83 280ZX accelerating problem

[Zed Head]

Wan't really clear.

 

If it's only one wire, there's only three things to look at - the plug (losing ground for some weird reason), the wire (losing continuity), or the electrode in the cap.  Above 2000 RPM, the rotor will be in a different position relative to the cap electrode as the mechanical advance turns.  Could be that the spark is jumping to a carbon track in the cap and bypassing the #5 electrode.

 

Losing one spark is an odd problem though.  Are you sure you didn't just imagine it?  Over-hope?

[jmw_man]

Wan't really clear.

 

If it's only one wire, there's only three things to look at - the plug (losing ground for some weird reason), the wire (losing continuity), or the electrode in the cap.  Above 2000 RPM, the rotor will be in a different position relative to the cap electrode as the mechanical advance turns.  Could be that the spark is jumping to a carbon track in the cap and bypassing the #5 electrode.

 

Losing one spark is an odd problem though.  Are you sure you didn't just imagine it?  Over-hope?

 

Sorry about not being clear. That's why I had separate sections for "while the engine is warming up" and "while the engine is hot".

 

Definitely not imagining it though.

 

I'm surprised if it's the plug, wire, or the cap, all three are fairly new, (couple years old but only a couple hundred miles on them).

Edited April 26, 2015 by jmw_man

[Zed Head]

The coil and ignition module put out an electrical pulse when the reluctor passes the magnet in the distributor, and it just follows the least resistance to ground,  Shortest gaps to jump along the way.  Where the rotor is pointed determines the shortest gap in the cap.  Just basic stuff, follow it out and see what you find.  Could be a defect in the cap or a stray piece of wire that got in there somehow.  The cap is easy to pop off and inspect.  The 280ZX distributor also uses the six pointed reluctor so you can't even have a bad tooth to screw things up.  Since you don't see current flowing in the wire (no light), it must be at the cap.  Could also be that your #5 wire isn't seated properly and the gap is too big to jump (not good for the ignition module, by the way).  Reseat that wire and try again.

[jmw_man]

Well, for a very brief moment this morning I thought I had it fixed. I started with checking the plug and put a socket on it to loosen it, it took barely anything to break it loose. I can only imagine how loose it might have been when the engine is hot. So naturally I assumed the plug must have had a bad ground and went ahead and tightened. I drove it, no change.

 

I got back home and visually inspected the distributor cap and rotor. They still look as brand new as the day I got them. I refrained from putting the old ones back on because the contacts on them are so eaten away. I guess it doesn't really matter for testing purposes so I'll go ahead and do it the next time I have time to look at the car. I did make one observation while I had the cap off and I'm not sure it matters. I advanced the rotor with my hands but at some point while I was advancing it the distributor shaft would stop rotating but the rotor would twist a little bit more. It makes me wonder if the rotor is slightly loose or something. Maybe this only happens when the plastic material of the rotor gets hot and flexes a little too much. I'll try putting the old rotor on and doing a test.

 

Let me just point one other thing out, another observation that I mentioned before on a previous post but didn't describe it right. It sounds as if my exhaust is constricted. The tone of the exhaust is fairly deep. The car didn't makes this kind of noise before this problem started. Anyways, yall might be able to tell me that the sounds of the exhaust that I'm hearing is most likely due to the fuel that's being sprayed into the number 5 cylinder and not burning off.

 

It's really hard to diagnose this car because I get about a 1 hour daily window to look at it. Half of that time has to be spent driving it to get the temperature up. The rest of my day is filled with work and a crying baby.

[Zed Head]

Better to trust the test instruments than appearance or newness.  If you're positive that there's no spark on #5 you need to fix that.  No spark, no combustion, no power, out of balance, rough running.  Another way to test is to remove the injector connector.  If idle quality changes, that's a good sign that there is spark.  

[jmw_man]

Another way to test is to remove the injector connector.  If idle quality changes, that's a good sign that there is spark.  

