly if driving up hill with a load on it. I saw a post on here suggesting that the T fitting under the radiator could be of an issue since I do smell fuel fumes from time to time. The fitting was clean but I did try to blow air through the vapor line that runs to the tank. There is not any air coming out of the tank but the air is coming out of a small vent hose that is running with the fuel and vapor line near the fuel filter. Should air be coming from the tank and not this vent line? Any ideas or suggestions would be greatly appreciated.
 

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Your gas cap may not be venting, a simple $5 try would be to buy a replacement cap and see if that fixes the problem. Leaving the cap loose and that fixing the problem tends to suggest that to me.
 

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This may be a dumb question, but are you running the complete code test, including the CM part of the KOEO test? When you say "no codes" do you mean no code output or you get a pass (111) code?
 

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Discussion Starter · #5 ·
Yes I am getting code 111. No other codes are present at all including the CM part of the scan.
 

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Discussion Starter · #6 ·
And once it gets hot and sets for about 5 minutes it will not start again until the car has cooled back down, maybe an hour or so.
 

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^^^^ +1

Classic EEC IV TFI and/or PIP failing symptoms. SOmetimes TFI/PIP set CM codes when failing, but quite often, they dont.
 

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Discussion Starter · #9 ·
Thank you for the advice. I will dig into these next. Is there a method to testing either one of them?
 

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Discussion Starter · #11 ·
I replaced the altenator because I found the voltage was dropping off to about 12.3 when it got hot. That cleaned up many of the issues but I am still having an issue. I am now able to get codes. I am getting 172 and 176. The car will basically slow itself down to a dead stop and you can here it popping through the exhaust. When I loosened the gas cap I was able to get the car to go again. After replacing the altenator I did hear air escape from the cap for the first time since my issue started. Any suggestions?
 

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Gas cap isnt venting properly creating a vacuum in the tank and the pump cant pump againts the vacuum. Try going for a long drive with loose cap. If it runs OK, replace gas cap. I got bit in the a** by this same problem about 20 years ago on another Ford.
 

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Discussion Starter · #13 ·
I found 2 big vacuum lines with holes in them. fixed them. Now I have codes 176, 181 and 186
 

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172: HEGO sensor circuit indicates system lean (right side)
176: HEGO sensor circuit indicates system lean (left side)
181: Right side still lean, at richest adaptive limit, during part throttle.
186: Injector pulse width longer than expected

So basically it's trying to find a balance and it can't... I don't think both oxygen sensors are bad (stuck lean)... I'm thinking your head towards a new mass airflow sensor or a vacuum leak... The mass airflow sensor is higher on the totem pole then the oxygen sensors... In fact, your car doesn't use oxygen sensors until it warms up... (closed loop operation) when you've got a problem common to both banks you have to look at what parts are common to both banks...make sure the main air tube is tight, Before changing the Mass Airflow Sensor you could try cleaning it with Mass Airflow Sensor cleaner... Also consider, vacuum leaks can also cause this problem... ANY unmetered air will throw off the balance...

How does it idle? at what rpm? did you disconnect the battery to reset the parameters after repairing the hoses?
 

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Discussion Starter · #15 ·
I did clean the MAF. I am going to look for further vacuum leaks. I did not see anymore but I will keep looking. The car idles great at about 800 RPM and after fixing the 2 leaks I found I took it for a short drive and it ran as if there were no issues, with the gas cap tight but the light kept coming off and on. I dropped power to the ECM last night and will hook it back up this morning and take it for an extended drive. Would it take time for the ECM to re-learn the fuel curve since it has been driven so much running lean?
 

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Discussion Starter · #16 ·
I drove it again yesterday, about 30 miles. Same problem. Car runs good, check engine light comes on, car looses all power and sounds like it is running on 3 cylinders. Loosen the gas cap and the car smooths out and power is restored. Tried a new gas cap again with the exact same results. Codes 172, 176 and 186. Car also used about 1/8 of a tank of gas in that 30 mile trip.
 

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I agree it sounds like the gas cap isn't properly venting the tank, are you replacing the gas cap with the specified Ford/Motorcraft part????

