7AFE Runs rough when cold, Until the car gets close to warmed up, the engine runs poorly Options

[GriffGirl]

When I go to start my car, particularly in the morning after it's been sitting all night, the engine feels like it's kind of "chugging" or "hicupping" until it's warmed up. I noticed this right when I bought the car, about 6 weeks ago, and that the temperature gauge was taking forever to go up into the "warm" position.

So naturally, my thermostat must be sticking, right? Well I replaced the thermostat last weekend, and while the car warms up at a normal rate now, it still does this weird "chugging" thing from the time that it begins to warm up until it's about 2/3 of the way to temp.

I did notice that the day after I replaced the thermostat, the car didn't do this. I also noticed that there was a slight leak from where the upper radiator hose goes into the engine block (my fault - I took the wrong thing off in search for the thermostat housing, and didn't use enough sealant when I put the mounting back on). So when I fixed the gasket seal and put everything back together, it resumed it's chugging thing.

Could this be because of air in the line? I'd think it would overheat if there were air though. Bad coolant? It's almost as if there's a vacuum leak, but I can't find one anywhere, and it just seems directly related to the cooling system since the duration that the car does this has also decreased with the proper warm up time in place now.

Any ideas? Thanks!

[K-ESD]

Check your coolant sensor, if it isn't working correctly (ie: loose connection) it will mess up your ECU and it might not set the correct fuel trim for cold idle.
Also, you might benefit from a IAC and throttle body clean aswell.

[Bitter]

Check your coolant sensor, if it isn't working correctly (ie: loose connection) it will mess up your ECU and it might not set the correct fuel trim for cold idle.
Also, you might benefit from a IAC and throttle body clean aswell.

however when the car is at running temp she would also have runnablity symptoms like very poor gas mileage and the engine would feel sluggish, also it would fail emissions badly with very very high HC

not to mention if it were 96 or later it may also set some OBD2 codes for the engine being cold for too long, but i dont think that the obd1 has codes for that.

This post has been edited by Bitter: Sep 24, 2007 - 9:29 PM

[GriffGirl]

Check your coolant sensor, if it isn't working correctly (ie: loose connection) it will mess up your ECU and it might not set the correct fuel trim for cold idle.
Also, you might benefit from a IAC and throttle body clean aswell.

however when the car is at running temp she would also have runnablity symptoms like very poor gas mileage and the engine would feel sluggish, also it would fail emissions badly with very very high HC

not to mention if it were 96 or later it may also set some OBD2 codes for the engine being cold for too long, but i dont think that the obd1 has codes for that.

Gas mileage is phenomenal (considering my last car was a 4Runner, and I drive 40 miles a day commute). Averaging 400 miles to a tank. Runs great once the car is warmed up, has no symptoms whatsoever. As for DEQ, I haven't had to run it through, tags are still good, but I'm guessing considering the condition other things were in on the car when I got it, that this has been a fairly long running problem, likely existing at last DEQ inspection. I feel very strongly that if I had to run it through DEQ today, it'd pass. I'm going to check the connections on the coolant sensor, and poke around for maybe any vacuum leaks, bad hoses, that sort of stuff this weekend. I'll follow up with any findings.

This sucks! It's getting colder in the mornings, and once it starts to rain, I think this is really going to be a problem. Ugh!