Engine timing

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Hi...
Wonder if I might ask a question about engine timing?
An older Olds; still with an adjustable distributor.
Fender label says disable the computer, warm it up,
and set the timing to 15 btdc.
Just watching it sit there, the timing "changes itself" by about 5 degrees randomly and almost constantly.
So would the distributor be rotated so that the recommend 15 is the most before it gets, or the average, or....?
Thanks to all who can offer advice.
Take care.
Ken
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What year Olds and what engine?

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David J and Lynne J Shepherd wrote:

Hi...
Thanks for the response...
It's an '85 Ninety-eight. A 3.8 litre v-6.
Take care.
Ken
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Did you disable the computer?

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clevere wrote:

Hi...
Yep, sure did :)
At least I think I did... used one of those mickey mouse (walmart about 20 cdn bucks) code readers... As soon as you plug it in the check engine light comes on...
Take care.
Ken

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timing chain is likely to be worn out.
wrote:

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I second the timing chain...

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A wandering timing mark is not an acceptable condition when setting initial timing. Either the EST was *not* disabled, or there is a mechanical problem (timing chain sloppy). While the ECM can be placed in field service mode to disable EST, the fool-proof manner is to disconnect the EST wire in the engine compartment. Refer to the appropriate service manual for exact wire color and connector location, but they are usually a single inline connecter in a brown wire.
Mark
On Tue, 01 Jun 2004 13:56:51 -0600, Ken Weitzel wrote:

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Marky wrote:

Hi Mark...
Thanks for replying...
I just double checked by putting a timing light on it again. With the code reader plugged in, check light on, I find the mark walking all over, but "surrounding" 15 degrees.
Then pulled out the code reader. Instantly the timing mark rotates almost out of site (more "before") way off scale, and stays there. (but continues with its wandering.
Is that good enough evidence that the ecm was disabled?
If so, guess I'm stuck with the timing chain, and looking at Haynes I'm kinda thinking I'm a bit too long in the tooth to do it :(
Thanks, and take care.
Ken
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Ken Weitzel wrote:

If you don't want to do the timing chain and the engine still runs fairly well, just take the average spot of the timing oscillations and set your timing there. It should work just fine.
Ian
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shiden_Kai wrote:

Thanks Ian. I don't want to (probably couldn't) do it, and I doubt it's worth paying a pro to fix it.
It's an old car; still looks good. But it's only purpose in life is to stay at the cabin, gets used during the summer to put the boats into and out of the water, to move a guest trailer around once in a while, and take down the gravel roads to the store in town on occasion.
The only problems it shows is a bit rough idle, the check light comes on if we let it idle for more than a few minutes, (reader sets lean mixture code), and mileage seems terrible. The mileage is probably related to how it's used. :)
Appreciate the advice.
Take care.
Ken
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If fuel injected; To access the set timing mode, you want zero resistance between pins "A" and "B" of the ALDL. You have no way of knowing whether your Walmart code reader actually puts zero resistance between pins "A" and "B". Maybe spend the bucks on a paper clip?
If carbureted; Disconnect the four wire connector going into the distributor housing.
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Neil Nelson wrote:

Hi Neil...
Yikes! Fuel injected (multi port), but what's an ALDL, and which are pins A and B...
I think I can afford a paper clip :)
Take care.
Ken
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The connector under the dash that you plug your Walmart code blinker into.

They're labeled.

Try a paper clip, if the timing is still jumpy, it could be a warning that the ignition module is about to fail, a intermittent short or open in the ignition coil, a faulty (cracked) pole piece in the distributor or any of a few other things I'm not thinking of yet.

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Neil Nelson wrote:

Hi Neil
Saved up; bought a paper clip :)
Now the problem is that we can't find any label or markings on the connector.
My eyes are getting a little old; my just turned teen grand daughters are perfect. But neither of us can find markings.
Can A and B be desribed by their location?
Thanks, and take care.
Ken
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The lettering is pretty small.

Try here, it's a pretty good picture of the ALDL and the pin-outs:
http://www.gmtips.com/3rd-degree/dox/tips/ecm/aldl.htm
Pay attention to the little keyway tab shown at the top and it's orientation to pins "A" and "B".

You're very welcome.
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Neil Nelson wrote:

Hi Neil...
Fastastic! Unfortunately shows that my little tester dead shorts those pins (actually both "pins" are one piece of metal)
But something learned is great...
And that site is great; all kinds of information! :)
Thanks again, and take care.
Ken
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Someone help me out here............I have documentation somewhere that tells me to place a particular resistor ( I think 1000 ohm) in between two pins to enter the computer into field service mode where the timing and RPM are held at a constant. There is also another resistance that will test the TCC on different pins...anyone know what I am talking about and can refresh my memory??

in
disconnect
service
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Eightupman wrote:

Hi Eightupman... (shouldn't that be seven up man? :)
I'm an old retired electrical engineer, so I know pretty much which pedal to push to go and which to stop; not too much more...
But if it helps, this little 19 canadian dollar walmart code reader does that.
The timing isn't (for sure) controlled by the computer, and the engine rpm stays constant. Well, constant. When normally you start it it goes reasonably fast, then within a few seconds slows down quite a bit. With this device plugged in it doesn't slow.
Hope this helps.
Take care.
Ken
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Eightupman wrote:

Hi again...
Just trying to be helpful a little, I found this page that talks about putting resistors across pins in the adsl (sp?)
http://faculty.eicc.edu/dhanan/ep2/NOTES9rev.htm
Ken
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