New truck to me, z24i electro-injection woes

[Notapilot69]

49 minutes ago, datzenmike said:

What happens when opened suddenly?

 

I've seen the Z24i in the 720 and I have the 86 D21 Z24i FSM but I know they are not the same engine.

I'll give it a shot. I read in the FSM that the TPS acts to measure current position as well as the rate the throttle is opening or closing, that makes me think it's related to my issue 

[datzenmike]

On 7/13/2020 at 11:17 PM, Notapilot69 said:

 

 

Advancing the throttle slowly allows the engine to rev to redline. If I go wide open anywhere from idle to 5k rpm+, it falls on its face like a slow rev limiter. Tach goes to zero as well until it fires again, then back to zero. Seriously like a really slowly alternating rev limiter. 

 

 

 

Advancing throttle slowly..... is this in gear driving?

[Notapilot69]

Mike, rapidly depressing the gas in gear, out of gear, neutral, or by hand, all has the same effect

[datzenmike]

No, what I want to know is when you rev slowly to redline..... is this while driving?

[Notapilot69]

Both, I can recreate the cutout and run it to redline both in gear or not, driving or not. Apologies for the confusion 

[TommyBsolid]

I have had a similar problem with a D21 Z24i, slowly opening throttle was the only way to get it to rev up or it would stall. I don't know about the tach dropping to zero, mine didn't have a tachometer. My problem was timing being too retarded, check your timing with a timing gun, make a mark on the crank pulley to see it easier, use exhaust spark plug wire on cyl#1. Specs of how many degrees before TDC should be label on the underside of the hood, the distributor unbolts and can rotate to adjust timing. Also the timing begins to advance as throttle opens up and vacuum in the intake manifold builds, set the timing while engine is idling. Hope this helps.

Edited July 16, 2020 by TommyBsolid

[Notapilot69]

Thanks Tommy, I'll check it again but last time I checked timing was 10°, I'll check the manual to see if anything needs unplugged to make sure I checked it correctly and see if that's right 

[datzenmike]

Timing is 5⁰ +- 2⁰ on the Z24. They are dual plug design so the burn time is much shorter so the advance is less.

[Notapilot69]

Do I need to unplug anything to check timing properly? Or just leave it since there's no vacuum advance 

[datzenmike]

I don't think so. Better check though this is a crank angle sensor?

[Notapilot69]

Yessir it has a crank angle sensor. Pops a code for it too. 

[Notapilot69]

Does anyone know much about the switch in output on the TPS? The FSM shows the voltage output changing from one pin to another at a certain throttle position, I wonder if it's related. Going to check timing again tonight and mess with the TPS some more. Can get a replacement for $40 might order one afterall

[Notapilot69]

Fellas I'm reaching my witts end here, if anyone has any ideas let me know. Now I can't even keep it idling. Tach no longer works and one of the fenderwell coil is not firing despite having 12v strong. Voltage on the operating coil is all over the place while running. Bounces from 5-12 volts continuously. Reinstalled the cleaned up TPS and it idles horribly at any placement, rotating clockwise and counterclockwise where the screws allow accomplishes nothing. 

[datzenmike]

Sorry, wish I knew more but that's the high end of anything Datsun. When you get to CAS and EFI I'm lost

[TommyBsolid]

When did it stop idling? Was it after pulling the TPS? I have a 1986 service manual with info on z24i, will be going home in a bit and I can post pics on how to test tps. Check spark by pulling one plug at a time and cranking (dont forget you need the thread of the spark plug against a grounded surface, anywhere metal in the engine bay will work). Disconnect injectors so the engine doesn't start. If your not getting spark it could be your coil. Another way you could test is using a timing gun, if you know your spark plugs are good and its not shorting the gap. Btw have you checked timing?

 

If you are getting a code for crank angle sensor I can post picks of how to check that as well.

 

Do you have already have access to a FSM just so I’m not being redundant?

 

I would have offered to come over and take a look if you were any closer to the PDX area, It’s ofter very hard to give useful help through posts when there are multiple issues at play which I suspect is the case.

