Con't saga of HEI weak spark - Doc (or anyone) take a look at these pics please! - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-15-2007, 07:09 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Con't saga of HEI weak spark - Doc (or anyone) take a look at these pics please!

Started testing the various things.

First, heres the settings on my meter:



With the meter set at 200, I measured between TACH and BATT, this was the reading, which seems in spec:


But then I switched the meter to a higher setting, and measured between TACH and the coil center nub, and then between BATT and the coil center nub, like this, with these readings:


No matter where I set the ohmmeter, I get the same reading on this test.

Those are the same readings the meter reads when it's not hooked up to anything. Is that infinity?

Do those readings mean the coil is bad?

That would be odd, because this is a brand new cap/coil. Also, I tried the same test on the old cap/coil, and got the exact same readings. The old cap/coil were working fine when removed from the car a month aqo.

Thoughts? Thanks!

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-15-2007, 07:54 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Doc here,

Unless the pictures are deceiving, your meter is set wrong..

It looks like in the first one it is set to OFF..

And in the second one it is set to Volts not ohms (which is 180 around from the Volts scale)

Test the meter, short the probes set on OHMS..it should read 000, then infinite whit the probes open...Then set the meter for OHMS (bottom left) R X ! scale, do the primary...less than an ohm..but more than 000.

Then set the scale for R X 10 K of higher, and do the secondary, it should read 6,000 to 30,000 ohms..

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-15-2007, 08:03 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hi Doc, the pics aren't very clear, but you are looking at the wrong end of the knob.

In the first 2 pics, it is set to 200 Ohms.

In the second 2 pics, it is set to 20k Ohms.

With that in mind, what do you think of the readings in the pictures?
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-15-2007, 08:10 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Doc here,

ARE you SURE it is set to 200 ohms??

The Rounded end to me seems like it would be the index pointer, and the indented end seems like it would be the rear of the index pointer..

try this: short the probes like it is set in pic 1, DOES the readout go to "000" and hold? IF NOT, reverse the index pointer, and do it again, if it goes to "000" then it's 180 off scale....


Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-15-2007, 08:52 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Yep, I'm sure.

Isn't the second pic proof enough for ya, Doc! If that were off, it wouldn't be showing 00.9 on the screen!

But to put your doubting mind to rest:

Here's set at 200 ohms with the prongs grounded together. For some reason, it sometimes goes to 000, but sometimes not quite.


And here's at 2000 ohm. At this setting, it goes to 000 when grounded.



And here's OFF. It goes to blank screen!


So, I'm getting infinity ohms when measuring between BATT and the center nub, and infinity ohms when measuring between TACH and the center nub.

This seems to indicate a bad coil, no?

But isn't it odd to have TWO bad coils? One on my brand new coil, and the other on my old one that worked fine when removed a month ago?

And if the readings indicate conclusively that both are bad, is there something on my car that is blowing them up? Or it is likely just a coincidence?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-15-2007, 09:40 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Doc here,

Use the 2000 ohm setting...something is not right worth the 200 ohm setting, it may have be overloaded at somepoint..it should read "000" there like it does on the 2000 ohm setting (unless your battery is weak)

If it reads 1.0 on the secondary, the coil is shorted...toss it. If it reads infinity on the secondary, the coil is blown open..toss it..

The readings should be..about Primary: 0.30 to 0.90 (or close to it) with meter set to 2000 ohms, and with the meter set to 20k ,the SECONDARY should read..6,000 to 30,000 ohms..(or close to it)

Anything else is a bad coil, OR it is shorted inside the cap when it was installed to ground (check to be sure)

Bad coils aren't uncommon out of the box but I'd check BOTH, to be sure the old one may not be bad at all.

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-15-2007, 11:05 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hmm. I went to the parts store and tested some of the coils they had, and got the same readings as mine.

I took the distributor out of the car, and using a set of jumpers, attached the negative post of the battery to the distributor body, and + to the BATT post on the distributor, and gave it a spin. It sparked pretty good.

So the distributor seems to be working . . .

I think next I'll try putting it back in the car, and running it with a direct ground from the negative post of the battery to the body of the distributor, and a direct line from the postive post of the battery to the BATT post on the distributor.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-15-2007, 11:39 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well, I thought that was going to work for sure, but it didn't.

How can I be getting spark when I take it off the car and attach it directly to the battery, but no spark when I put it back in the car, but still drive it directly off the battery?!?

