Easier to start when engine cold. Why?

[rnln]

I found/confirmed that my car is much easier to start when it's extremely cold, as in the morning. Usually, I barely twist the key, and the engine is running healthy already. At noon, it's much harder to make it turn over. Sometimes, it can take up to... maybe 3 seconds to have it turned over.
Why? How can the little different in weather's temperature makes the different?

[DRACO A5OG]

The Usual Suspects:

Cylinder Head Temperature Sensor (is it a 1 or 2 wire CHTS?)
DME Relay (You should have a spare, if you do switch it out and see if the issue returns)

[rnln]

I have no idea where the Cylinder head Temp Sensor is and don't know where to find it to see if it has 1 or 2 wire. Can you help pointing it out? What is CHTS?

Also, I read somewhere someone said the big black square relay under driver seat is the fuel pump relay. Now, after a little search, I found that it is the DME relay. If so, then where is the fuel pump relay. I only have one relay under the seat.

[dshepp806]

DME is a "dual" relay...for both DME AND fuel pump.

Do a search on the CHT and you'll find an evening's worth of reading...

Best,

[DRACO A5OG]

Hey No Problem Rnln,

1st, the DME relay is the Fuel Pump Relay. You should always carry a spare one anyways. Some members have even re-soldered it but at $30, better to buy new and keep it in the trunk for emergency road side repairs.

2nd, the CHTS, you need a digital current meter (Radio Shack sells them), if not just check to see what type of CHTS you have.

Open the lid and remove the cool intake air housing held by 2 screws on top and a hose clamp at the bottom. Once removed you will see a three set of wires held by a metal housing. The set starts with an off white plug ( the CHTS ) from the top. You will see it right away if it is single wire or double wire.

If you want to test the sensor, there is a retaining metal clip that requires a plyer to pull off then use a small flat head screw driver to unclip the white plug off. DO NOT PULL ON THE WIRE ALONE use the housing only. Use the digital meter to test. Do a search on CHT and someone posted a chart or look in the Bentley Service Manual (Get it, it is worth it's weight in gold!, Amazaon sells them for $76).

The other option is to raise the car on the driver's side and pull off the rear wheel and behind the shock absorber is the CHTS within the sheet metal heat guard to the #3 cylinder head. Check the wire to see if it is single or double wire.

Replacing takes 2 hours and $75 and a special tool (14MM deep socket with a minimum 1/4 cut out on the side of it) for proper 11lb torque. Member has used a needle nose plyer to their satisfaction. I am bit OCD and need the right tools to do a job.

Here is a link to what the CHTS looks like and the steps to replace it:

Head Temperature Sensor Replacement Credit goes to Clark G! :-)

Hope this helps.

[rnln]

Yes, it helps a lot. What you described sounds much like the O2 sensor or very closed to it? Thank you very much guys. Another reading for tonight, or maybe weekends.

Originally Posted by DRACO A5OG

Hey No Problem Rnln,

1st, the DME relay is the Fuel Pump Relay. You should always carry a spare one anyways. Some members have even re-soldered it but at $30, better to buy new and keep it in the trunk for emergency road side repairs.

2nd, the CHTS, you need a digital current meter (Radio Shack sells them), if not just check to see what type of CHTS you have.

Open the lid and remove the cool intake air housing held by 2 screws on top and a hose clamp at the bottom. Once removed you will see a three set of wires held by a metal housing. The set starts with an off white plug ( the CHTS ) from the top. You will see it right away if it is single wire or double wire.

If you want to test the sensor, there is a retaining metal clip that requires a plyer to pull off then use a small flat head screw driver to unclip the white plug off. DO NOT PULL ON THE WIRE ALONE use the housing only. Use the digital meter to test. Do a search on CHT and someone posted a chart or look in the Bentley Service Manual (Get it, it is worth it's weight in gold!, Amazaon sells them for $76).

The other option is to raise the car on the driver's side and pull off the rear wheel and behind the shock absorber is the CHTS within the sheet metal heat guard to the #3 cylinder head. Check the wire to see if it is single or double wire.

Replacing takes 2 hours and $75 and a special tool (14MM deep socket with a minimum 1/4 cut out on the side of it) for proper 11lb torque. Member has used a needle nose plyer to their satisfaction. I am bit OCD and need the right tools to do a job.

Here is a link to what the CHTS looks like and the steps to replace it:

Head Temperature Sensor Replacement Credit goes to Clark G! :-)

Hope this helps.

[DRACO A5OG]

Actually the O2 Sensor is totally seperate issue but please read the CHT thread it will be very helpfull and the DME is a 10 second fix.