jtrav23

Hey guys,

So I posted in here a while back about my s13 that I refreshed the engine and put in a newer shell (89 engine in 92 shell) here?s the link the the previous: Ka24e no idle (fresh engine)
https://r.tapatalk.com/shareLink/top...ink_source=app

I just got back in town from college and installed the new maf that was believed to be the problem along with new dizzy cap and rotor.

I am still having the persistent problem of perfect idle with maf unplugged just slightly rough sounding but when I plug it in the roughness goes away until it chokes itself out.

I know I need a air temp sensor would this cause it to die?

Here is a video of it running with and without the maf plugged in:

https://share.icloud.com/photos/0arA...qO-zwMA#Hurley

(Not sure if this is allowed but I have no other way of posting a video)


Sent from my iPhone using Tapatalk

zombiewolf513

If unplugging the maf makes it better, the maf is probably the issue

jtrav23

I would assume the same thing, though this is the third maf I?ve tried two being brand new.

Unless I?m the unluckiest person alive lol


Sent from my iPhone using Tapatalk

NukeKS14

You tried pulling codes from the ecu? Or tried testing maf wiring from the fsm?

jtrav23

I pulled the codes and only received code 41 which is the air charge temp sensor, I?m not sure how to test the maf that?s why I ended up buying a new one. I saw the fsm description but I?m horrible at electrical stuff related to volt meters and such sadly.


Sent from my iPhone using Tapatalk

NukeKS14

https://www.nicoclub.com/archives/us...-database.html

Comprehensive FSM database.

IAT on the SOHC cars is separate and in the airbox. It does cause a CEL if the delta between it and the coolant temp sensor is too high but ECCS doesn't use it on the SOHC for fuel trims, so that's coincidental with your issue.

If you're curious about the IAT sensor here's more info;





https://www.youtube.com/watch?v=m6EhtMGRivA

Another vid of a rough SOHC. Have you checked your distributor timing? When you disconnect the MAF it throws the ECCS into limp mode, changing your fuel trims and timing both into open loop.

I'd start there. If you verify your dizzy is installed right at TDC, then get it running w/ MAF unplugged and check timing w/ a timing light, I'd go into checking the wiring harness. The first pic I uploaded from the FSM gives you wire colors. Disconnect the battery and the ECU and verify continuity between the ECU connector side and the MAF plug. I had a broken CAS wire once that would cause my SOHC to just randomly die when it went over a bump/pothole. I'd get no spark or fuel then tow it home only for it to run like nothing ever happened. Biggest PITA to diagnose ever. So basically you're going to have a multimeter set on resistance (ohms) and to verify continuity you want a low value when you connect each lead to both ends of the wire. NEVER TAKE A RESISTANCE READING ON A LIVE CIRCUIT.

I'm guessing it's your timing though.


*edit* Also, you need to adjust that TPS! you can't just slap it on. it has to be aligned or the engine doesn't know what the actual throttle position is.
https://240sx.org/faq/articles/throt...or_adjustm.htm

Yeah it's written for a DOHC but it works for the SOHC as well.

It's frustrating when people get half way through troubleshooting their car and decide to start a new thread on it. You lost all of your info from the old thread, stuff you did etc...

jtrav23

Thanks for all the information. I will be going through everything you put here ASAP, though the timing I?m pretty sure is correct but I will recheck it for the 4th time lol. I understand the open and closed maps which is why I?m assuming it?s a sensor just not sure which one, as when the closed map is running off of predefined tables it runs correctly. Though, when the open map attempts to pull readings from the sensors it dies. I will also attempt to adjust the throttle body again but I?m going to have to do more research, just as with the maf I?m not great with a voltage tester. Lastly, the previous post is linked and was not of much help as I had to move states so did not get much further then a maf diagnosis.


Sent from my iPhone using Tapatalk

NukeKS14

It's the throttle position sensor. In this video, the guy shows you how to set up the voltmeter (to read DC voltage) and where to probe the harness with each lead. It's so easy, a caveman could do it.

With it in limp mode with the TPS unplugged you should be able to get a timing light on it and get your base timing set too. I noticed your distributor bolts are all the way loose and it's fully clockwise.

https://www.nissanforums.com/threads...-ka24e.191506/

There are some pictures on a timing chain replacement on a KA24E complete with distributor installation.

Lastly, most people aren't willing to dig through your old posts to find out what all you did to your car up to this point. You never said anything about replacing the TPS in this thread and I believe that IS significant. Whether you succeeded in fixing the issue or not. The inputs your car uses for the closed loop maps are coolant temperature, throttle position, engine speed, and airflow from the MAF. There are lots of other small things like the knock sensor that can change the tables too.

The point being, while it didn't help YOU fix the problem, it helps the people you're asking for help understand what has been done up to this point. Also, if someone has this issue again and does a google or forum search, the chances they hit one of the 'uncompleted' threads is likely. Why not retain your issue to a single location so that others can benefit from the solution too?

jtrav23

Thanks for the video, made it extremely clear and simple! I used a timing light to time it originally but was messing with the dizzy to do some diagnosing so I?ll have to re time it and lock them down. I will also delete the previous thread, I had created that over a year ago and most forums don?t appreciate old bumps like that and skip over them. I completely forgot I had put a different tps on. Hopefully adjusting that fixes the issue, would love to be driving this thing for the summer!


Sent from my iPhone using Tapatalk

jtrav23

After multiple attempts testing the tps it seems that it may be faulty as the harness turns up correct but the pins on the tps has no connection between pins 2 and 3. I?m going to get another tps as well as a air charge temp sensor.


Sent from my iPhone using Tapatalk