I'm not getting weak spark, I'm getting no spark at all. (Earlier today, I did notice at least some very weak sparking at the plug that I had pulled).
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-16-2007, 12:42 PM
larryblack's Avatar
Certified Lead Foot
 
Last photo:
Join Date: Jan 2003
Location: Houston, TX again
Age: 63
Posts: 519
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Do you have a good ground from the battery to the block? Then make sure you have a good wired connection from the alt to the block too. Too many let the mechanical connections be the electrical and that sometimes don't work so well.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-16-2007, 12:50 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Yes, the ground from the battery to the block is good, it is all new hardware and cabling.

The grounding from the alternator to the block, hmm, I don't see any, that seems to rely on mechanical connections. And the alternator is held to the block by way of a long aluminum bracket. Is that not sufficient? (That is how the car has run for 14 years).

Also, I intend to test run the distributor off a completely separate battery. If I connect the + post on that battery to the BATT post on the distributor, and connect the - post on the battery to the body of the distributor (using jumper cables), the distributor should fire, correct?
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-16-2007, 01:57 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Quote:
Originally Posted by Porschev
Hmm. I went to the parts store and tested some of the coils they had, and got the same readings as mine.

I took the distributor out of the car, and using a set of jumpers, attached the negative post of the battery to the distributor body, and + to the BATT post on the distributor, and gave it a spin. It sparked pretty good.

So the distributor seems to be working . . .

I think next I'll try putting it back in the car, and running it with a direct ground from the negative post of the battery to the body of the distributor, and a direct line from the postive post of the battery to the BATT post on the distributor.
Doc here,

First off, your OHMS scale on your meter may be damaged, it may at some point got an accidental DC voltage and fried the precision resistors inside the meter, at any rate , It doesn't sound right, AND I wouldn't trust it until you have it checked out..

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-16-2007, 02:02 PM
Big Mouse's Avatar
Stroked Z28
 
Last photo:
Join Date: Oct 2006
Location: Escaping the rat race...
Posts: 230
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Have you checked the ignition module in the HEI? If you don't have a spare one, beg borrow or steal one. A bad module will stop an HEI dead in its tracks.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-16-2007, 02:04 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I agree - although the meter seems to read correct on some measurements (for example, the measurements between the BATT and TACH prongs shown in the pictures above seem to be accurate), something seems wrong with the meter and I am no longer relying on it.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-16-2007, 02:04 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Quote:
Originally Posted by Porschev
Well, I thought that was going to work for sure, but it didn't.

How can I be getting spark when I take it off the car and attach it directly to the battery, but no spark when I put it back in the car, but still drive it directly off the battery?!?

I'm not getting weak spark, I'm getting no spark at all. (Earlier today, I did notice at least some very weak sparking at the plug that I had pulled).

Doc here,

Because the Module as well as the coil relies on a good ground..If your engine as well as your Dizzy is not getting THE SAME good ground, it won't fire..REMEMBER: The PLUGS share the same ground..

A weak coil may provide enough of a jolt to fire ONE plug with a spark, but not enough to fire 8..with a usable spark.

If the module were going thermal, It may be shutting down after a few seconds..Did you have that tested?

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 02-16-2007, 02:05 PM
Registered User
 
Last photo:
Join Date: Jan 2007
Location: USA
Posts: 86
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Big Mouse
Have you checked the ignition module in the HEI? If you don't have a spare one, beg borrow or steal one. A bad module will stop an HEI dead in its tracks.
But doesn't the fact that it sparks like crazy when I take it off the car and hook it up directly to the battery, as described in my post above, mean that that module and the HEI are good?

("I took the distributor out of the car, and using a set of jumpers, attached the negative post of the battery to the distributor body, and + to the BATT post on the distributor, and gave it a spin. It sparked pretty good.")
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Chevy HEI - Weak Spark daveturnbull Electrical 5 07-25-2011 09:58 AM
Ignition system info................ poncho62 Electrical 18 10-11-2008 10:10 PM
Accel HEI; no #2, some weak, some strong 360Camaro Electrical 2 11-18-2004 06:17 AM
HEI: No Spark Goobzilla Electrical 17 04-17-2003 12:27 AM
350 hei no spark daddyj Engine 3 01-01-2003 12:32 AM


All times are GMT -6. The time now is 09:14 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.