Hey all, so I bought a 1984 Fiero 2M4 for 1000 bones a couple days ago. It's black, has 77k original miles, the 2.5 L4 and the MY8 Economy Transmission. And so far, I love it! It's a blast to drive.
That being said, I do have a couple of issues/concerns.
First off: I had it running and was driving it around just a bit for about a half hour today, and the temp gauge barely moved, if at all. I took a look at the thermostat and it looked fairly new, but there's no way for me to know for sure. It wasn't super cold today, about 49 degrees F when I was out running it. Idle stayed at a constant ~1000 rpm after running for 5-10 minutes.
Second concern: When I first start it, it idles at ~2500 rpm for a minute or two, then goes down to ~1600 rpm, then finally ~1000 rpm where it stays, I'm assuming that means it is at operating temperature, though my gauge doesn't reflect that. My concern here is that I'm wondering if those are normal RPMs for a cold start/do you guys have similar RPMs?
Third Issue: The check engine light came on for about 5 seconds after running for a minute or two, and then again when I started driving, my first turn was onto a fairly steep hill where it popped on again, but only for maybe 5 seconds again. I plan on jumping the little harness thing in the center console tonight to see what codes it spits out.
Other than those things it's a solid vehicle, and I plan on storing it for the rest of the winter and using it as a daily in the summer, can't wait to see what kind of MPG I can get out of that transmission. Please post questions or comments, and thanks for your help in advance!
It's possible that the temp senders in your engine are not accurate. There is one for the computer and another for the gauge. Also, if your thermostat does not close completely it would take a long time to get the temp. right. If you get to around 900 rpm for the idle things are eventually working right....not sure why the cold idle should be that high, it may be an 84 Duke thing.
edit: I'm interested in your mileage also. The original EPA combined average mileage was 27, but I bet you can do a lot better than that.
[This message has been edited by Gall757 (edited 11-17-2013).]
The temp gauge is not necesaarily accurate. My 87 and 88 GTs gauge both run at the first notch most of the time, but does go up higher when I get into traffic after driving at highway speed. MY 88 Archie V8 the gauge reads about 20 or more degrees higher on its aftermarket gauge. Once you have the codes, if any, will tell you something. Once the engine is warm, mine idle at 900-1000 rpm.
Alright, cool, thanks for the replies guys. And am I correct to assume that the ALDL is under where I would rest my arm on the center console? By the cigarette lighter?
Edit: Gall, I remember reading on another Fiero forum that the Mileage for this transmission was supposedly 27 City and 40 Highway, was that misinterpreted by whoever posted it? I haven't looked at the EPA listings for it yet.
[This message has been edited by MustangFX93 (edited 11-17-2013).]
In 1984, the mileage rating for the MY8 and the M19 were almost the same...( ! )...and since that time they have changed the ratings method twice I think....so you see all sorts of numbers. You have to assume the two entries for the 4 speed are the 2 different transmissions.
Oh, you know what, I just found where I read 40 mpg, on Wikipedia! Under the history section for Pontiac Fiero.
"To this end, the Fiero was re-designed to use a fuel efficient version of GM's 2.5 L four-cylinder "Iron Duke" engine capable of 27 mpg-US (8.7 L/100 km; 32 mpg-imp) in the city and 40 mpg-US (5.9 L/100 km; 48 mpg-imp) on the highway with the economy-ratio transmission option. These figures are U.S. Environmental Protection Agency test-circuit results, published by Pontiac, and confirmed from multiple sources.[2] It was impressive mileage for a 2.5 L engine of the period, and still good by today's standards, but the three-speed automatic reduced highway mileage to only 32 mpg-US (7.4 L/100 km; 38 mpg-imp). With respect to fuel economy, the Fiero was intended to appeal to a market niche for which the Corvette with its V8 engine was unsuitable."
Interesting..well, I guess I'll just have to find out for myself, though I guess I won't be surprised if it doesn't get 40 highway, it's almost 30 years old, after all.
Interesting..well, I guess I'll just have to find out for myself, though I guess I won't be surprised if it doesn't get 40 highway, it's almost 30 years old, after all.
I'll be the first to guarantee that you will not get 40 mpg... unless you're continually going downhill with a tail wind. Be satisfied if you get close to 30 mpg on the highway with that old duke.
First off: Congrats on it staying too cool rather than too warm....much better this way. I agree with the others, potentially a bad gauge, potentially a bad sensor. Grab an IR thermometer and check the thermostat housing once it is "up to temp" and see if it matches the gauge...that will at least determine whether it is a real issue or an indicated issue.
Second concern: That is pretty normal for an 84. Mine does the exact same thing. Although I hear many say it is still high at the start...as long as it does come down to the 1000, I don't consider it to be an issue. Pick your fights...this one isn't worth it.