 

Remember though, number 5 only stops sparking at approximately 2000 + RPM. At idle it sparks, so if I pull the injector connector then the idle quality will change. However, it would be interesting to see if my exhaust still behaves as it does if I were to pull the injector connector. I might try that.

[Zed Head]

Forgot about that.  You have an odd problem.  Kind of hard to grasp without actually seeing it happen.  Just one cylinder losing spark at mid-range RPM just doesn't make sense.  If ir were my problem I would spend a lot of time confirming that that is really happening.

[jmw_man]

To be perfectly honest, I think I have more than one thing going on with the car. I'd be willing to bet that if I put the timing light on the number 5 that there would be a spark there again and that the lack of spark before was due to a bad ground associated with the plug. I'll throw the timing light on there again tomorrow. It might still be a fuel problem.

 

Oh and I hate to say it, but I think I got a bad module from Rockauto with the reman'd dizzy. Even when I went to NAPA in search of a CHTS they all said that it's probably the module.

 

I've already done all the diagnostics on the module and everything checked good but I'm going out on a limb to say that the diagnostics are insufficient. When I ask the question of "what changed" between when the car ran as it was supposed to and when it didn't, the answer is the car received a new distributor with a new module attached. This will be easily tested if I throw my old one on there tomorrow.

Edited April 26, 2015 by jmw_man

[Zed Head]

Which module is on the distributor?  E12-80 style with just one connection, or the E12-92/93, with two?  Some people have reported problems with the modules that have the extra terminals.  

[jmw_man]

two connections

Edited April 26, 2015 by jmw_man

[Zed Head]

http://community.ratsun.net/topic/56630-e12-92-retard-or-no-retard/

[jmw_man]

http://community.ratsun.net/topic/56630-e12-92-retard-or-no-retard/

 

Interesting read. I'll have to do a bit of research.

 

The module on my old distributor is aftermarket, brand is Standard. There are no part numbers on it. 

I'm not sure what's on the distributor from rockauto, will take a look tomorrow. However, both modules have the two connections.

 

Off to look for some schematics.

 

Edit:

Okay, after a brief glance at the wiring diagram, I see that this could actually go back to the throttle position switch as Site mentioned. I tried to take the cover off before but it doesn't look like the cover comes off. I guess I can just unplug the side connector at the dizzy and check the leads for voltage at high and low rpms.

 

Edit:

As you can see, I hate adding posts, prefer to just add to existing if I'm the last poster anyhow. Makes the content a little denser.

I just unplugged the side connector, the car is cold and I turned the key to on. The thermo switch was sending battery voltage and the throttle position switch was not sending anything. I started it up, the thermo switch was sending battery voltage still and throttle position switch was sending 10 volts (not sure if it was supposed to be battery voltage, please advise). I revved up the engine (baaarely) and the thermo switch sent a higher battery voltage (14 volts) and the throttle position switch dropped down to about .2-.4 volts or something along those lines. Now, the engine is still cold so I'll check it when it gets hot. When it's hot and it works like it's supposed to then I guess I need to point my finger at the module.

 

Edit:

Okay, once the engine finally got warm, I tested for voltage in the two wires going to the side connector in the distributor. The wire that comes from the throttle position switch was still dropping to around .2-.3 volts when the engine was revved up. The wire that comes from the thermo switch was zero. I'm guessing the thermo switch is supposed to send battery voltage before the engine reaches operating temperature and then the voltage completely drops away? Seems like it's working as intended.

 

Well, since before I had mentioned that number 5 wasn't getting a spark and I also mentioned that I thought I might have a bad ground, I figured I should get the timing light on there anyhow. This is going to blow your mind, but number 5 is STILL not receiving a spark when the engine is hot and revved past 2k rpm. I threw my old wires on there and again number 5 didn't get a spark. I guess the next step is to pull the spark plug out, put an old one on there, and put my old dizzy cap on there.

 

I have just one question though, does the module send a constant current or does it pulse? If it pulses, is it possible to skip the same pulse in a pattern?

Edited April 27, 2015 by jmw_man