Alfa Romeo Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
I just replaced my dizzy cap and rotor on my 83 Spider. Then I thought I'd check the timing. Well I hooked up the timing light and checked the timing. My question is with the marks. My engine is hitting on the P mark vice the F like stated in the manual. Is this right? My MAP sensor is disconnected because of the whistle noise. Does this effect the timing slightly and cause it to be off? Also another question I have. What is normal operating Eng temp? And at what temp does the computer start to take over? open loop to closed loop. Many Thanks!!!!
 

·
Administrator
Joined
·
16,622 Posts
I assume the MAP sensor has a lot do with timing. That is its main function... There is info about setting the timing in the L-jet page (see my signature for a link). Turning the distributor will not 'adjust' the timing - the computer does that based on input from the flywheel sensors.

"Normal" operating temp will depend on the rating of the thermostat. I have a 180F T-stat in our '84 Spider - the gauge reads about, umm, 180 degrees!

The computer will go into closed loop whenever it gets a valid signal from the O2 sensor. Our models have the single wire sensors - they are heated only from exhaust gases. As the engine warms up and the sensor gets hot enough to work the computer will take over mixture control. Idling (even for a few minutes) will allow the O2 sensor to cool off enough that it'll revert to open loop until you start driving again. I think the computer does take engine temp into account to slightly richen the mixture during warm up.
 

·
Registered
Joined
·
1,960 Posts
MAP is quite critical to ignition timing. Repair leak, replace or sustitute. If you don't, you are basically driving your car with no advance. That is a real debit to performance, economy and poor igition.

TTFN Elio
 

·
Registered
Joined
·
219 Posts
Timing

Eric and All;

Correct me if I'm wrong but if one "matches" the Mark on the distributor to TDC and the point off the Water pump then they should be correct with the timing on the Alfa.

Also the ECU should "adjust" the timing and there really isn't any "timing" than one can do on L-Jet's.

Thanks, Steve
 

·
1966-2013
Joined
·
13,741 Posts
Eric and All;

Correct me if I'm wrong but if one "matches" the Mark on the distributor to TDC and the point off the Water pump then they should be correct with the timing on the Alfa.
With all things in working order, yes.

Also the ECU should "adjust" the timing and there really isn't any "timing" than one can do on L-Jet's.
Correct. Trying to adjust the dizzy to get more advance or retard will do nothing but mess things up.

The vac line on the back of the plenum under the brake booster hose goes back to the ICU and from there the ICU does all the adjustments based on crank position sensors and vacuum. (part of the reason there's such a broad contact blade on the proper L-jet dizzy rotor)

If correctly set at static on the 'P' mark, once the engine is fired and warmed up, the pointer should be at the 'F' mark (11 degrees advance) at 950 +/-50rpm idle speed.

Somewhere up in the rev range, it approaches a max of around 37-38 degrees advance. (what would be the 'M' mark on some earlier L-jet crank pullies, but was later dropped all together)
 
1 - 6 of 6 Posts
Top