[DML] Ignition issue- RESOLVED (long)

["cruznmd" <racuti1@xxxxxxxxxxxx>]

I'm posting this because a few folks have related that are interested 
in my results because they have a similar problem. To recap:

Symptom(s):  Car started well, idled acceptably. All fuel pressures 
nominal by Bosch fuel pressure test rig. All fuel components 
replaced. Car stuttered heavily under load (A/C on, pulling away from 
dead-stop, hard accel), surged when maintaining steady speed, and 
experienced a power fall-off when the accelerator pedal is pressed 
more than 1/3 of the way down. The power curve "drops off" and the 
car decelerates. The engine sound changed drastically, as if 
misfiring.

I'm sorry to say that there wasn't one particular "smoking gun" to 
this problem. It was a many-layered thing. Here are the items that 
caused a noticible improvement as I fixed them:

As David Titlebaum says "Just because it's new, doesn't means it's 
working correctly".

1. My "new" plug wires were SHOT. 2 read "infinite" or "open" on my 
Fluke multimeter. The others 4 read 9k ohms or more. The normal 
resistance for new, plain old store-bought 7mm wires is around 1.5k 
ohms. My new hi-po wires read 350 ohms/ft. 8mm, silicone.

2. My "new" cap and rotor had HEAVY carbon scoring. Uncleanable. Most 
likely due to my plugs being overgapped and failing plug wires. 
Replaced with Bosch plugs of the correct part #, correctly gapped and 
new cap and rotor.

3. Grounds: I replaced the black ground cable that runs from inside 
the coil box to the frame. I cleaned the ground cable behind the 
parcel shelf wall, passenger side. Also, the ignition ECU grounds the 
coil via the white/slate wire. Inside the coil box this wire goes 
from the coil to the yellow plug, pin 3. The pins were -green- and 
didn't contact well. I cleaned these up and crimped the female closed 
a bit. I then checked the white/slate junction in the relay 
compartment. Pics available upon request. 

4. Coil: I have experimented with; Accel, OEM Bosch(blue), 18kv Bosch
(red), MSD Blaster 2.
Of these, (oddly) the red, 18kv Bosch and the Accel coils run the 
worst. For me, they cause a less acceptable idle and performance is 
not as good under load. If I had to hazard an educated guess, I say 
it's because the -internal- resistances are not OEM spec. They are 
higher. I believe to function correctly, they might need a longer 
dwell time to build the proper field in the coil prior to discharge. 
As we all know, dwell is neither readable, nor adjustable on our 
cars. The MSD has the same internal resistance as the OEM coil. It 
idled well and had good performance. The biggest difference I noted 
between MSD and the OEM coil was easier starting, a slightly better 
idle and slightly more horsepower. I'm probably not making full use 
of the MSD coil because I haven't matched it with other hi-po 
ignition components except the wires.

I don't guarantee that my problems are your problems but I make the 
following recommendations:

1. Clean the aforementioned grounds. Use contact cleaner from Radio 
Shack (spray can) and emery paper, then coat lightly with brand: CRC 
di-electric grease. Verify that all spade connections are in good 
repair and tight. Many of mine broke off due to wire-fatigue. 
(especially white/slate)

2. No matter how recently you've done a tune-up, inspect or replace 
your ignition components. I can't stress the word QUALITY enough. I 
tried to cheap out, and it caused me trouble in a couple of areas. 
Bosch, Bougicord, etc. DMCH's Nology and John Hervey's hi-po wires 
are also good (just my opinion).

3. Ensure coil compatibility. Some of you who wrote me also have the 
red, 18kv Bosch coil. I recommend experimenting with the OEM coil, 
but if you have to have a "firecracker", get the Nology kit or MSD or 
Pertronix. I would stay away from Accel and I don't think I trust the 
red 18kv Bosch coil anymore. Whatever you do, try to get a coil with 
the same internal resistance as "old blue".

My power curve is back to normal. No surging, no power drop off. I 
can push the pedal anywhere I like and the car keeps on going. A/C on 
or off. I had to fix -all- of these things to get it that way.

I hope this helps,

Rich A.
#5335




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