Re-check your ignition timing... it should be @ 12 degrees BTDC with the two wires unplugged.

I don't think the "instant" jump is a problem. Mine does the exact same thing. There is no "advance mechanism" in the diz, the timing is controlled by the ECM.

Either it was timed wrong from the beginning... that is, when you timed it, it either wasn't warmed up, or the idle was set wrong... or... any number of reasons I guess.

I know you had some trouble getting the diz set correctly at first. Maybe there was some error made ?

In any event, set it to 12 BTDC at idle, and yes, you will see the mark jump WAY to the left when you come off idle.

OR: that new balancer you put on has slipped ???

As for the idle adjustment: I'm wondering how the MECHANICAL stop on the throttle body is adjusted ? Did you change it ? Is the paint still on the screw ?

If the mechanical stop is set too wide, you may not see a big change with the idle adjustment screw on the back of the TB . OR, maybe there is something blocking the idle bypass circuit ??

Try setting the timing back to 12 BTDC, and re-adjusting the idle . Don't worry about that "jump" when coming off idle. It's normal.

^+1 Don't worry about the jump. It's supposed to do that. The timing will always rev back to your base timing you set it at. So if your base timing is 12 degrees with the ECU advance disconnected, when you plug it back and hit it with the timing light again you'll notice the timing change because of the ECU advance.
Depending on what the ECU picks up will determine how much advance to get a better burn during idle. Make sense?

Sounds like a dist that's a tooth off (or a cam that drives the dist is a tooth off) -- like everything is working perfectly, just 20* late!

Bob, have you set the TPS and throttle plates? If not, do so. The procedure is in the Helm.

Michael

Michael, I didn't see anything about setting the Throttle position sensor. Only how to test it to see if itÆs working correctly. Can you elaborate?

And what dose ôBTDCö stand for?

If the EMC was not advancing the distributor properly when I originally set up the ignition timing, could that explain why the timing is off now?

And nope the balancer didnÆt slip, I checked TDC with a new little tool I got. It screws into the spark plug hole and touches the piston when it gets to the top.

And yes the throttle plate is shutting all the way. So the idle adjustment screw should be working. But with as much retard as it had that might be affecting it too much for me to notice the idle adjustment.

Before Top Dead Center

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

AH <img src="/forums/images/graemlins/wink.gif" alt="" />

Ok I played with the ignition timing and I think that was my problem, sort of.

I obviously got the timing wrong the first time, or something happened to make the timing off. Anyway it seams to be right now. I have lots of power, and it idles ok.

But I still have an under lying problem. It seams to idle fine but when youÆre driving it and you let off the throttle and you push in the clutch the RPM bounces from 1000 to 1500 RPM. Like itÆs advancing the engine, then back, then advancing, exc.

So if it is the ECM advancing the ignition timing, what physically dose the computer take readings off of to decide that it needs to be advanced? Cuz that has to be the problem.

Michael, I didn't see anything about setting the Throttle position sensor. Only how to test it to see if itÆs working correctly. Can you elaborate?

The adustment involves gapping open the throttle plates a hair (.020?) and making sure the TPS is switching at the right point. That is why there is adjustment in the two screws that hold the TPS to the TB. This is in addition to testing between the three pins to make sure they are open/closed at the right time.

And yes the throttle plate is shutting all the way. So the idle adjustment screw should be working. But with as much retard as it had that might be affecting it too much for me to notice the idle adjustment.

The throttle plates have a stop. The idle screw is an air bypass orifice. Which screw are you changing? It should be the large one on the back side of the TB. Not the one that physically moves the throttle plates.

I am wondering if the TPS or the plates are misadjusted. It could give you the wonky idle thing you are describing. The TPS gives you idle, open and WOT. If it thinks it is still open when you have your foot off the gas, it will act funny.

I would help you more, but I don't have my books with me right now.

Michael