Third Issue: Not even going to guess on this one without knowing what codes it is throwing. https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes will help you determine the codes. Yes, the ALDL is behind the trim piece beside the cigarette lighter.
I have had three 84 Fieros with the three different trannies... I have seen high 40s in a duke/my8...but that is pure expressway driving on flat land (edit to add...I will also admit that 3.1 gallons for 150 miles isn't really sufficient to determine mileage) . Normally pulled around 30 with mixed driving. I used to pull about 29 mixed driving with the M19 I currently pull about 26 mixed driving with the auto. If I end up with another...it will be an M19. By far the most fun.
[This message has been edited by CowsPatoot (edited 11-18-2013).]
An easy-check on the gauge is to just turn the ignition on without starting. If the car's sitting inside a garage, the gauge should move to around the 100 degree mark. It may be a little lower if it's been sitting out in the cold Michigan weather. If it doesn't, the needle on the gauge has slipped. If it does move to the 100 mark, then look to the sending unit next. It's located on the head near the thermostat housing. It will have a round head with a slit in the side.
With careful right foot control, you can get great highway mileage with the econo transmission. I can get 30+ on my 87 GT. At 70 mph and 2400 rpm, the car does great. The last time I drove a coupe with a 5 speed, I had to down shift out of fifth gear below 55 mph.
My 84 SE Iron Duke Idles that high also, on a cold start. The check engine light going up a hill might be the MAP sensor. Mine did that when I first got it. My small hose that goes to the MAP sensor had a crack and going up hill made the engine work harder which would cause the hose to open up and that would set a code. My engine performance instructor helped me diagnose that.
[This message has been edited by FieroJosh1993 (edited 11-18-2013).]
A nice "mod" to the Fiero is to change the coolant temp sensor to the 3-wire version and move the wire from the temp sensor on the head to the coolant sensor. The head sensor will report about 25 degrees cooler than the coolant sensor... I've never had a 4-cyl so I don't know if they do that by default but on the V6, the gauge is run by a sensor on the head...
Thanks for the info, gents! So I checked my trouble codes just now. It popped out 13 and 44(lean), both having to do with the oxygen sensor. The engine doesn't run rough, but I can kind of feel that it isn't quite running how it should be. I'm assuming since both codes are the oxygen sensor, that it probably needs to be replaced. Anyone have any different opinions?
Edit: Also, what would be some symptoms of a lean exhaust?
[This message has been edited by MustangFX93 (edited 11-19-2013).]
When you get or order your new Oh2 sensor, I recommend getting one with the harness end attached from the factory. Many of them now come with just a pig tail and you must cut off your old harness plug and solder it onto the new sensor. I just don't trust that soldering doesn't affect the resistance through the wire.
Though a lean exhaust is a symptom caused by other problems, a sub-symptom of a lean exhaust could be a glowing exhaust manifold.
[This message has been edited by fierofool (edited 11-19-2013).]
Alright, I took a look at the O2 sensors on Rockauto and it looks like there are a couple that come with the plug attatched. I'll probably go with either Bosch or Denso brand. I've gotta make a 400 mile trip back home from the U.P. with this thing, you think it's alright to drive it with a bad O2 sensor? I assume the MPG will be pretty bad, but I won't have another chance to get it home before the snow REALLY falls.
If it doesn't warm up the thermostat may be in upside down. When you open the cap to look at the thermostat you shouldn't see the thermostat, you should see only the "handle." It's a thin piece of metal. When you pull it out, the thermostat will be at the bottom, about three inches down. If it's in upside down the coolant is just running through the handle and the thermostat is sitting up in the neck doing nothing, as if you didn't have one. Getting it in right side up may be a bit of a struggle. It's recommended that you clean the groove it is supposed to sit in with a rag. I didn't do that. It took a while to get it in far enough to get the cap back on. As soon as I did though, the temp gauge started working. And the heat, too.
The small tank and rusty senders make Fiero's hard to check the mileage on. I get from about eighteen to thirty something, depending on when the gas pump shuts off. I've kept track of every fillup. On average it's about twenty mixed and twenty-five mostly highway. 85 GT, four speed, 2.8.
I pulled out the thermostat(it was in the right way), and it made a satisfying "thunk" noise as it popped out of the grove it sits in, and I made sure to feel it pop back into it's little groove. So the thermostat is seated properly for sure, and isn't stuck open. I guess we'll just have to see how she takes to the open road after not having been driven for a while. I'm not too worried though, it's got pretty low mileage(77k) and was told it was well maintained by an older couple. Thanks for your help everybody, I'll let ya know the outcome of my roadtrip.
Be satisfied if you get close to 30 mpg on the highway with that old duke.
