6 replies to this topic

[minisilverbullet]

Hi all,

i am battling with a problem of a slightly erractic idle and what feels like the throttle sticking open (the cable is 100% free moving and suitible lubed, so its not that). I have had many different chains of advice here and i am working through the various possibilities. However today i poped in a new air filter (the old one was a bit far gone) and the erractic idle seems to have gone; fingers crossed, the car is now idling below 500, as appose to 900 - 1500! Although this seems like an all to simple fix to me?

While reading various old posts on the forum regarding the above problem, i stumbled across posts on the temperature gauge. I have noticed that for me the gauge never goes above slightly higher than the blue (it does move; between below and slighty above the blue), once on a long 2 hour drive it almost reached halfway! I am now thinking that there may be some sort of a problem somewhere.

Is that normal?

Where and what should i be checking?

oh and where is the auxiliary fan (if i have one) is it the yellow fan within the radiator housing? if it is this also runs constantly.

Cheers

Craig

[datsun100a]

sounds like you need a new thermostat, sensor is giving you a reading . aux fan is in the passenger side wheelarch.

[minisilverbullet]

Ok thermostat, that would be nice! recommend testimg it in water way , heating the water and watching for it to expand etc or just replace it. i think they should be rather cheap!

Any other suggestions of what it could be or if there is even a fault!

[Sprocket]

have you had a read through this?

http://www.theminifo...showtopic=20533

[minisilverbullet]

have you had a read through this?

http://www.theminifo...showtopic=20533

Thanks Sprocket!

I have done before and just finished reading through that thread and the 6 or 7 you posted a in the first post. Was a great crash course in teh injection engine! However I cant see related problems.

I too have an erratic idle like most of the posts. normally its just below 800 ( i assume now from the threads that this is normal). but on ocassion it can rise to around 1500 or fall to around 400. This is very indermitent!

Also on occasion it feels like the throttle is sticking open, i am convinced that this is not the cable sticking. when it happens i lift the pedal with my toe but there is no movement. If i restart the engine the problem dissapears.

While reading through various posts i also came across the problem of the temp gauge (what this topic began on). Basically the gauge barely moves I.E its either below the blue line or slightly above it.

I was thinking about changing the thermostat and its gasket, does this effect the temp gauge?

What would you recommend on the erractic idle:
- replace the inlet temp sensor?
- and the other one (is it the cooling sensor)
- the stepper motor? i will check that as described the link you posted
- reset the ecu by unpluging it for 20 mins (was thet your advice) or did i read it some where else.



Many thanks in advance!

Craig

[Sprocket]

Ok

Coolant temp gauge should always read midway around the white line when the engine is warm and you are driving. If it never gets far out of the blue, there is a problem. Chances are it is the temp sensor itself that is faulty, but it is not out of the question that either the thermostat is stuck open, or, the thermostat is infact sitting in the head rather than the sandwich plate. It may also be possible that the manifold coolant pipes are connected the wrong way round.

You need to fix this first!!

You may find that the idle speed has been adjusted (incorrectly) at some point to try and bring the idles speed down due to the coolant temp reading low and basicaly running on choke that will raise the revs. You need to chaeck that the stepper motor is functioning correctly. this can easily be done by getting some one to turn the ignition on and then back off. you will then be able to see the stepper motor retract, hear a 'clicking' and then see the stepper motor advance the throttle linkage. If you do not get any of this, the stepper motor function is fault for one or more reasons.

Your auxilary fan mounted in the wing, if it is running all the time will be fixed by replacing the thermostaic switch in the bottom of the radiator at the front of the car just behind the grille. to prove this just remove one of the wires from the switch and the fan should stop. if the fan does not stop, the relay could be stuck closed.

All this is assuming the car is un mallestedand and has standard functionality. I say this as I have seen some REAL bodge jobs both mechanicaly and electricaly, and no man on the earth will be able to provide any sort of diagnosis without actualy seeing what the mess looks like that the previous owner(s) managed to create.

Start at the begining and check everything, that is why I pointed you to the link above, you may not relate to the problems, but if you follow the checks and fixes, you wont go far wrong. Its only then, when you are still having problems that you have to start looking for the unconventional 'previous owner' fixes

Edited by Sprocket, 01 December 2009 - 10:53 PM.

[minisilverbullet]

OK great advice thanks for that.

The car is 96 total standard and unadulterated its in pretty great condition having only done 55,000 Km. The erratic idle started a couple of weeks ago.

I will start with the thermostat and work onto the coolant temp sensor (seems a bit tricky to get too).

Many thanks again!

Craig