New Zealand Datsun Club

Could your injectors be gummed up/leaking? That would cause a rich condition that might foul your plugs...........

Does the Z18 run an CHTS ( cylinder head temperatur sensor )

Its just a resistor that changes as temperature rises or falls, and this is usually one of the main sensors that the ECU uses to calculate how much fuel to dump in there.

If this isn't working perhaps it thinks the engine is dead cold when warmed up & then fouls plugs from having too much fuel.

My car used to do the same, ran good cold and once warm just ran like crap, you don't have any vacum leaks or anthing like that ?

85_Z31 wrote:I always thought most of the Nissan ECCS stuff ran hotwires

right you are there mate, all nissan ECCS is hotwire MAF (mass air flow)......however, most of the older nissans didnt have ECCS.

They all ran a AFM (air flow meter). L, Z, FJ, series all ran flap type AFM.....then CA, SR, RB e.t.c. all started with the ECCS in the mid 80's with hotwire MAF.


anyway.....
yes, your theory could be correct.....running rich will foul up your plugs with black shit and make it run like a sack.
Z18's dont run a cylinder heat temp....they run a water temp sensor that is mounted in the thermostat houseing alongside the temp sensor for your dash (but is a separate sensor).....and yes, it could definately be due to a faulty temp sensor, causing your problems, just as 85_Z31 suggested.

in most nissan ECU's, the water temp sensor is a very crucial sensor, and if it goes faulty, it can cause a numerous amount of different problems....youd be surprised how important it is lol.

look it up on the net, and see if you can find out how to test your sensor with a multimeter ( you should be able to stick a meter on it, and it will have different levels of resistance depending on the temp of the water)

if that was faulty would it not come off cold start? (stay on high idle)

Bartman wrote:if that was faulty would it not come off cold start? (stay on high idle)

I was thinking this as well; my car comes off cold start. I felt the radiator hoses the other day after it had only just been started, and they felt a little warm. I figured this meant that the water was passing the thermostat and going into the radiator (shouldn't this happen later once the car is fully warmed up?). My temperature gauge has never read much above the cold line the entire time I've had the Z18ET in, but I never worried about it since it came off high idle after warming for a bit. Maybe it is warming up a little but not enough?

Also, the injectors don't seem to be leaking or anything obvious.

Car is fixed

I got a new thermostat in and now it actually gets up to temperature (hopefully no more fouled plugs).

It was still idling like a sack of shit and then I noticed there was a little vacuum hose not connected (it was when I took the injectors out, but I must have bumped it or something)
I connected that back up and hey presto! now it idles fine. Stoked.

Thanks for the ideas everyone

Did that also fix your heater too?

I haven't checked the heater yet Bart but yeah hopefully it has

The saga continues...

I've driven the B over the last couple of days and everything seemed fine, but then last night the engine started to get really hot (over 3/4 on the gauge) when I was going for a short trip across town. Pulled over andd turned it off so it could cool down. I went and felt the engine and it was so hot I couldn't leave my hand on it. I felt the radiator and that was hot also, so I guess that means the water was passing through the thermostat? (maybe not a high enough flow rate though?)
I waited ages for it to cool down and checked the coolant/water level. Nothing wrong there by the looks of things, the radiator was full. I started her up and drove home and it was getting fairly hot by the time I got back to the garage (I'd only made it about 5 min from home before it got hot).
The thermostat I put in looked slighlty different to the one I took out (Repco doesn't list anything for Z18ET so I used a Z18E one) but I was told that it didn't matter as the had the same temp setting on them (82 degrees C) and the rattle pin was in the same place.

Any ideas?

they're right in saying it doesnt matter.
all you need is the right temp thermostat, and it fits nicely in the hole....

getting hot....maybe your radiator is poked? all filled with crap and only half working? (I had my radiator "rodded out" and it made it heaps better).