raleighBahn

Hey folks,

Recently I've had some intermittent no start, primarily when warm. Usually it would start after a few tries or waiting a few minutes. I was overdue for some vacuum leak testing, so spent some time and found a leak and fixed. I did this over the course of a few days as time permitted - so car has been off for about four days. After putting back together, I now have no start (from cold). I consider this a good thing as I have the problem in front of me with all my tools.

So now, from cold, I get an eager crank, but no tach bounce.

Here is where I'm at:

• Leaks - none
• Swapped known, good DME relay - no change
• Jumped the fuel pump relay - pressure at rail is 46 psi. Fuel leak down good.
• Used simple ignition spark tester on cylinder 1: NO SPARK
• Used Ignition Spark tester inline between distributor and coil - NO SPARK
• Primary resistance for coil is .5 ohms (good range is .4 - .6 ohms)
• Seconday resistance for coil is 5.89 K ohms (good range is 5 - 7.2 K ohms)

So I have no spark from the coil, but the resistance readings are in spec. Where is the next logical place to check? I'm guessing S&R sensors and DME, but don't want to go down any unnecessary rabbit holes until I need to. Thanks!

raleighBahn

OK - I gave the S&R sensor wires a little jiggle - from sensors to harness plug, and then on other side of plug. Car started.

Hmmmm... wondering if this is wiring or seating.

Tom M'Guinn

Peel the rubber boots back (harness and sensor sides) and take a peek. I'm guessing you'll find frayed wires. The harness connectors used a potting material to secure/protect the wires, but unfortunately it ends up cutting at the wires over time.

lart951

Hmmmmmm.

raleighBahn

Tom, I will do that for sure once the car cools off again. That would make sense as I barely jiggled the wires - not enough to change the seating of the sensors themselves (and it looks very clean down there).

Egads, I'm just not in the mood for contorting myself to replace any wiring - I supposed I'm lucky it's not the DME. I do have an adjustable 3bar FPR on order which is supposed to be here today; should help fix my rich condition (46 psi with ignition switch on, 40 psi with car started and vacuum line connected).

Tom M'Guinn

I started by trying to replace the connectors on mine, but the shielding is a pain and you only get little stubby wires to work with. I got it together but wasn't happy with it so eventually swapped in a patch harness (LR, 944online, etc.) and was happy to have it all new and fresh from the DME connector all the way to the sensors. It's not the most terrible project you'll ever have anyway.

shortyboy

speed reference sensors. change the harness and sensors at the same time.

raleighBahn

I hate the footwell. I need to find a small child to be the tunnel rat and go down there.

fiily

Mine had that same problem, the speed/reference connectors on the DME side were toast(cracked and brittle from 25+ years and heat) behind the intake manifold, broke apart in my hands.

Cheap fix, wire in new ref/speed sensor harness and done.

$100 fix

http://www.lindseyracing.com/LR/Pors...4-HAR-REF.html