97 Aurora stalls when cold
 

Hello everyone,

I'm having a pretty annoying issue with my newly acquired Aurora. It's fairly cold out, around -8C. When the engine has been sitting and I go to start it up, it runs fine for the first few seconds but then the idle begins to drop and you can feel the car beginning to shake. Sometimes the idle will jump all of a sudden to 2K RPM for a second then drop back down. The idle runs around 1K RPM then goes down even further and finally stalls. This will happen in my driveway and at the nearest stop light if I don't let it warm up enough.
Hitting the defrost button helps sometimes and the car starts right back up after.

Here's the kicker - after a few minutes when the temp gauge starts to creep up, everything runs just fine and it's like there's no problem. At stop lights the RPM gauge seems perfectly still at around 6-700rpm in drive (if you look very closely you can just barely see it move) and when the engine is fully warmed up the temperature gauge stays just under the middle mark, where it should be.

I tried cleaning out the throttle body fairly thoroughly (couldn't get too far in though) as there were some fairly hard carbon deposits and sprayed down the idle air control valve but it doesn't seem to have helped much.

This morning, around -13 C it threw a "service engine soon" light as I took a corner (traction control and ABS don't work but that's a different issue) so I'm hoping it'll help me solve the issue.

Until I get ahold of an OBD II reader to find out what the code is, does anyone happen to have any insight? The car has 140 000 KMs on it if anyone's wondering.

Thanks a lot!

might be better off taking the throttle body off to clean it and the iac. did you clean the tb where the iac seats?

My first thought is the crank sensors. The Northstar engine had a ton of issues with them and might be causing your problem.

I just sprayed into the IAC hole so maybe I didn't clean it enough? I have to say taking off the bottom bolt on the thing where the MAF sensor is mounted with a tiny wrench was the most frustrating part of the job and drained me of a lot of energy which I could have used to clean it more thoroughly!

75 racer: I have a funny feeling this may just be what my issue is - if the code I pull has to do with the crankshaft position sensor it's almost sure thing that's what's causing my issue.

no sense guessing until you get that

Exactly, I think we'll leave it at that until I figure out what the code is.

Alright I got myself an OBDII scanner and here's what I'm getting:

P0300 Random Misfire Detected
P0101 Mass or Volume Air flow circuit range/performance (came up twice for some reason)
P0135 O2 Heater Circuit (Bank 1, Sensor 1)

The check engine light turned off as I was driving today so it's a little iffy.

Could there be a blockage somewhere in the intake?

misfires are normally cause by something else. the 135 the o2 heater warms the sensor so it can work quickly. if the heater wasnt working that would explain some of your symptoms because as the car warms so would the sensor(just from the exhaust). i would check to see if you power there if so replace it, clear the codes and see if the 101 come back

manual says tan/wh and ppl/white wires are the heater, see if you get voltage there with the key on red lead on one black on the other

But wouldn't the car run rich until the O2 sensor is warm? Surely if it's running rich it shouldn't cause an issue. I should mention my gas mileage is very poor - about 15mpg or so combined, I'm sure there's probably something wrong with the O2 sensor but I don't think it's related to the current issue.

I'm going to try unplugging the MAF sensor and resetting the codes, then as I drive it a little more see if any codes come back.