My Misc Fiero issues

[Fierofool]

Set your timing with the ALDL jumpered.  Install and remove the jumper with the ignition OFF.  The engine should be at operating temp for best initial result. 

[The Art Doctor]

I think I got it closer just before dark.  Not too familiar with the ALDL I might have not followed proper procedure and messed with it with key on.  Hope I didnt do permanent damage to anything.  I tried to set timing by rpm, terrible mistake.  Almost didnt make to corner and back and pipes were glowing.  Re set to my base mark and with jumper it is back to 1050 and pulls strong.  By the timing light and the tab it is at 8 degrees.  Should I go for 10 or leave it alone?   When I pull the jumper it still goes back to a high idle so something is up.

[Fierofool]

Installing and removing the jumper can reportedly damage the ECM if the ignition is ON.  Two lower terminals on the passenger side of the ALDL.  Now that you have it close, you don't need to insert the jumper.  You can loosen and turn the distributor a little either way with or without the engine running.  But again, the engine should be at operating temperature for best result. 

It's possible that the outer ring on the damper has slipped, so you may not be getting a true reading.  It may take a little playing with the distributor setting to achieve an optimal position. 

[The Art Doctor]

Live and learn.  Hopefully it's ok, if not I'll be in the market.  I think all my fiddling might have set the computer a bit haywire. I pulled the battery cable and will let it set tonight and start over tomorrow. 

On the 8 degrees timing I think I may have a mark off because I got the same reading for both 1 and 4 the same.  Its probably very close right now.

[Fierofool]

Every time you kill power to the ECM, it has to relearn the sensors.  That means you must drive the car at road speeds for some distance at operating temperature.  The distributor isn't a sensor and there is no relearning associated directly with it.  It's a mechanical adjustment.

It can be a bit of a chore and even dangerous to disconnect battery terminals.  The negative is cramped in.  The tool used on the positive post can make contact with other vehicle parts.  If you want to clear trouble codes set in the ECM, disconnect the small tubular device that is just outside the battery case and is connected to the C500 wiring terminal near the negative terminal.  That's the ECM constant power.  It's a red wire, sometimes faded to orange or yellow. 

[GTRS Fiero]

Hmmm.  I think that one needs a new topic.

[The Art Doctor]

Ok, probably own worst enemy.   Plugged back in battery.  Took for long drive.  Re set timing with ALDL jumped properly.   I tried driving with it set at both 8 and 12 degrees and honestly didnt notice any seat of pants difference.  The idle rpm was definitely different at each setting.  Using the coil wire I got the timing finally dead on 10, double checked using 1 and 4 plug wires.  Runs like it did but without ALDL jumped idle is exactly 500 rpm over.   With jumper it is a bit higher than before around 1150.  I could probably loose the 100rpm if I readjust timing again a smidge but then it would not be even at 4 and 1.  It did the high idle thing when the plug blew out, took about 700 miles for it to come back down.  Slow learning computer I guess.  I'm going to stop messing with it and just drive.  I think one of my big errors was not hooking up timing light before removing the distributor and seeing what it looked like at the mark so I'd have a frame of reference.

[Raydar]

You actually can set the timing by ear, like in "the olden days". Advance it until it pings under load, then back it off until it doesn't.
It's how I set my 4.9. (I believe the timing ring has slipped. After setting it by ear, I hooked the timing light back up, just for grins. It "shows" 10-12 degrees more advance than the book calls for. When set to spec, using the light, it doesn't have enough power to pull a fat man from a donut shop.) 

[Raydar]

Hmmm.  I think that one needs a new topic.

Possibly right...

Admins?

[GTRS Fiero]

Hmmm.  I think that one needs a new topic.

Just a thought.

[The Art Doctor]

Ok I promise last post from me on this subject.   I went and put the original ICM back in to eliminate that variable, no change.  If the stumble returns I'll switch it back.  I tried to adjust timing for RPM and she fell flat.  I went back to the 10 degree setting by the light with the jumper in place, which position matches marks I made before pulling it, and it again pulls strong.  Idle is way too high at 1750 now but it runs as good as before. Will remove intake snorkel and check for vacuum leaks but do not expect to find any.  Going to have wait for computer to recalibrate.  At least its stable and not swinging.  And it's cold out so less chance of overheating in traffic. When the plug blew out it was this high at first.  It took a trip of over 1500 miles to drop half way then another 700 to drop last 250rpm.  Could take months at the rate I have been driving.  Sucks, but at least I have the oil spill finally under controll.

[GTRS Fiero]

So, the driveline vibration is back under moderate acceleration.  No nearly as bad, but there.  I can feel it in the steering wheel, and a bit in the car.  Just a bit, side to side.

[The Art Doctor]

Rebalance the tires?

[GTRS Fiero]

That occurred to me--especially as I was watching one rear wheel of a Jeep bouncing away, next to me.

[The Art Doctor]

When they are worn about half way a rebalance can bring back smoothness lost.  Also possible you threw a weight.