If so, are you certain the aperature in the vapor recovery "T" is still in place & that it's size hasn't been messed with & opened up, as that can cause too much vacuum to be applied to the tank????

Are you certain the vapor recovery solenoid isn't stuck open????

Has the fuel filter been replaced lately & have you checked KOEO & KOER fuel pressure at the fuel rail schrader valve test port????

Are you certain the PCV valve isn't stuck open, that it fits snug into it's valve cover fitting & that it's rubber hose isn't dryrotted, split, cracked, or otherwise loose fitting, or damaged, as that can allow an unmetered vacuum leak that'll affect both cyl banks????

Did you use a plastic safe, non-residual product, formulated just for cleaning the MAF sensor, as has been suggested???? Didn't clean it while it was still hot, or poked it's elements with the spray straw & kept the MAF sensor squeeky clean upon re-installation??? Any damage to, or residue on the heated MAF sensor elements, can bake on & corrupt it's electrical PID output to the computer, about true air flow into the engine & that can cause the computer to mess up the fuel injector on pulse width & cause a skewed air fuel ratio!!!!

Is the electrical systems voltage in spec now???? If so, does the MAF sensor have full B+ to it's VPWR harness connection at KOEO????

You can check the MAF sensors output with your DVM.
At KOER, when you back probe the MAF sensor Signal & Signal Return connections, at idle, it should read between 0.2-1.5 volts & rise to about 2.0 volts at say 2K or so rpm, at any rate the voltage should rise at higher rpm. If it's voltage doesn't rise, or fall within those parameters, suspect the MAF sensor, it's wiring, or the B+ feed to it, or it's signal return to the computer is corrupt for some reason.

More thoughts for consideration, keep us posted on your trouble shoot.
 

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Discussion Starter · #18 ·
I did install a Motorcraft cap and that did not work. I am going to check the solenoid in the morning. I used CRC electrical contact cleaner on the MAF when I cleaned it. I have 14.12 volts when hot now. I drove it today for about 50 miles with the gas cap loose. Ran great with no issues, but the light came on off and on. Did not alarm me as it was running good. I could not get a read on gas mileage though. Got codes 181, 186, 189. Will be checking fuel pressure as soon as I get by to purchase one. The vent T is good and the restrictor is still in place. I am going to also pull the canister out and inspect it for any cracks too. Visually I can not find any other vacuum leaks. If I ever solve it I will post the find as I think it is going to be a really weird resolution.
 

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Discussion Starter · #19 ·
I tried to work with the canister purge solenoid yesterday. I replaces all the lines around it and checked on more time to make sure the T with restrictor was still in good condition. I read that if you turn the key on you should feel the solenoid click, which I did not. So I removed it and applied a direct 12 volts to it and it did open and appears to be working. I also noticed that if I applied vacuum to one side it would hold, vacuum to the other side it would leak. I reinstalled it in the car so that at idle there would be no vacuum passing through it. I assume it must open upon some signal from the comuter, but I was never able to get it to open while I changed the RPM range sitting in the garage. I am not sure that it is getting the proper signal. Any ideas or is there another method to testing this?
 

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Good trouble shooting on the apparent non operation of the purge solenoid.

Check the purge solenoids electrical connectors pins/sockets for corrosion, seeing as how it's close to the battery & water spray from the wheels, faulty wire crimp, bent pins, spread sockets, damaged wire or insulation.

Back probe the purge solenoid, at KOER on start up, it should have operating voltage to it.

If not, go to the computers firewall electrical connector & back probe for operating voltage there at start up. If you have voltage there, you have a wire run problem to the purge solenoid, so do some wiggle tests & see if you can find the faulty area. No voltage there suggests a problem at the firewall connector, wiring from the connector to the computer, or a connection, or switching problem in the computer, so maybe try some thump or wiggle tests to see if it'll wake up.
Connector pins/sockets & their wire crimps are good suspects & anywhere a wire bends, or lays on something thats hot, & or vibrates, or is exposed to water, are good suspect problem spots to check.

Keep us posted on your findings.
 
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