Edited July 18, 2020 by TommyBsolid

[TommyBsolid]

On 7/15/2020 at 9:24 AM, Notapilot69 said:

11... CAS Crank angle sensor

21...Ignition signal

23... Idle switch

24... Neutral and clutch inhibitor switch

I would start be trying to clear the codes, 23 and 24 are always there when you start the diagnostics setting on the ECU. Get rid of 23 by pressing in the throttle pedal, and get rid of 24 by pressing in clutch and putting it in any gear, wait, then back into neutral. 11 could be a bad CAS, let me know if you need info on how to test it, 21 is ignition signal missing in primary coil. Check spark, if no spark you may have a bad coil. Lift the cap off of your distributor and make sure it looks like it should, the CAS is attached right on the distributor so you may have a compound issue there idk, let me know what you find

Edited July 18, 2020 by TommyBsolid

[Notapilot69]

Thanks for reaching out Tommy. Yes I have a factory FSM and I'm trying to check everything per the manual, but it won't even run long enough to do my due diligence. I need to fix the coil not firing that for sure. It has good voltage but 100% no spark off it. Other coil, which is sparking, has crazy varying voltage constantly. It jumps around from 5-12V while running. Running poorly, that is. 

[Notapilot69]

From my checks it appears the TPS is functioning properly. I'm leaning towards the CAS so I'm going to try to check that now. 

[Notapilot69]

37 minutes ago, TommyBsolid said:

I would start be trying to clear the codes, 23 and 24 are always there when you start the diagnostics setting on the ECU. Get rid of 23 by pressing in the throttle pedal, and get rid of 24 by pressing in clutch and putting it in any gear, wait, then back into neutral. 11 could be a bad CAS, let me know if you need info on how to test it, 21 is ignition signal missing in primary coil. Check spark, if no spark you may have a bad coil. Lift the cap off of your distributor and make sure it looks like it should, the CAS is attached right on the distributor so you may have a compound issue there idk, let me know what you find

Codes I have now are 11 21 and 24 after performing the diagnostics completely by the book 

[Notapilot69]

Maybe that coil is just bad 

[Notapilot69]

Timing appears to be alright but it idles so shitty and low tpm that I'm not 100% sure 

[TommyBsolid]

Take a look at the wiring diagram and trace the wires going to the coils, could be a bad connection somewhere. When I was testing my z24i the intake side didn’t spark on idle, there are vacuum lines going to 2 units on the passenger side of the engine bay attached to the fender, these monitor vacuum and select if either both intake and exhaust fire or just exhaust, double check all vacuum lines to make sure you don't have an intake leak.

[Notapilot69]

11 minutes ago, TommyBsolid said:

Take a look at the wiring diagram and trace the wires going to the coils, could be a bad connection somewhere. When I was testing my z24i the intake side didn’t spark on idle, there are vacuum lines going to 2 units on the passenger side of the engine bay attached to the fender, these monitor vacuum and select if either both intake and exhaust fire or just exhaust, double check all vacuum lines to make sure you don't have an intake leak.

Vacuum lines are a mess right now due to the air cleaned being off for all the testing. I'm about to plug everything in where it goes and see where I'm at just to see

[TommyBsolid]

Make sure you plug the correct lines to the 5 metal lines welded to the air filter housing. Take a look at the vacuum diagram and make sure everything is piped correctly when you assemble it.

Edited July 18, 2020 by TommyBsolid

[datzenmike]

1 hour ago, TommyBsolid said:

Take a look at the wiring diagram and trace the wires going to the coils, could be a bad connection somewhere. When I was testing my z24i the intake side didn’t spark on idle, there are vacuum lines going to 2 units on the passenger side of the engine bay attached to the fender, these monitor vacuum and select if either both intake and exhaust fire or just exhaust, double check all vacuum lines to make sure you don't have an intake leak.

 

 

On the carburetor Z24 one vacuum switch shuts of the idle cut solenoid on high speed deceleration so that the idle mixture isn't wasted out the tail pipe. I assume the EFI idle mix could be easily shut off too. The other vacuum switch turns the exhaust side plugs off during heavy load conditions. It should run ok if these were disconnected to try it.