Z24 engine help

[rustrocket]

So the Z24 engine in my nissan vanette is having some issues. It hasn't been driven since 2007.

 

I fired it up for the first time the other day. It idles great, no problems. But as soon as you give it some gas and try to drive it under load, the thing dies unless you meticulously feather the throttle.

 

Unloaded, you can rev it up to about 2300, where it falls and almost dies, then bounces back to a smooth idle.

 

Any idea what this could be?

[MicroMachinery]

Definitely sounds like a fuel issue. The having to feather the throttle makes me think accelerator pump, but if it were only that, you should be able to rev higher than 2300. Have you changed the fuel filter? It sounds like it's starving out, so I'd change the filter and take a look at the fuel pump too. If it's not supplying enough fuel to the carb, you'll only get so much from it then it will fall on it's face.

[datsunaholic]

Is it carbbed or fuel injected?

 

If carbbed, I'd say clogged jet or just a flow issue (clogged lines or filter)

 

If EFI (throttle body?) then probably something in the air sensing circuit (not sure what the Z24i used to sense air flow). Or the cold-start system is stuck on.

 

If it has some sort of air-sensing flapper valve (the old K-jetronic based EFI used a Air Flow Meter) look for a mouse making home in it.

[rustrocket]

Well it's an '87, so i'm pretty sure it has some sort of fuel injection.

 

I'll open it up this weekend and see what i can find.

 

If it is the cold start system, how do i diagnose that?

[datzenmike]

It'll be a Z24i and have two wing nuts on the air filter.

 

There is a fail safe system that senses if one of the injectors malfunctions. It allows the second injector to take over, doubling it's load. This will max it out much sooner and results in an engine that won't rev above 2,800 RPMs. Check for a loose injector wire?

 

You can also 'pull the stored fault codes' from the ECU under the seat? The code for injector is 43.

 

To retrieve the fault codes, start and warm engine in neutral if standard and neutral/park if automatic. Be sure the mode selector on the ecu is set to OFF, after turning ignition OFF.

 

Turn mode selector to ON.

 

There should be two LED indicators, a RED and a GREEN . The RED is for 10s for example two flashes of the RED would signify a 20, 3 flashes is 30 and so on. The GREEN is for single digits, three flashes for 3 and four flashes for 4 and so on.

 

Before proceeding, be sure that the ecu is flashing 23 and 24 .... 2 red and 3 green and 2 red and 4 green

 

Depress the gas peddle fully and release. The ecu should now only flash code 24.

 

Depress clutch, shift into any gear, release clutch, depress clutch and place back in neutral and release clutch. For automatic shift into any gear and return to neutral or park.

 

ecu should now be flashing code 44.

 

44 means everything OK. If it flashes any other code write them down and save.

 

Turn mode switch to OFF wait 2 seconds, turn ignition OFF

 

Finished!

 

CODES

 

11 crank angle sensor

 

12 air flow meter

 

13 water temp sensor

 

21 ignition signal

 

23 idle switch

 

24 neutral and clutch inhibit switch

 

32 start signal

 

42 throttle sensor

 

43 injector

 

44 all self diagnostic systems... OK

[rustrocket]

Thanks Datzenmike! Can i pickup a scanner or something at any autpoarts store to let me do this?

 

I did try swapping ecus last night, no dice.

 

It'll rev to about 5 k though, but as soon as you try and load it up a little with the clutch, it dies.

[datzenmike]

No scanner. The ecu self tests and has flashing LEDs on or in the case. I am using the procedure for the Z24i in the 720/D21 pick-up but I'm sure this will be the same as it is a similar year.

 

The ECUs seldom go bad it will be a sensor from sittling.

[rustrocket]

So, either I'm blind or there's no lights on the ecu. I'll have to double check again. Are they on the top?

 

Interestingly enough, I was looking in the engine compartment, and noticed the twin plug and twin coil system. I unplugged the first coil and it didn't start at all. I put that back and then unplugged the 2nd coil. The thing started right up, and would freely rev with almost no hesitation almost to redline.

 

Under load, It still sputted a little bit but not nearly as bad as before, and evemn got it up to 3500 rpm while driving. A 2000 rpm improvement under load.

 

I'm thinking of grabbing some coils from the conveniently recently junked '88 van at the local junkyard.

 

Thoughts?

[datzenmike]

Ah that's different.

 

Check the fuse. On the 710 it's the one on the extreme left of the fuse box marked ignition coil, could be the same for the Van? If not sure check them all.

[rustrocket]

IT RUNS!!

 

I went to the junkyard and picked up both ignition coils, and coil wires after thoroughly searching for the coil fuses and realizing there was none. So, I replaced the 2nd coil, kept the original ignitor, replaced the plug wire, and it fired right up. There was a little bit of hesitation under load when it was cold, but after warming it up, i was able to drive it to the gas station for a couple gallons of gas and a much needed window cleaning. Then i drove it for about 20 minutes up the expressway and around town. Got it up to 65 mph and felt rock solid. The tranny seems a little notchy, but i'm guessing i probably need to bleed the clutch and maybe even change the trans fluid.

 

The heater works great, the a/c is halfway decent, but the ice maker doesn't blow very cold :-(

 

Overall, a small victory! Now to fix the exhaust leak and get this thing smogged and registered!

[datzenmike]

The 720 has the intake coil directly to the ignition and the exhaust through a fuse???? Why? I have no idea, makes no sence to me. The D-21 is likely better. I know they use a different coil and a power transistor to fire them. Glad you got her going.