ground for distributor!? please read!!

[tmoney]

well as some of u know by looking at my past posts. ive been having lots of backfiring and cutout problems while my car revs up under load. ive tried everything from ignition to fuel to ecu reflashes, etc...

well me and my shop foreman attached a timing light to the coil wire while we went to lunch. we noticed while the engine backfired, the light would flash real slow indicating a loss in spark. well got back to work and another master tech joined us while we were brainstorming. my shop foreman blurted out "try a jumper wire from the dist to the ground on the block (his '52 suburban needed it or it ran like poo). well i did just that on the way home. i made about 4 redline hits without it backfiring on the way home. it ran like i pulled a potato out the tailpipe. **crosses fingers to let it stay that way**

so my question is: how is the distributor grounded? thru the block? dist hold down? has there been issues before about this? i did a search for it and found nothing relevant

thanks all that have tried to help me!!! this site has the best ppl on earth!!

[90TurboVan]

Have you checked fuel pressure under boost? The distributor does not need to be grounded, the HEP sensors are grounded to the ECU with their own wires. Did you try a HEP sensor? Sometimes the wires break inside the insulation right where they come out of the sensor. Check continuity from the HEP connectors back to the computer while moving the harness around.

[MVaughn]

Check grounds on the car. Look closed at the one that is attached to the fuel rail and the back of intake to firewall.

[tmoney]

turbovan- yes checked fuel pressure under boost and it stays the same. also the hep has just been replaced. i saw the insulation cracking on the old hep.

vaughn- i installed the ground wire kit that fwdp sells. it made a huge difference with the way it started and alt charging and lights etc.. and my point being is that it included a fat ground from the fuel rail ground to the firewall. it didnt fix my problem.

since u said, turbovan, that the ground for the hep is to the ecu im gonna do some stimulated wire tests from the hep to the ecu. but until it starts acting up again the unneeded jumper is staying lol

travis

[xrattiracer]

there is nothing in the distributor that is grounded or requires a ground. whatever you did in adding the wire caused the "fix" somewhere else; moving the hep wires or something.

[ZachT]

do you have the stock wires that push onto the pos/neg of the coil. they are a 90deg in the wire at the end with a piece of round copper in there that wraps around the end of the coil plugs.

i had that problem on my car, i found that the wire where it attaches to that connector had broken loose, i redid both and attached them to the coild with nuts. works a lot better now. that could be your problem. if you have the stock coil connectors.

[tmoney]

Quote:

Originally Posted by ZachT do you have the stock wires that push onto the pos/neg of the coil. they are a 90deg in the wire at the end with a piece of round copper in there that wraps around the end of the coil plugs. i had that problem on my car, i found that the wire where it attaches to that connector had broken loose, i redid both and attached them to the coild with nuts. works a lot better now. that could be your problem. if you have the stock coil connectors.

my coil had the eyelet terminals. i saw that the insulation was cracking there too. so i recrimped new eyelet terminals, still same thing

travis

[KitCarlson]

Distributor body grounds are important for mechanical point ignitions. This is not your case with the hep ignition. The points ground the coil (-) to charge the coil and open for spark. If the distributor is not grounded there will not be spark. The distributor locking clamp provides a good ground when tight. When adjusting the timing the clamp is loose and missing might occur.

The timing light does draw some spark energy to trigger the light. If the ignition is marginal to start with, miss may occur. Spark plug wires, worn or fouled plugs, rotor and distributor cap may be the first place to check. Dirt, oil and carbon tracks leak spark energy.

The installation of the timing light also radiates the EMI of the spark and may interfere with the ECU and signals the ECU uses for engine control. The timing light cables act like antennas. This may also lead to misfire.

[tmoney]

great news everyone! its fixed! for some wierdo reason the ground fixed the misfire only when hot, and i flushed that idea (and it had no point of being there). so a few days ago my oil pressure light was coming on at hot idle. so that means new oil pump right?? i got one, pulled the oil pan. and guess what found...... the gear was about worn off on the oil pump. ive read lots of posts about this gear wearing out. so i was getting ready to check this gear eventually but now that i HAD to do it, i killed 2 birds with one stone. so its fixed now yay!! case closed

travis