Wont start from cold

Martiny · April 28, 2008, 08:40:27 AM

Guys
After my engine swap, I think my FD has a sensor disconnected or faulty. It starts fine when warm. Its cold starting thats a problem.

originally, I thought it was flooding, but every time I removed the plugs, there was not fuel on them at all.

Yesterday when I switched the car on, I noticed the fan runs immediately when the ignition comes on, and no, the aircon is not on.

I replaced the plugs with new 7\'s all round, and it made no difference, and thats kind of when I realised that the car "thinks" its hotter than it actually is. It also has very little power when cold, I can only use about 1/10th pedal or else it wants to die. warmed up, it runs and starts fine.

What should I check? Where does the ECU get water temp from?

Jit · April 28, 2008, 08:43:08 AM

water temp signal is on the rear plate under the oil pressure sendor and oil filter base

leon · April 28, 2008, 09:12:43 AM

The ECU gets the temperature reading from the top sensor at the back of the waterpump housing. (i had a ()*Â£ of a problem caused by that one recently) You could always if your using a standard ecu check to see if you get any error codes. That at least would tell you for sure if you have one a sensor out, but not if you have a intermitant one.

From my experiance the ECU makes the car run pig ritch as if its flat cold when the watersensor is out. (could be why you have cold start problems) My sensor used to only go skewy when it was hot and quite often cut the engine out.

nikp · April 28, 2008, 09:13:20 AM

The ECU will use the temp sender that on the back of the water pump housing.

nikp · April 28, 2008, 09:26:21 AM

I had a coolant problem on friday. The coolant temp wasn\'t going over 40 degrees, and even started going down a bit. Thought it was thermostat stuck open, but radiator was really, really hot. Also, car was bucking off throttle and was tricky to start from hot. Turned out I had the coolant temp sensor wiring plugged into the fuel temp sensor (which in my case was just cable tied within the engine bay, hence reading air temp) and the fuel temp sensor wiring plugged into the coolant sensor. Hence, the ECU thought it was really cool, when in fact it wasn\'t. They\'re both green plugs.

Martiny · April 29, 2008, 06:51:54 AM

Quote from: Jit;494312water temp signal is on the rear plate under the oil pressure sendor and oil filter base

That one is for the temp gauge. I doubt the ECU cares what that one says.

Martiny · April 29, 2008, 06:53:14 AM

Quote from: nikp;494322I had a coolant problem on friday. The coolant temp wasn\'t going over 40 degrees, and even started going down a bit. Thought it was thermostat stuck open, but radiator was really, really hot. Also, car was bucking off throttle and was tricky to start from hot. Turned out I had the coolant temp sensor wiring plugged into the fuel temp sensor (which in my case was just cable tied within the engine bay, hence reading air temp) and the fuel temp sensor wiring plugged into the coolant sensor. Hence, the ECU thought it was really cool, when in fact it wasn\'t. They\'re both green plugs.

mm, maybe I\'ve done something similar!

Thansk Nik, I will check that.

Jit · April 29, 2008, 09:48:05 AM

oops lol! learn something new everyday! So the one from the back housing...that one only feeds the gauge?

nikp · April 29, 2008, 10:20:25 AM

The one on the back plate feeds the temp gauge on the instrument cluster....and that\'s it!

nikp · April 29, 2008, 10:21:21 AM

Quote from: Martiny;494651mm, maybe I\'ve done something similar!

Thansk Nik, I will check that.

No worries Martin - les us know what you find out.

leon · April 29, 2008, 01:19:08 PM

There are two on the back of the waterpump housing the top one feeds the ECU the one bellow it the gauge from my understanding.

nikp · April 29, 2008, 01:39:16 PM

Quote from: leon;494765There are two on the back of the waterpump housing the top one feeds the ECU the one bellow it the gauge from my understanding.

No, the one below it is for the rad fans.

Martiny · April 29, 2008, 04:36:23 PM

ok, I found that the plug with 2 wires, at the back of the water pump, was loose. In fact, the clip to hold it on, is broken. So I did a Heath Robinson with cable ties to hold it on for now. I dont hear the fan running constantly, so I reckon its fixed !

I will see if it starts tomorrow morning ( it better, i have a performance appraisal at 9!).

I think the second plug, in the thermostat housing, you\'re all on about, is the sensor for the water level.

m1tch · April 29, 2008, 04:41:53 PM

what ecu codes come up?

nikp · April 29, 2008, 07:12:53 PM

Quote from: Martiny;494842I think the second plug, in the thermostat housing, you\'re all on about, is the sensor for the water level.

No, there\'s often a second sensor on the back of the thermostat housing, on the same side as the ECU temp sensor. It\'s for switching on the fan for one of the speeds.

Glad you sorted it though, I\'m sure you have!