RichieRoo

Hi all

I've got an issue whereby the car stutters for no apparent reason at cruising speed.
It has to be electrical because all of the power (even dash lights, stereo etc)
goes off for a fraction of a second each time it stutters.

The pain in the butt is that it's intermittent (normally only happening on a long run)
and I can't recreate the fault.

I've fumbled around the ignition key wires, but nothing seems to affect it.
I've also cleaned and polished the front earth points and ensured that the battery
is really well connected.

I notice that lots of people have trouble with the ignition coils, but that
wouldn't explain the dashboard lights going out would it.

An obvious weak points I should check?

Cheers

Rich

Jonnygo1

I had the same problems and found that replacing the main ground from the battery solved it. I replaced the original braided line with exposed copper with a newer style one with insulation from Pelican. It was only around $10, my cheapest fix yet.

RichieRoo

Yeah. I did remove the old braided cable and really cleaned it up (soaked in a corrosion
remover over night) and refitted. I guess it wouldn't do any harm to replace it altogether.

I'll get one tomorrow.

The reason I didn't before was that I figured the car should run fine even without the
battery connected at all as the alternator should provide enough power. So to my mind
the battery earth is pretty much redundant.

But what the hell... I'll try anything.

Thanks

Rich

newsboy

Our cars are very sensitive to electrical problems, so it could be allot of things.Check other ground points, like transmission ground. You could unplug and then re-plug the computer under the drivers seat to make sure there is no corrosion. And then there is always the coils. If they never have been replaced, might be worth a try.

Livefreeandrive

http://www.pcarworkshop.com/images/b...0590geolab.pdf

Now Mandatory reading for all 964 owners.

AOW162435

I think the issue was actually corrosion within the crimped ends of the old braided ground cable. The new one I purchased a few years ago from Sunset was $10 or so.


Andreas

Jeff Curtis

Check connection at starter where the battery cable (positive) is attached after travelling through your 964 on the passenger side.

Also, there is a ground strap from one of the nuts that holds your starter in the transmission bellhousing, the one (bottom) that can be reached from just under the car...this bolts to the "hoop" support for your rear shocks...this can be a MAJOR culprit.

RichieRoo

Ok. I'm liking all the suggestions and plan to address them all.
My check list looks something like this:

Air flow meter wiring - my car is a '91 so I didn't have to remove
the protective wire covering, but I did the wire tie and also found
that the breather pipe bracket was floating around as it had not
been reattached by the last owner when the shock absorbers were
replaced. That has been bolted back down and bend as per the
PDF instructions.

Battery earth cable - I've ordered a custom made earth cable which
is really chunky.

Starter to chassis earth cable - I did the starter motor recently and
went to extreme lengths to ensure that it made a really good connection.
You can see what I did here.

In addition, I have also ordered a thick custom cable to connect from the
engine bay chassis earth point to a large bolt on the aircon compressor.
So this should ensure a good ground to the engine/transmission.

Connection to engine management under seat - I'll disconnect and
reconnect as suggested.

Will let you know how I get on.

Thanks for all the suggestions so far. Really appreciate your help.

RichieRoo

Just took the car for a test run. Looks like it wasn't anything to do with the
air flow meter wiring because the problem is still there.

The hesitation was accompanied by the infamous "Christmas tree" illuminated
dash board (see picture).

Let's hope the new earth leads fix it. They should arrive tomorrow.

Jonnygo1

I would consider doing the coils too. Have you checked the plug wires for arcing (most fun you can have in the dark with a spray bottle)???

RichieRoo

Afternoon all.

Leads arrived today. Very impressed with the service of the company making
them up (Kojaycat in the UK).

Sent them all the details yesterday afternoon. Had an email to say they had
been made up and posted the same afternoon. Arrived this morning.

Lovely quality too (check out the pic). Nice rubber boots on every terminal.

So I've replaced the old braided battery earth and added a cable from the
chassis to a big mounting bolt on top of the aircon compressor.

Has it worked? Well I took it for a short test drive and it seems ok. I'll report
back either way after a proper run. If this fails I guess it'll be Jonny's plan
of replacing the coils.

boxsey911

Finger's crossed for you Richie. Have they kept those details on file? I wouldn't mind ordering a set of those leads myself.

RichieRoo

Hi Boxsey

Here are the specs for the cable. The diagram here shows the braided battery
cable replacement at approx the same length as the original (I did mine a bit
shorter because I have a battery disconnect switch attached).

The longer engine/chassis ground cable connects to my aircon compressor bolt.
If you don't have aircon, obviously the length to a suitable bolt will vary.

As you can see from the photo I allowed plenty of slack in the longer lead
to allow for engine movement. Don't know if it hampers air filter removal -
haven't tried. Obviously the cable is pretty chunky and space to get to the
chassis ground is a bit limited, but it's doable.

boxsey911

Where does the engine compartment strap attach to on the chassis? I've got a braided strap that links the air con compressor bracket to the nearest engine mount bolt. Not being particularly knowledgeable in car electrics I'd never really worked out what it was there for. I'd assumed it was to earth the compressor for safety? But now I'm guessing it's more for grounding the engine?

I think I've got a pic of it somewhere and will post it up if I can find it.

RichieRoo

There is a brass earth point in the rear wing, adjacent to the dipstick pipe.
It uses one M8 bolt to secure two earth cables.

My choice of the aircon bolt was very arbitrary. I was just looking for a good,
solid connection to the engine which was easily accessible.

This extra cable is simply an addition to the earthing loop under the car which
Jeff mentions earlier in this thread.

I believe the small braided cable you mention simply ensures a good earth with
the outer (pulley side) components of the compressor.