How to time cams for better gas mileage?

[NDB]

i'm pretty firm with the tires and i have a suspension stiffer than ever. my aerodynamic drag should possibly be lower also due to the ride height. i can't change the ignition timing on the L-jetronic. can you explain what the closed loop thing is with the NBO2? i've been running the Valvoline VR-1 20W-50 with a remote oil filter. also lined-in is a 180 degree thermostatic bypass to a massive oil cooler. i don't think my oil gets hot enough to create a large enough bypass through the cooler because after driving, i touch the cooler and the inlet is somewhat too hot to touch but the outlet is somewhat ambient. maybe its just really efficient? one thought was the oil thermostat is behind the radiator so its possibly getting false colder readings due to the ram air. so i was thinking of putting a plate in front of the oil thermostat to deflect the oncoming air. or maybe its just not working up to specs. i dont know, i need to mess with it some more.

do you know where i can get some headlight covers for this year alfa 83'?
i've look before back in the day with no luck.

[Tifosi]

You won't find headlight covers for the series 3 or 4, they just never made them and the tinwork around the lights is different enough to prevent any real bolt on of the older style lenses unless you want to fiddle around knocking tin or slathering bondo to close the gaps.

Closed loop is when the ECU gets it's signal from the O2 sensor and another signal from the TPS that tells it that you're not up on the gas or at idle. (there's a trigger signal from the TPS at idle and at 55 degrees & up throttle deflection. Stay between those points and the ECU will try to go into closed loop)

The ECU 'reads' the O2 signal and corrects the A/F mixture to stoich, which is 14.7:1. (supposedly the be all end all for efficiency, economy and emissions)

Fiddling around with the AFM 'may' cause the ECU to not be as efficient at maintaining closed loop, so it can be more harmful than benificial. (though the ECU does work over a pretty broad A/F range, so it may be possible to improve on things if you've got time to do a few dozen tanks of gas to prove one way or the other)


edited because my spelling is atrocious

[slyalfa]

does it have a timminging wheel on the crank? (front pully)
on the V6 the L-jet got the timming off the dizzy so if it was moved the timming would move too.
if you can not bump the timming try a lower grade of gas. if you do not ping the lower grade will give more power. so you should use less.
and it cost less.

one thing that might help some it to use newer type injectors. but you would have to convert to a rail.
the BMW guys say they get a few more MPG by puting in some newer ford type injectors that seem to mist up the gas more. they get them used off ebay. but I think they are Hi-Z the L-jet is Lo-Z
my guess is a peak-n-hold circuit will be fine with Hi-Z

[ghnl]

Motronic ('90-'94) has a crank sensor at the front pulley. L-jet ('82-'89) has two flywheel sensors. Note that 'adjusting' the distributor will have no effect on ignition timing. The ECU controls that (based on info from the flywheel sensors & the vacuum sensor). The distributor functions only as a 4-way switch.

[Joe Papa Sr]

My 87 gets low 20's.
Pretty bad for a 4 cyl. PLUS, no power.

Stiffer tires are the biggest bang for the buck.

[Joe Papa Sr]

Quote:

Originally Posted by ghnl Make sure the Manifold Pressure Sensor (measures intake vacuum) is functioning. It is located under the trim panel behind the right side seat. If it is faulty (they've been known to leak) or its hose is cracked & leaking the ECU (computer) won't know to advance the igniton timing under cruise conditions. That'll reduce fuel economy.

[NDB]

Awsome guys, thanks for all the information. It helps me out alot.

Tifosi, how long does it take for the ECU to go into closed loop when your between idle and 55 degrees and how does the TPS tell the ECU your above 55 degrees? I've checked the continuity of the connector on the throttle at idle and at full throttle and can hear a audibly quiet click at those points during my rigging.

Well, I'll keep you all updated on my mileage as I try different things. I fill up about every two or three days so i'll know pretty quick how these things effect my gas mileage. i'm hoping low to mid thirties, that should be good. you figure alot of modern cars now that have the "good gas mileage" are getting around that anyways. i guess the prius is at 48 so, thats sumwhat close.

