acslater9

Hey everyone I posted a thread similar to this, but this time I'm having the problem where my car wont start in the mornings when the engine is cold.

I have a 91' 240sx with a KA24 engine. Now these are the things I've done to it in the past to make it work. (Thanks to Killer2001)

-Changed Spark plugs
-Changed CTS
-Unscrewed my IACV to idle properly

This problem occurs only when the car has not been turned on, which basically only happens during the mornings. During the day it turns on like any other normal car should. In the mornings I would start the car and It would crank but wont start, and yes I can hear the fuel pump It makes a whirring sound once I stop cranking the car so I know It couldn't be that. I would need to hold my gas pedal down in order for my car start and this takes about 5-6 times of cranking which gets annoying because I sometimes go late to work. Now the weird part about this whole thing is it only happens sometimes, For example I had to start the car up using the gas pedal method this morning but 2 days ago It started right away.

I was thinking It may be my battery but then again I took my battery to Autozone and they said I was good, also my lights and everything works.Anyways I need some suggestions because right now I'm confused as shit. Thanks

acslater9

Alright so something crazy happened like about 20 minutes ago. I went to the bank to grab some cash, I came back tried to start the car on and It just made a tick noise and didn't start. As I did that the engine light would turn on, this continued for about 2 minutes before the car actually turned on. I really need help.

acslater9

Today when I turned my car on It would go up in rpms to about 800 then slowly drop and shut off..Whats going on with it? This is the first time doing it.

Mangudai

Have you checked the cable connections at the battery, alternator, and starter? They should be clean and tight.

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acslater9

I'm bumping this because I'm starting to have probelms again with the starting of my car.

Today when I was getting ready to go to work I tried to start it but it won't turn on. As I stated in my previous post I said that it doesn't turn on when in the cold, yes it still happens in the cold but now its happening when its HOT. Like what the hell is going on?! I havent changed my spark plugs in about 3 months maybe that could be it? Battery is good, alternator is good, starter is good I checked all those at autozone. My fuel pump works I can hear it whinning. Lights all work so do the wipers.

My biggest fear is it being a valve cover leak because I'm not expirenced in engine work. Also most of the time I have to keep pressing my gas pedal just so it can start. Then there are those days when I just turn the key and it starts normal.

I need help any advice is appreciated this is my daily I need this car. Thanks!!

KiLLeR2001

Problem number one I'm seeing is the fact that you shouldn't have your IACV screw all the way unscrewed to idle properly. Which may indicate a bad IACV unit.

Believe it or not I have this issue sometimes with my KA24E, and what I do is hold the gas pedal down about half way as I'm cranking. I think it has to do with a lack of air getting into the engine. Almost certain its either the air regulator or AAC valve in my case.

Check out Page 64 in the EF & EC section of the FSM...

http://www.nicoclub.com/FSM/240sx/91-94/EC.pdf

Run through all those diagnostic checks and report back your findings.

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acslater9

Thanks for the FSM. I have ran into a problem though. I went through all the steps from 1-3 and the 4th diagnosis is the winner. Which is "Check IAVC-AAC Valve".

Fast foward to page 143-144. I did everything in the "A" section and my idle speed did not drop. So I continued onto the "B" section. Now I'm stuck here beacuse the FSM does not state how much voltage terminal "e" and ground is suppose to be. I went to Autozone and bought a multimeter and the crazy thing is I cannot find terminal "e" on any part of the TPS harness. Also what does it mean by Voltage: Battery voltage?

Anyways I decided to check the top half of the TPS and checked the 3rd terminal (meaning the left terminal being 1, middle 2, right terminal 3). My multimeter was picking up negative number like -1,-2 and so on. I don't know if that may be the problem.

My diagnosis would probably be my harness or connector is just worn out. What do you think about it?

*Also sidenote I found out my eng.cont fuse was blown and I replaced it probably about 3 months ago. Could it possibly be a circut thats bad?

acslater9

Okay maybe all that I said may not be true. Just right now I checked to see if my NEW eng.cont 10A fuse was blown, and it was. Maybe this could be the problem I have been having trouble with. I put the fuse yesterday afternoon.

