triscadek

What actually compensates for cold weather starting?

My 87 S always starts but runs very rough for the first several minutes and the idle is a wump wump wump until it reaches normal operating temp.


Bad temp sensor somewhere?

quinnfiske

There is a temp sensor that sends a signal to the DME. It is located in the head toward the front of the engine under the intake manifold. It has a connector on it like the injector connectors. They are only about $25 or so and it is worth replacing if it is the original (probably is).

whalebird

also, the air flow meter has a air temp sensor circuit, There is an easy test in the DME test plan that simply ohms out the pins at the meter. I don't know the values of hand. After market chip??? I have seen chips not work well at really cold starts. one of the trade-offs of some chips

gtroth

Is it idling high when cold (~1050rpm) or its normal ~850rpm? If not you might start to think about servicing the ISV.

Engine temperature sensor ("NTC II") is tough to get to on the S (pull the intake manifold).
First measure it on pins 45 & 24 on the DME connector:
0°C = 4.4~6.8Kohm
15°C~30°C = 1.4~3.6K
40°C = 1.0~1.3K
80°C = 250~390ohm
100°C = 160~210ohm

Same values for the air temp sensor in the AFM ("NTC I"), by the way (pins 44 & 26 on the DME connector).