iv been getting pretty crappy gas mileage lately and on the end of my tips a black residue seems to be forming very quickly. is there a way to manually change this or doesn anyone know of the ways to change it. thank you

I am having the same problem, anyone know why?

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I once got a warning from a Police officer because he couldn't keep up with me around some twisties. the prerequisite for a warning instead of a ticket was that I must let him drive it back and forth the way we had come. Burned a quater tank of my gas!

Me Too! I finally got my V6 to run closed loop - bypassed the ECM temp sensor with a 440 ohm resistor. the temp sensor is open, reporting the temp is -40°F all the time, so the ECM would not close the loop. 440 ohms to ground makes it think the engine is at 160°F. I will replace the temp sensor asap.

Now it is running closed loop and after 20 miles I get a 45 code - ox sensor reports running rich (new ox sensor).

Here is a stupid fiero trick I discovered that I havent seen anyone mention. After you jumper the A and B terminals on the ECM to check the codes, start the car up. If the light blinks about 3 times a second it is running open loop (wait till it warms up first). If it is running closed loop it blinks once a second, and if it is rich the lamp is mostly on, and if its lean its mostly off.

Mine is on steady, ie, as rich as it can be.

I checked the TPS with a voltmeter as outlined on the online Fiero service guide. Next plan to check the map sensor and the MAT sensor the same way. That is how I found the bad temp sensor.

If that doesnt help then I need to start looking at the hard stuff, fuel pressure too high, something wrong with the evaporation canister, stuck injectors.

oh hey, I just thought of something. my car was sitting for 2 years before I bought it and there were several yellow jacket nests in the door hindges and behind the mirrors. I wonder if they are in the air inlet for the air cleaner too?

I suspect my cat is clogged, even though the car runs pretty well at speed. I dont know if that will make it run rich. My biggest sign of trouble right now is taking off from a stop the engine bogs down, sputters and backfires. But I also suspect my plugs are fouled from running open loop for 120+ miles.

I will let you guys know what the magic bullet is when I find it on my car.

quote Originally posted by Ken Wittlief: Me Too! I finally got my V6 to run closed loop - bypassed the ECM temp sensor with a 440 ohm resistor. the temp sensor is open, reporting the temp is -40°F all the time, so the ECM would not close the loop. 440 ohms to ground makes it think the engine is at 160°F. I will replace the temp sensor asap. Now it is running closed loop and after 20 miles I get a 45 code - ox sensor reports running rich (new ox sensor).

The ECM thinks you're at 160. In reality you're what? 195+ ?

You're being fed gas based on the 160. i.e., too much for 195!
Might be why you're getting the code 45.
You might want to tweek the resistor value a bit.
Just a thought.

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Raydar - aka Steve

88 T-top Formula
88 soon-to-be-V6 coupe

my dash gauge is reading about 160, but maybe your right.

I figured 160 is better than -40.

I plan on replacing the sensor asap. But I dont think 160 => 195 would make it run that rich. I think I still have another sensor out somewhere.

I noticed that mt temp guage will read around 160 too. But If after a long drive I will make a quick stop somewhere get back into my Fiero and when I put the key in and turn it to the on position, my temp gauge reads much higher. Go Figure.

I noticed that too, in fact that helped convince me the temp gauge is working properly.

The sender is right next to the thermostat on top of the motor. When the engine is running the heat is constantly pulled past it by the coolant. But when you stop the engine for a while the heat from the rest of the engine (heads mostly) saturates the whole block to an even temp, and the sensor goes up towards 200, maybe 210.

Or think of it this way. When the engine is running the block may be at 200 or 230, but the coolant is about 110 when it enters the block, and 160 when it leaves the block, so when you shut it off the little bit of coolant that is in the block reaches the block temp.

to put closure on my posts in this thread - I found the problem on my car. A mouse had chewed a hole where the MAP sensor connects to the fuel pressure regulator under the intake plenium (dead center under it).

I had to pull the plenium off to get to the end of the hose, and I noticed the egr tube was cracked at the first ripple from the top.

2" of new vacuum tube: $0.20
new gasket set: $22
Map gas and brazing rods: $10
Can of red spray paint for the plenium while it was off: $6

having a V6 fiero w/ no error codes, doesnt stumble, and doesnt run rich/ blow soot, or smell like an old Ford: $Priceless!

Looks like I'm a member of the running rich group. The previous owner had bypassed the original equipment temp gage - not sure why. He installed an aftermarket temp gage which seems to work just fine except I am now suspecting that he did not relay the signal back to the ECM. I suspect that I run open-loop all the time. If that is the case will the ECM ever report a code. I have never had the check engine light come on except when starting the car, so I know the bulb is good.

He also removed the thermostat and wired the fan to run full time. Along with pulling the vacuum line from the EGR solenoid. I hope I can get it all fixed by the time emission testing is required.

The ECM has a separate sensor that it uses for temp - the gauge on the dash has its own sender - so that is not the problem.

if your thermostat is completely out, and the fan is on all the time then your engine will always run cold - the theromostat is not only there to keep the car from running to hot - its there to keep the engine at a constant temp - ie 180° for a 180 stat - if the temp is below that it closes down some and restricts flow it the engine is warmer, if its above 180 it opens up all the way till the engine cools down.

running cold all the time will cause your car to run rich and you will have poor mileage.

the vacuum line pulled from the egr valve - is it just pulled off and left hanging?! at least it needs to be plugged - I would put it back on and get the egr system running correctly - the ECM expects the EGR system to all be there and to be working, and whenever you let off the gas it tries to open the EGR valve and it advanced the timing cause it knows its doing this.

If for whatever reason the EGR valve is not opening when the ECM tells it to, then your timeing will be wrong for what is flowing through the intake manifold and you will get surging, and pinging in your motor - not good!

Also if the vacuum line is pulled and leaking it will make other sensors, the MAP sensor for example, be off. Get a flashlite and a dental mirror and trace all the vacuum lines end to end till you can make sure none of them are disconnected or damaged. Also get a short piece of new vacuum line and pull the lines from the intake manifold, and try to suck on them with the new line attached till it sticks to your tongue - if it wont stick to your tongue, its leaking somewhere along its length.

Thanks Ken - that explains my confusion looking at the electrical schematics and seeing 2 different wiring diagrams for the temp sensor - there are two of them. Right now it doesn't take too long for the car to reach 160F, because it's starting out about 110F. Which reminds me, I need to get my AC fixed also - tough this time of year without one.

The vacuum line from the EGR solenoid is plugged with a screw. The disgram on the trunk lid shows it going no where, that is where mine goes. Where is it suppose to hook to? This is the single line from the ERG Solenoid, going foward toward the front of the car.

on my '85 V6 the line that goes forward is about 15" long and goes to a hardline across the firewall to another flexible one to the bottom of the air filter canister.

Im not sure what that lines function is, could be it only supplies fresh air to the solinoid when its open - might not be critical - not sure.