On humid cool days 20-40 degree F. My 2.5 doesn't like to start. I've replaced the whole ignition system and egr valve. If it's really cold it will start like dream. Anyhow, it would not start this morning so I thought I'd try using a hairdryer set on high hot into the air cleaner housing where the plastic intake hose attaches. The car started and as normal. So now I carry a hair dryer and extention cord where ever I go.

Maybe you have a bad MAT sensor. It measures the air temperature coming in to the engine.

The 2.5 doesnt have a MAT, I thought it might be something like that too. It does have a mechanism to pull warmer air off the exhaust manifold. But I dont see how that would effect the start process. At this point I think it helps dehumidify the air or forces a little more air in to the engine. When it doesnt start, it wont even fire. Maybe the ecm sensor for cooolant is bad?

What year is your Fiero?

JazzMan

'84. It's my winter car. It makes the scarifice so the GT stays safe and clean.
It's almost dead and I might be getting something else for a winter car, which mean I get to part the old girl out. When It runs , it runs good, just start that seems to be the problem I have an extra coolant temp sensor at home I'll give that a try, I'm at work. I think it has evil spirts in the engine someplace.
nothing I do seems to fix the problem. Moisture is getting somewhere I think it shouldn't since if it's dry outside I don't get this problem.

Maybe your TB injector is getting gummed up in the cold/humidity?

quote Originally posted by Dslice: The 2.5 doesnt have a MAT

True, it doesn't. Fiero's, or at least my 88, has an IAT. Same thing, different name. Throws everyone off. Threw me off. It doesn't speak of it in the Chilton's manual, just like it doesn't tell you how to de-tentionize the belt tentioner (pain in @$$). The IAT is on the passenger side of the intake manifold.

In 88's, or any car with DIS, like 87's, the IAT/MAT tells the ECM the intake air temp, of course. What it does with this information, decides what ignition timing to use. In 84-86's, there's a distributor, so I don't know if you guys have it or not. I haven't touched a GM distributor car in 3 years. So for a simpler fix, try advancing the timing a few degrees, and this will not only give you some more power, about the same as a really small shot of NOS, but it will be tuned a bit more for that 20-40 deg range of air temp. One thing though when doing this, as a precaution, don't use 87 octane. The pre-ignition avoidance abilities of high octane fuel, which prevents detonation, will help avoid the combustion going off too soon, which won't be good for your already dying engine. Besides, the high octane fuel will help clean out some of the carbon in the engine, making it run better, about six tanks of Mobil or Texaco premium grade should be enough to clean a good deal of that carbon. Don't use alot of fuel injector/system cleaner, which removes carbon, but is bad for the fuel gauge sender unit in the tank, and is bad for the O2 sensor, because all of that carbon that's removed ends up on the sensor, and clogs it.

A little cheat, if you do have an IAT on your's, is to take a 3.3K (I think it's 3.3k) Ohm resistor, and put one lead in each hole of the connector for the IAT. This will advance the timing to about 8-10+ deg by telling the computer it's about 31-32 deg F in the intake manifold. Neat, huh? That's why MSD has a knob for the distributor ignition systems, but not the coil pack DIS ones, because all that's needed is a simple resistor, not a $200+ box with a remote knob.

A little tip if you do use nitrous, or any forced induction, NEVER advance your ignition. NEVER!!! Always retard the timing, NOT ADVANCE!!!

I have poor running in cold as well, but that's my fault. I have Denso Iridium plugs, which are meant for high heat, and I gapped them to .055, as I do for all GM motors with a stock gap of .060 (they just run better, better than new), and I have a 160 degree thermostat, and I also have heat reflective insulation around my fuel lines and the air intake "box" filter housing, so heat is at an all time low with my motor. It used to overheat quite a bit during the summer, or be at 220 often, but now, I'm at no higher than 170 during the summer, and sometimes I'm as low as 130!!! So don't do what I did.

Hope this helps. If I made any errors, sorry. The freezing cold in Iceland makes it hard to type, and the Artic Circle just plain makes me sleepy.

Go.."brrrr"...Na...aaaa....vy.
Sm..oo.oooo..th....sail..llll..llling

------------------
Nitrously yours,
Airman Michael C Casaceli
United States Navy

Will work for Race legal HKS boost controller and custom ECM.

My fiero doesnt chew gum. Actually that is a thought. I should run some injector cleaner through and see if that helps, thought it seems to be getting fuel. I can smell gas when I try to start it and it doesnt fire. In fact I sometimes unplug the pump fuse as I crank it to get it to fire. Which in the past has led me to belive it was a ignition problem. But a sticky injector might cause some flooding issues too I suppose.
Would a bad IAC or the Thermac thing is shot cause hard starting?

Oh, BTW,

I'd just like to mention to everyone, that I now have a T3/T4 hybrid turbo in my possesion, and it's going in my Fiero, on the custom 2.2 Ecotec motor I'm building.

Please, bow to me later. I'm freezing.

Go to www.fieroturbo.com.