idle issue once again

[Baz]

idle issue once again- PARTIALLY FIXED!!!

Recent problem I'm having,When starting the morning the throttle has to be blipped to get it to fire up and the revs slowly build up to 1200-1400rpm after 30 seconds. And then is fine when the car is warmed up ,I have it idling around 950rpm but at night when the head lights are on the revs drop instead of rising. the idle up adjustment screw is doing nothing but the solenoid is working fine

 

[imp124]

I sorted my idle out, it was a leak in the intake where the bypass valve gasket is. Sure you will sort it though mate (Y)

 

[Baz]

Hmm might be there:laugh:

 

[Baz]

I've been busy last night and today ,hopefully this sorts it out once and for all(Y)

 

[Baz]

Right I stripped down the Idle screw assembly and cleaned it and the took apart the cold start valve and cleaned and put the two units back together.

Now the car idles at 2000rpm when cold but the revs drop to 950rpm after a few mins so that's that sorted but may need a cold start valve to get get the proper cold start idle speed of 1400-1800rpm.
But I'm still having the the revs dropping when the engines under load. I've traced the problem I'm only getting 7.8volts at the idle up solenoid and adjustment of the idle up screw does nothing so I disconnected the connector and put 12v on the solenoid and the I heard a click and the car idles up and the adjustment screw has an effect on how much the revs increase when under load.

So then its the wiring? But my question is , is there a relay between the idle up solenoid and the ecu?

 

[Ed]

No, the ECU is directly connected to the solenoid. I need to check the pintouts, its possible you will always have a 12V on one side of the solenoid and the ECU then connects to ground, but there are one or two actuators that work the other way around. I'll have a look for you tomorrow.

 

[Baz]

Yes I found that out Ed yesterday when I stripped a spare loom I have, pin 47 on the ecu (cable colour grey with a blue line through it) goes straight out to the idle up solenoid and connects to the black cable on the other side of the solenoid's block connector, the other larger cable( black with a white line through it) is originating from pin 26 (power for sensors) which come out of the ecu and branchs of into a few different directions one being the MAF and the idle up solenoid. I was thinking the ecu goes to ground at pin 47 but when I turn light/fan etc on it does'nt seem to.

Now I did get a fault code 12 ( MAF ) but I solved this by replacing a dodgey connector and left the batt disconnected over night to clear the fault code and I am now getting a 55 ( no malfunction ) would it just be a case that the car has to be taken for a drive to relearn its parameters ? I've seen this done on a nissan figaro website and the guy who works on them says the car wont be 100% until driven for a couple of km after resetting the ecu.

Or on the other hand maybe it is the MAF and it not showing a fault?

 

[Ed]

Or ecus are not that clever and fig ecus are even more basic. They learn lambda settings but almost as soon as its warm they do that. You dont need to unplug over night either, my job would take forever if that was true

 

[Baz]

Or ecus are not that clever and fig ecus are even more basic. They learn lambda settings but almost as soon as its warm they do that. You dont need to unplug over night either, my job would take forever if that was true

lol ok how do you do it so? Right could it be a lambda? I doubt it is but out of all the components like cold start valve, tps, lambda and MAF could one of these cause the IDle up solinoid not to engage under load?

I was thinking while looking at the ecu pin out diagram would it be possible to rewire it so that it engages seperate from the ecu?
Like pin 24(blower fan switch), pin 44(rear demister), pin 45(head lamps) and pin 46(engine cooling fan) are all signals going to the ecu are they not?

 

[Ed]

I was thinking while looking at the ecu pin out diagram would it be possible to rewire it so that it engages seperate from the ecu?
Like pin 24(blower fan switch), pin 44(rear demister), pin 45(head lamps) and pin 46(engine cooling fan) are all signals going to the ecu are they not?

Yep, those are what causes the idle up to turn on, and as well engine temp, and current rpm. Measure the voltage from pin 47 with the solenoid disconnected with the engine near as 600rpm as you can get it and then again with the engine at 1200 rpm disconnected still. Also measure the voltage on the loom side from pin 47 to ground. It sounds to me as though the driver within the ecu is damaged.

 

[Baz]

Yep, those are what causes the idle up to turn on, and as well engine temp, and current rpm. Measure the voltage from pin 47 with the solenoid disconnected with the engine near as 600rpm as you can get it and then again with the engine at 1200 rpm disconnected still. Also measure the voltage on the loom side from pin 47 to ground. It sounds to me as though the driver within the ecu is damaged.

Its not though as I have a spare ecu and its the same thing. I have ordered a cold start valve because even though the car will idle when it cold it cuts out if the throttle is not held for 2 or 3 seconds then it will idle at 2000rpm which is a little too high . Would the ecu recognise this and shut down idle compensation? So your saying rewire it if all else fails. I know its not exactly the right way of going about it but in all honestly Ive had the car 4 years and I've never once seen it idle 100%,although its the case with allot of st's Ive seen, but mine is by far the worst

 

[Baz]

Found the problem!!!!

Its the ecu:laugh: the two I have are dodgey so i got a lend of one from someone near me that has his off the road atm. put it in and solenoid engaged no problem:laugh: Everything works as it should.

So I suppose one for Ed, can it be repaired or can I rewire it seperate to the ecu's control?

 

[Ed]

I can prob fix. Send me one over if you want and i'll have a look.

 

[Baz]

I can prob fix. Send me one over if you want and i'll have a look.

I'll pm you now