Car does not like to run in cold weather.

[Tim]

My '89 2.5 Turbo Spirit (5 speed) has a problem I noticed a few months ago. Any time the air temperature was above 45-50 degrees, it ran fine. On cold mornings below 45 or so degrees, it'd sneeze, cough, sputter, and fart erratically until it got warmed up. It seems like a random miss dropping cylinders, if I had to guess, I'd say an ignition miss maybe.

But this past week has had lows in the single digits and high in the teens and low 20's, and it has the problem even after being warmed up and driven several miles. Maybe if I drive it 10 miles and park at a store for 15 minutes and the engine heat soaks it'll be ok, but the cold air is really messing it up. What could be affected by the cold air like this? I do not have a CAI on it, just the stock airbox intake under the hood, not connected to the computer to draw air through it. It draws in underhood air.

Any idea what the problem might be? There are no fault codes showing. I used to have an old 1971 Plymouth Valiant with a modified /6 2 barrel and headers, and it would act like this in cold weather (since there was no intake heat from a stock exhaust manifold), but I put in some aluminum dryer ducting, wired to the front header, to heat the intake air and it was happy like that.

It's a stock 2.5 Turbo engine, stock Garrett turbo, non intercooled. Recent maintenance work in the last 2 months included changing the fuel pump and fuel filter.

[black86glhs]

No codes? Can you hook up a scanner and see what the coolant temp is reading at startup? When was the last time a tune up was done? Also, check the fuel pressure. Something makes me wonder about the pump possibly going bad again. If the pressure and flow are good, it rules it out and you can move on to other things.

[Tim]

I have gone through the car for pre-winter maintenance in the last couple months. Spark plugs were changed, I replaced the HEP with a "newer" one that had only 105K on it when the old one started going bad, oil change, checked the timing, changed the timing belt, etc.

It seems to be directly temperature related.

[RoadWarrior222]

Could be yer injectors getting a bit gummed up, but you should be seeing codes like "rich adaptive limit" reached or something. Could also be water/ice crystals in the fuel system.

So, magic snake oil to improve both is to try sticking a bottle of 99% Isopropyl alcohol through with a full tank of gas.

[RoadWarrior222]

Oh, also if you've stuck 20W50 in it, it could be finding it a bit too thick for winter.

[mpgmike]

There may be an alcohol issue already. Our cars were designed for no more than 10% alcohol. With the new methanol blends at the pumps, your fuel pump may be bad again, or even injectors getting chewed up. Alcohol has no lubricity. Check fuel pressure if none of the other recommended checks work out.

Mike

[dwh4784]

Maybe your AIS isn't functioning? Mine is disabled but to where it won't throw a code, I have to warm it up with my foot on the gas for a few minutes before it will run right. This time of year it is kind of annoying.

[black86glhs]

Mpgmike has good points. Also, you changed the plugs but not the wires, cap or rotor?

[Tim]

The cap and rotor were changed last summer, same plug wires from 2 years ago. New (well, 5000 miles now) RN9YC plugs.

I came home from work today in 18 degree air and the car had the problem. Then I was at home about a half hour and left, and the car ran fine, as the engine heat had time to get through all engine parts. Then the car sat another half hour or so in the cold, and when I left to drive home it ran smoothly again.

Something is not working right when it gets cold. Could be an AIS or some other part, I just need to figure out what it is. I can get it code scanned tomorrow and see what is there that isn't lighting the check engine light.

[dwh4784]

When you first start it up will it idle on it's own or does it need a bit of throttle? If the AIS is functioning it shouldn't need any input from you. With my AIS completely blocked off it will die without some extra throttle for the first few minutes, but then it's fine regardless of ambient temp (just takes longer to warm up). Once I see my wideband start bouncing around stoich it's ready to go.

[Tim]

It will start and idle fine on its own even in sub freezing weather, it's only when you try to load it (like when accelerating) that it starts sputtering and dropping cylinders all over the place.

[RoadWarrior222]

I'd go through the grounds and electrics then, sounds like weak voltage until something expands slightly from heat or dries out.