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Re: BEYOND FRUSTRATION !!!!! [Re: tomzsix] #924039 01/17/09 04:55 PM
Joined: Feb 2007
Posts: 1,167
ghostraider Offline
Body Damage is Cool
***
Quote
I can take my time on this trouble shooting.


i would as it seems like you are chasing ghosts. the coil can be tested by hooking up test wires and seeing what happens while you drive and the problem occurs.

I am not sure of the specs on a 2.6.

Had a coil go bad on a vw bug. Looked and tested fine but would not work intermittently/ Tried a used one from Junkyard and it wasn't long before i forgot that i had a problem...if ya know what i mean.

Draining the gas seems like the wrong thing to do. after all, there is a fuel filter in line and i would check it first. <img src="/forums/images/graemlins/scared.gif" alt="" />

<img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

Re: BEYOND FRUSTRATION !!!!! [Re: ghostraider] #924040 01/17/09 05:47 PM
Joined: Oct 2007
Posts: 184
PatrickS Offline
Wheeler
Quote
Quote
I can take my time on this trouble shooting.


i would as it seems like you are chasing ghosts. the coil can be tested by hooking up test wires and seeing what happens while you drive and the problem occurs.

I am not sure of the specs on a 2.6.

Had a coil go bad on a vw bug. Looked and tested fine but would not work intermittently/ Tried a used one from Junkyard and it wasn't long before i forgot that i had a problem...if ya know what i mean.

Draining the gas seems like the wrong thing to do. after all, there is a fuel filter in line and i would check it first. <img src="/forums/images/graemlins/scared.gif" alt="" />

<img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />


I agree and still do not believe it is a fuel problem.


89 3.0 LWB Montero, 1st Gen, 5 Speed Manual, 5 Door
Re: BEYOND FRUSTRATION !!!!! [Re: tomzsix] #924041 01/17/09 06:27 PM
Joined: May 2000
Posts: 6,132
K
Kevin C Offline
Trail Leader
****
Tom,

If it's the pickup or the module the tach should drop to zero when there is a problem.

The tach senses the voltage on the negative side of the coil.

To create a a spark the module grounds the negitive side of the coil through a transistor. When a spark is needed the module stops the current flow through the coil. This causes the magnetic field in the coil to colapse, generating about 20,000 volts onthe coil wire side and a 200 to 400 volt pulse on the negitive side of the coil.

Putting a scope on the negative side under load will show what is happening on the high voltage side. The tach is also connected to the negative side of the coil and will show complete failures by dropping if the coil stops working.

It wont show a high voltage leak to ground. Thats a bit harder to test under load.

The basics of keeping an engine running are compression, fuel and spark.

The fuel can be monitored by looking at the O2 sensor while you drive. You can also look for an over rich condition by having somone follow you as you drive. You should see a large amount of black smoke when it happens.

The carbs go rich if the bowl vent valve leaks and the motor will die out with RPM and load.

a lean out would be most likely caused by a fuel delivery problem. I would suggest using a temporary fuel pressure gauge to make sure you have fuel pressure under load.

In summary:

I would test for the basics, fuel pressure, and spark. Since you cant easily test the high voltage side of the coil under load it makes sense to try another coil.

The rest of the ignition system can be figured out by watching the tach.

A low cost gauge connected to the O2 sensor can tell you if the fuel system is a problem. The other solution is to put a scope on the sensor lead where it enters the fuel computer by the passengers feet.

You can also use a good digital voltmeter to measure the sensor. A scope probe is better but a voltmeter should work.

Kevin


87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...
Re: BEYOND FRUSTRATION !!!!! [Re: Kevin C] #924042 01/17/09 10:26 PM
Joined: Apr 2004
Posts: 183
T
tomzsix Offline OP
Wheeler
Hey,Kevin... NAPA lists a coil for either around 20 dollars and another for around 40 dollars. they do not show that they come with ballast resistors. should i use the one that i have with the new coil??


Tom Tucker
Re: BEYOND FRUSTRATION !!!!! [Re: tomzsix] #924043 01/18/09 03:10 AM
Joined: Jan 2001
Posts: 13,649
fasteddy Offline
Web Wheeler
*****
You can test the one you have (and I don't remember one going bad). There are two 12v+ wires going to the coil. One has power in ign. start position and goes straight to coil + terminal. The other has power in ign. run position, and goes thru the resistor and then to coil +. This give you a full 12v while cranking for the hottest posible spark, and a reduced voltage to the coil (less coil heating) when running. I think I remember seeing 12v in start and about 7-8v at run. Mine also have a radio noise suppression thingy on the coil +...

$40 coil just because if I tell the the $20 one, and it quits, ....


Not responsible for advice not taken...
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