[ghnl]

Quote:

Originally Posted by Joe Papa Sr Do you think that could be my source of this strange sound , like a "low whistle" coming from that part of the car, occasionally? (87 spider).

[ghnl]

Quote:

Originally Posted by NDB how long does it take for the ECU to go into closed loop...?

[NDB]

old enough where i've never changed it. car has 105,000 miles. who knows when it was changed. i've been meaning to change it. i just had the whole exhaust removed including the header. i was going to change it then but, wanted to get the car back together in a hurry. i'll probably end up changing it soon though because i need to repair a crack in my header thats feeding exhaust fumes into the cabin. i tried one of those quick repair paste things but it didnt do s@#$ and cracked right off. so i'll just end up welding up the crack. it doesnt help either that my car is so low the exhaust frequently scrapes the ground over some curbs or even minor speed bumps.

[NDB]

ok, i've filled up twice now. the first time, i was light on the throttle, staying around 3000 RPM for cruising, and pretty much driving like a semi-truck. With minor city driving, i barely got about 27 MPG. i was pretty unhappy. so after i filled up, i just decided to drive how i wanted and actually enjoy the engine. remember this is with some of the mods back off of the car. well, after shifting at higher rpms and cruising pretty much as fast or faster than the flow of traffic. which is about 3500-4000 RPM and 85+ miles per hour considering the speedo only goes to 85. with these conditions, i achieved 29 MPG. i thought i was going to get much less. something i did notice about the higher driving speeds is that my coolant temp stayed below 180*F. usually it hangs out at about 180-212. somewhere in that range. and also, i noticed my oil cooler was pretty hot at both ends. i need to put in some duckting to has some airflow hit it a little better. its behind the bumper in a horizontal position with a slight angle down at the rear. it does not block the radiator at all but it just doesnt seem like its getting the maximum airflow it can get. i'm going to go ahead and re-time my intake cam to open earlier and then soften up my AFM flapper door and do some other stuff to put some of the performance back into the engine. the difference in power is phenomenal. my idle will suffer a bit. makes it sound kinda like an older muscle car. when i had it in this condition before, i got asked numerous of times, "what do you have in that thing?" part of the unique sound is the exhaust. it has a full length header with a gutted cat, which i found out later after i had it taken apart(and it did pass smog), and a muffler which doesnt really sound too different whether its on or off.
i'll post again with my MPG after this stuff, its more fun anyways driving how i want.

[NDB]

p.s. any way to get the cam cover to stop leaking? its a new gasket and all but i still get oil leaking into the top of the spark plugs.

[Geezer]

NDB,

Nothing is better than a good old fashioned tune-up. Fill the tires and check that the front wheel bearings are not too tight. My '82 gets about 35mpg on the freeway.

BTW don't let the great gas milage of a hybred fool you. They get their best milage in stop & go traffic. On the open road their milage is crap.

FWIW During the '70's gas crunch is would advance the cam in small block Chevy's by 4 degrees with some success in better milage.

[NDB]

really, thats very interesting. i'm curious to see how my cam advancement helps or hurts my gas mileage in this car. here's what i've done so far, in the next post.

[NDB]

Ok, heres the intake system taken off


I've modified the throttle plate by smoothing out the leading and trailing edges. Also I removed half of the piece the throttle plate slides into, I don't know what you call it, and smoothed out the ends of the screws where they stick out. Also allowed it to open fully horizontal.



Here is the full length header


Here is the exhaust cam currently. It is already slightly retarded so this is where I'll leave it.


Top View


Here was my intake cam before I adjusted it. It's lined up correctly.


As you can see here, I marked these splines on the intake cam to where it was before I re-adjusted it to the correct point. I will just re-time it back to these marks.


Secured the nut with the special tool...


Re-aligned the Pico line


Now here is my intake cam timing marks, slightly advanced.


Now I'll adjust my AFM flappe door a little softer but not too soft because I still want to have somewhat of an idle. I marked the original position for easy adjustment back to stock.


I've put some RTV on the inside of the rubber intake tube because it's slighty cracked. Don't want any air leaks. So I'm just waiting for that to dry and then I'll put her all together and take her out for a spin to see how it does.