setting timing on 2.8 - trick to disable ECM advance?
 

I'm going to be working on the distributor on my 2.8 this week.

Question about disabling the ECM advance while running the timing light.

I watched a youtube vid where I guy was setting timing on a 2.8 in an S-10 pickup truck. Instead of unplugging the ECM connector on the distributor, he just grounded the "A" and "B" terminals on the ALDL connector under the dash before adjusting the timing.

Interested on your thoughts on whether the A/B paperclip trick works the same on Camaro as it did for the S-10.

I know I could just unplug the connector on the distributor. But I figure the fewer times I yank on those old connectors, the better my chances that I don't bugger the connector with ham-handed technique. So, the A/B thing sounds appealing.

BTW, my 2.8 is a manual transmission car, so SIX degrees BTDC instead of 10 degrees?

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Isn't there a est connector ?
https://www.thirdgen.org/forums/v6/6...s-located.html

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Yes, there is.

My question pertains to disabling the EST function by just sticking a paperclip in the ALDL instead of fishing around the hot area between the motor and the firewall for the connector on the distributor.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Try it to find out.

The EST/BYPASS connector isn't by the distributor. It is over by the HVAC bulge on the passenger side. Up top and easy to get to. Single tan/blk wire with an inline connector.

RBob.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

I prefer disconnecting the Bypass wire, then I know for sure it's base timing. I do this even for my DIS equipped engines to set or verify base timing/sensor position.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Dug into it today with the notion of replacing the distributor O-ring first.

Plenty of evidence of oil leak around the distributor, so figured I should address that, and then set the timing.

After an inordinate amount of wrestiling, I got the distributor out, and found THIS:


https://cimg4.ibsrv.net/gimg/www.thi...786866c780.jpg

Re: setting timing on 2.8 - trick to disable ECM advance?
 

:eek: :eek:

Re: setting timing on 2.8 - trick to disable ECM advance?
 

The amazing thing is, it was running fairly decent (only stuttered a bit on-and-off) before yanking this out.

After lying across the motor for much of the afternoon, and including two trips for tools and parts, it was time to call it quits before I could get to the timing light.

I did fire it up, and high-fives were given to my good buddy Bob and to my wife for their help and patience.

It fired instantly, but was idling noticeably rough. Seemed to sound "normal" when I ran the RPM's up.

I just couldn't bear to climb on top of that motor again today, and wrestle that distributor lock-down bolt.

But, on the topic of it running rough:
I did disconnect the battery during the installation. I thought I did about the best job possible orienting the rotor, and the distributor body, respectively to match the positions of the old unit.

Anybody think the rough-running might be a function of the ECM needing to do a re-learn after the battery-disconnect, and becoming "acquainted" with the new distributor?

Should I take it for a spin to see if the roughness abates?

Should I tackle the timing before driving it around the neighborhood?

How important is it that the motor be completely warmed-up before setting timing?
I realize that timing is a strictly mechanical thing, and in-theory should be able to set base timing irrespective of whether motor is cold or warm.

I'd rather mess with the timing when the motor is cold, because that business of having to lie across the motor, and feed that crows-foot wrench down into that tight spot in the back of the motor is not an experience I'm looking forward to - let alone atop a hot motor.

Advice appreciated.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

:) The most helpful advice I could think of here is this ;


You will find , if you play with the tension of the hold down bolt a bit , you can make it so that the distributor is "somewhat difficult" but not of course "impossible" , to twist . You get the hold down bolt to that tightness , the tightness that causes a kinda hefty twist to be needed to move the distributor , and then with the proper base timing connector disconnected you set the timing by difficultly twisting the distributor that will stay in place where you set it , because you have just that right amount of tension on it that you can move it but it won't move by itself , and then you shut off the engine and while watching that the distributor doesn't move you tighten the hold down bolt that last 3/4 of a turn it needs to lock the distributor in place .

Whew , got all that ? Bonus points for once more checking the timing to make SURE ya didn't move it when giving the bolt that last 3/4 of a turn , then go do the whole disconnect the battery to clear the code thing , hook back up the advance connector and the battery and you should be good to go .

PS , you don't want to know how I do MY timing :eek:

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Here is the video of the guy bypassing the EST on his S10 by jumping the A/B

Jump to the jump by FF to about the 4:00 point of the video.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Gonna work on mine when I get a break later today or tomorrow

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Hot as Africa in the driveway today, but I couldn't stand to wait any longer.

Took it for a little drive to see if the rough idle in the driveway would improve with an ECM learn. Cut off on me several times at stop signs. Drove it home.

Diconnected the battery.

Disconnected the ESC.

Reconnected the battery.

Attached timing light pickup to #1 plug lead.
(V6 2.8 cylinder #1 is front passenger side).

Not much point in checking the A/B jumper trick in the ALDL, because it looks like I need to deal with the timing chain if I want to get any sort of reliable read with the timing light.

For now, I'm just going by ear and feel to achieve "least worst" driveability.

Watch the timing mark jump all over the place.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Hey man, have you made any progress with this? Im in the same boat!

Re: setting timing on 2.8 - trick to disable ECM advance?
 

I put a new (Carbone brand - "rebuilt") ECM in it today.

Swapped the existing PROM chips into the new one.
Easy job.

Old ECM was throwing 42 and 54 codes at me.
New ECM - no "check engine" light. Which is a good thing.

Ran it around on the highway for a while today. Lots of WOT.
No stuttering. Which is a good thing.

Timing mark still very, very jumpy.
Looking more-and-more like its a timing chain/gears issue.

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Wow, you're making some fine progress. Thank you for the update! Ha, i've hit mine with my purse so many times over the years.....but, i'll never give up. Please keep us updated...it's starting to get good now, brother!

Re: setting timing on 2.8 - trick to disable ECM advance?
 

Mind you, that vid is our northern brother, Klowny, showing how it needs to be done.

I may get to that point, but for now, my sights are on getting the front suspension in better shape. Every piece of rubber - and probably the struts too - are all 29 years old.

For the time being, if that "stutter" thing with the motor will stay gone, I'll live with it not quite purring like a kitten.