What could cause my fuse to keep blowing like this? I'm not really good with wiring so if someone has the answer can you give me a diagram or explain in depth. Thanks.

acslater9

Just checked my ECU to see what codes come up, and nothing. My ECU throws Code 55. I'm completely stumped.

ultimateirving

Check your alternator cables and grounds. Can cause eng cont fuse to pop.

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acslater9

Thanks for the tip. Also what would I be looking for tore wires? I'm not good at stuff with wiring thats why I'm asking you what should I be looking for when I get under the car.

KiLLeR2001

It's actually terminal B not E. "Voltage: Battery voltage" means you should be seeing the same voltage as your battery, which is 12V.

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acslater9

Well that makes sense. I'll check that tomarrow and update.

As I began this "diagnosis" I'm starting to think my car has a shit ton of problems.

-Engine Control fuse keeps blowing
-Idle is very unconsistant when braking (I think vacuum leak)
-IACV valve might be messed up
-TPS harness is possibly worn out

Starting to think why the guy sold the car for $1700.

Anyways I love this car I wont quit!

acslater9

Found out my TPS harness connectors are not giving the correct amount of power. Checked with my multimeter and was getting 0.1v-0.2v on terminal B which is no where near my battery volts (12.5 volts). Then I followed the diagnostic procedure and decided to check my continuity, fuse (which keeps blowing for some reason), and harness connector which were all bad. And now I need to either repair harness or connectors.

Which brings me to my questions, do I need to completely take out the entire harness of the car? Is there a way to repair the connectors without taking out the harness? Where is the best place to get connectors or a harness? Thanks!

codyace

Truthfully, for the time it takes to troubleshoot, you may be able to get a known good used harness from a car being parted out, and just swap it in.

Don't get me wrong I'm a strong supporter of troubleshooting, but if electrical stuff isn't your forte, it may be best to start with a new (to you) used harness.

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acslater9

So what you're saying is I will have to take out my entire harness out of my car and replace it with a used one? Is there a simple way of doing it? Because I don't think I have ever messed with the harness before, and I'm afraid I'll mess something up.

Alamo_City_210

Its not hard st all. Just take your time. I look things over and over and just see how everything is placed. You will realize that it's not difficult at all

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acslater9

All I need to do is replace the TPS harness, do I really need to take out my entire harness? And if I do how do I perform this task? I've never done anything like it. Thanks

dbeiler

Probably not. How exactly have you diagnosed the problem to the TPS harness? Have you found a broken (open) or shorted wire? If that's the case, a simple splice or some electrical tape will suffice.

acslater9

Well I followed the FSM, and it told me specifically to check the volts of the TPS harness. Terminal "E" which Killer2001 pointed out in the post above that is was actually terminal "B". The volts I was getting were 0.1-0.2 volts and my battery was throwing out 12.5 volts. If I was not getting the same exact volts as my battery, my TPS harness needed to be replaced or connectors as stated in the FSM.

So that's how i diagnosed my problem as I need a (new) used TPS harness. And I checked around and there are no shorted wires.

Any advice on how to replace the harness is appreaciated.

dbeiler

I've never owned a KA harness but I'm guessing it's like every other Nissan harness. Meaning the TPS connector and wiring run all the way to the ECU. That means, to change the "TPS connector harness", the ECU and chassis connectors must be pulled out through the hole in the firewall. Not really a huge deal but does require some patience. Wiring Specialties has harness installation instructions on their website that might help you figure out what all needs connected/unconnected.

acslater9

So basically I can just take out the TPS harness out and replace it with a new used one? I wont have to replace the entire harness of the car right?

acslater9

Could a bad TPS harness cause my engine control fuse to blow? Because every time I put in a brand new fuse the car starts up right away! After the cars been started up a couple of times during the day it begins to show the symptoms of bad starting. So there has to be something wrong with my electrical unit. But I have no idea where to start.

ultimateirving

electrical gremlins are the worst kind, but buying a new harness probably wouldnt be that expensive and could clear up a lot of things. If your worried about difficulty of swapping harness, lay the new harness over the old one and start disconnecting and reconnecting one clip at a time.

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acslater9

Thanks for the advice, but isn't there a way I can just take out the TPS harness out by itself? Why do I need to replace the entire harness out of my car? That's whats confusing me.