ALFAGTV6.COM

Murray · Post by **Murray** » Thu Jun 09, 2005 2:57 pm

Guys I need your input.My 1986 GTV6 2.5L ignition is acting strangely - takes after its owner

Last week I set my static ignition advance at 8 deg BTDC using a timing light with the vacuum advance disconnected and plugged at the throttle port.My vacuum advance is new this year by the way.Today I hooked up the timing light to double check (I'm anal about these things )and the static was at 22 deg BTDC.What could have caused this shift ? I'm assuming its a problem with the nasty little E-ZL ignition controller.What do you suggest? Distributor was well bolted down by the way and is mechanically in good shape.

Alfisto Steve · Post by **Alfisto Steve** » Thu Jun 09, 2005 6:04 pm

This happened to me, but may not be your problem. I bought a bad running GTV6 some years ago and ignition timing was all over the place.

Turns out the aux drive pulley for oil pump and distributor had loose bolt and had a groove worn around dowel pin so gear would advance and retract on dowel pin.

I would pull R/H head timing belt cover and check aux shaft/gear for loose bolt.

Barry · Post by **Barry** » Thu Jun 09, 2005 8:17 pm

Id second that one Steve-An old problem ....

Murray · Post by **Murray** » Fri Jun 10, 2005 2:42 am

Ok guys I pulled the belt cover (I'd forgotten how much fun that is with everything connected and engine in car) and the bolt which fastens the distributor/oil pump pulley seems to be good and tight, although I can't see how you can torque it down anymore without spinning the pulley against the timing belt .Anyway the pulley is on there tightly.If I grab the distributor rotor and rotate it there is a little play maybe 5 deg.left and right but it seems to me that this is normal ? Next step ?

Alfisto Steve · Post by **Alfisto Steve** » Sat Jun 11, 2005 9:51 pm

Do you have V6 cam pulley tool (spanner) that you could hold aux shaft gear and check bolt for looseness/tightness? Do not use timing belt to hold gear while you check bolt bolt with a wrench. If bolt looks tight but will loosen without much effort loosen it slightly and try your distributor movement test again.

Maybe hard to verify with belt tension on gear. I found my bolt hand tight and since I was doing water pump/timing belt change I pulled gear off and saw problem.

Another thing to check is counterweights and springs for centrifigual advance in distributor. some movement as you indicated is normal but do weights stick or is a spring weak or broken so the don't snap back to neutral at idle?

As for how EZ ignition ECU can affect timing is beyond my level of knowledge.

Murray · Post by **Murray** » Sun Jun 12, 2005 12:44 pm

Steve I don't believe my 86 has centrifugal advance only vacumm.Thanks for the suggestion re cam pulley tool. Bozo here never thought of that one.The pulley is good and tight so I'll remove that from the equation.I know that the E-ZL is responsible for advance beyond the vacuum unit and it's the only culprit I can come up with .Any other thoughts ?

Alfisto Steve · Post by **Alfisto Steve** » Tue Jun 21, 2005 10:48 am

Your right as EZ-L ignition ECU system does work of old centrifugal advance counterweights.

Reale · Post by **Reale** » Tue Jun 21, 2005 11:55 am

Your 86 GTV6 should have a vacuum capsule, connected to the throttle body. This produces advance only at part throttle conditions. At large throttle openings, there is no additional vacuum introduced. As an example, on my car, with part throttle to take RPM above 4000, my advance with vacuum connected is 40 degrees. Without, it is 27 degrees. Please don't use these numbers as targets for your car, I only bring them up to illustrate how much advance the vacuum capsule can introduce. Definitely make sure that the vacuum line is disconnected for your timing measurements. BTW, the throttle switch should retard the spark 2 degrees at idle/no throttle condition, and put that 2 degrees back in the moment the throttle is opened.
Hope that helps,
Al

Alfisto Steve · Post by **Alfisto Steve** » Thu Jun 23, 2005 1:41 pm

The 86 does not use dual vacuum retard/advamce module like 81-82 models. It only has advance module.

Reale · Post by **Reale** » Thu Jun 23, 2005 4:46 pm

The 1986 GTV6 uses two separate advance systems. The EZ-L system controls advance based on RPM, and throttle switch (no throttle=retard 2 degrees). There is also input from a temp sensor, but the factory recommended disconnecting it.
For the transient throttle state, there is a vacuum capsule on the distributor. The vacuum line does NOT go to the plenum, but rather to a port in the plane of the throttle body. This produces vacuum at part throttle, which results in ignition advance. At large throttle openings, the vacuum is abolished, as is the advance.
I have found this setup on MULTIPLE GTV6 and Milano models in the 85-86 range. In switching over to an MSD timing computer, I made an exhaustive study of the stock ignition system, and can tell you these things with certainty.
-Al

SamW · Post by **SamW** » Fri Jun 24, 2005 3:17 am

Al, I am going to cross jump threads here, but what would be the best way to freeze the distributor so there is no vacuum or mechanical advance, only ECU/Spark box controlled advance? Could I weld the Vacuum advance module for no movement, then re-install?

Reale · Post by **Reale** » Fri Jun 24, 2005 3:37 am

I took apart a distributor and found that the Hall sensor mount pivots in response to vacuum. It is spring loaded. The easiest thing to do would be to simply disconnect the vacuum line. I also modified a distributor with a small bolt, that fixed the position of the Hall sensor. I know that with the line disconnected the position of the Hall sensor is good for about 30 degrees of electronic advance. Bear in mond that with the vacuum line connected you get 40 or more degrees in the part throttle condition. I did not test to see what the maximum advance could be based on a fixed position Hall sensor.

SamW · Post by **SamW** » Fri Jun 24, 2005 5:57 am

Disconnecting the line is easy enough, I will give that a try, if electronic advance is good for 30 dergees and static is set at 10 degrees, wouldn't that get you to the 40? I know that the vacuum will get you more, but I am installing and aftermarket ign control.

Side question, why do you need more advance at part throttle, I am pretty un familiar with the whole ignition advance theories.

Reale · Post by **Reale** » Fri Jun 24, 2005 6:30 am

I think the stock static timing is 2 degrees before TDC for the 2.5L and 7 for the 3.0.
There is a discussion about the part throttle ignition advance rationale here:
http://www.cdxautowiki.org/index.php?title=Spark_timing

There is NO performance advantage at WOT. I did dyno runs with it hooked up, and disconnected, with no peak HP/torque difference. I do think that it can improve drivability.

-Al

Greg Gordon · Post by **Greg Gordon** » Fri Jun 24, 2005 2:37 pm

Vacuum advance is for part throttle response and fuel economy. It has nothing to do with full throttle power.

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