jfrc

As the title states, I have no ignition in cylinder 4. My car has sat in the garage for over a year due to this (but in my defense we did have a newborn, I went back to school to finish my degree, have coached 3 youth teams, and have had a stack of honey-do's).

Here is what I have eliminated:
1) swapped coils with cylinders 2 and 4- no change
2) swapped sparkplugs with cylinders 2 and 4- no change
3) swapped plug wires with cylinders 2 and 4- no change
Pulled cylinder 4 spark plug and test for spark- none
I have not found any coil/ignition specific fuses
I have cut back the electrical wire loom to examine the wires for any damage.

So basically cylinder 4 is getting no ignition, possibly due to electrical signal.
Does anybody have the ignition wiring diagram?
Is there any other way to test or trace this?

Please help, I finally have some time to work on her. I am tired of seeing her sit in the garage, collecting dust.

Cutlassmaster

If you don't have the manuals then it would be a good time to get them. How far back did you go on the wire loom? I would suggest a pm to Bill Curlee. He and several others are well versed in troubleshooting electrical and are talented enough to help through email and phone calls. Update what you find out.
GL
Chris

dadaroo

Look at where the wiring loom goes around the back of the motor. There is a bracket there that can cut into the ignition wiring. Actually happened to Bill Curlee if I recall correctly and it was grounding one of his ignition coil wires.

PS: Not sure if your test really ruled out a bad plug. Might want to try a new plug or swap one of the others to that location and test again. Not at home with the FSM right now to post anything for you.

cholmes729

Find out which cavity in the factory PCM is feeding cylinder #4 coil, DARK GREEN/White wire. disconnect from the PCM, unplug the #4 coil, check resistance from the PCM to cylinder #4 coil connector, then check pin to ground resistance. Leave you DVOM on each end of the wire and wiggle the engine harness and watch your readings. If you are getting a resistance from Pin to ground at any point, it is shorting out. If its open, and you cant find it without tearing all the loom off of the entire harness. Run a new wire from the PCM to the ignition coil connector.

www.chevythunder.com I know the guy that runs this website. TONS of Info for TPI and LS engines. Can also build a harness too.

Bill Curlee

Here ya go!

Make sure that you have GROUND, battery voltage & , Ignition Control Signal & low Reff on each coil.

IF,,, you have an old DWELL meter, you can read the Ignition Control Signal from the PCM.

BC

Bill Curlee

ALSO,,,,,,,,,,,,, do a pin pull test on the connector on the COIL and the main bank connector on the entire coil assy. Look for bent, dameged, deformed femal pins!!

coia96vette

Bill is THE man when it comes to electrical problems on these cars. Follow his lead and it will work out.

jfrc

YES!

I began by testing the reading at the connector at each coil, as a comparison. The dark green wire had no reading. I then checked the reading at the main harness connector, and the dark green wire had a reading. I tore apart the thermal wrapping on coil panel, and I found the culprit- the dark green wire had a break in it! I will repair it later tonight (after more youth sports lol).
Where can one locate some new electrical thermal tape?

Thanks for you help everybody.

dadaroo

You should use a piece of heat shrink tubing to seal the soldered joint not tape. However, if you want to tape the wiring bundle together here is some ifo. I have not used it but got the info from my Pantera Forum.

Forum Quote:
I've had really good results with a silicone based,
waterproof, black stretch tape which is readily available (Home Depot,
etc.).

I've used it in engine bays to dress wire bundles, as well as restoring
cracking electrical vinyl "bellows" style (non-replaceable) boots on engine
bay connectors (on other marques), and it's held up for years. It's good
up to 500 F, bonds to itself, chemically (gas and oil) resistant, and is
easy to remove, leaving no sticky residue. In other words, it's almost
perfect for this application. It even comes in a "clear" version if you
need to see the color coding on wires.

Ask for "*Stretch & Seal*" , manufactured by Nashua, in the plumbing
department. It's about $7 per roll. Follow package directions closely for
best results; and in particular, remember it must be substantially
stretched and 2/3rds overlaped to itself for proper application.

There are competitors out there as well that work, but this brand is
substantially thinner, so it conforms better and is easier to work. The
other stuff (i. e., Magic Wrap) is a better choice for heavier-duty
problems.