Someone please help before I torch this thing

 

Just been rebuilt, has run away fine until out of nowhere during cold idle it hunts, then drops well below 1k revs and dies

 

If I keep a bit of throttle on and warm it up it isles rough as guts when until it's warm where it seems to be okay.

 

Took codes, faulty temp sensor, replaced no change.

 

Found the throttle bodies were out of sync and not closing fully. Fixed and no change

 

Went about the set idle procedure. Idles good

 

TPS has been adjusted

 

Had the idle control valve off, cleaned and connector ohm tested.

 

Have the air regulator apart and seems to be working.

 

Plugs out cleaned and gapped.

 

Don't have access to a boost leak tester but done the carb cleaner around all hoses and nothing.

 

I'm lost, and losing hope, anyone able to help?

Temperature sensor connection needs cleaned and checked

the hunting on idle sounds a bit like mine and u had to rev it to get it right, i had a of set ngk c plugs in as soon as i put the old b's i found in the back of the cupboard the car was back to its old self again

Already done the temperature sensor. Don't think plugs are a problem as it's run fine for a while until now.

You say it ran okay for a while?

Have you done anything that may have disturbed something recently?

All that's been done near the engine is had to fiddle with the exhaust as it wasn't sealing properly. otherwise nothing.

All that's been done near the engine is had to fiddle with the exhaust as it wasn't sealing properly. otherwise nothing.

 

Hunting diagnostics (2) from FSM step 1 - check 02 sensor connections:

 

ec70-71.pdf

I was just about the suggest O2 sensors too. Unplug them, that may well fix it.

My Green one did that for a while. I think it turned out to be the MAF and a CAS problem

Sadly these cars are quite complicated when it comes to problems like this. The first approach is to ensure all your electrical connections are in good shape, this will include the cable from the ptu to the cas, the connector on the maf, connectors to 02 sensors, idle valve and the tps. I would also include the injector connectors and plug connections. Its a bit of a list l know but anyone of these will cause the engine to run rough. You may also need to check your fuel pressure which is a bit moredifficult without the proper equipment. Ideally you need Conzult or similar to be plugged in which should give a general health check to most of this and the actual set up of the engine. What sort of condition is your engine bay electrical loom ? these deteriate over the years due to the heat generated by these engines making the connectors brittle and the copper connections inside weak. Sadly patience and being methodical is the name of the game.

Loom is in ok condition, I took the chance when the engine was out to clean all connections with baking soda, tooth brush then needle filed them.

 

New injector connectors and double checked them and they all are good.

 

I have a gauge at work somewhere to check fuel pressure

 

Have done the diagnostic mode for o2 sensors and that seems to be all ok.

 

Think I'm going to have to make some kinda boost/smoke leak detector through the week and make 100% sure there are no leaks.

Did you disconnect the o2 sensors to test?

 

Here is a useful guide on boost leak location (or vacuum leak when off boost):

 

http://www.thumper300zx.com/z32/boostleaks/boost_leak_guide.htm

 

5 psi is considered the safe maximum for pressurising intake system whilst testing.