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Discussion Starter #1
Does anyone have a stock spark map for the 3.0l smec/sbec? Is this available somewhere? Also Is there a speed related spark map in the cal? It almost feels like there is. Power seems to drop off after about 60mph it even sounds a little different. does anyone else experience this drop off or is it a problem specific to my engine or even just aerodynamics?

On an unrelated note lately It seems like the van pulls harder at about 75% throttle than at WOT. Does this mean my base fuel pressure is off?
 

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Can't speak to the spark map.
As for 75% versus wot, this could be caused by a difference in wot versus part throttle maps. It's almost certainly engineered to run leaner on part throttle than foot to the floor.
 

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My 95 lebaron GTC pulls hard all the way thru to the rev limiter. the TQ curve of a 3.0 is very flat. so there is plenty for pull till about 5200 RPM. I think i would look into the throttle pos sensor to see if it is reading correctly.
 

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Discussion Starter #5
My 95 lebaron GTC pulls hard all the way thru to the rev limiter. the TQ curve of a 3.0 is very flat. so there is plenty for pull till about 5200 RPM. I think i would look into the throttle pos sensor to see if it is reading correctly.
Today 03:50 AM
It's not really a certain RPM range its more like when I get up to speed. First gear pulls hard like it should but second and third it seems to lag a little.
I am using a TPS from a 3rd gen caravan though and I had to splice on a different connector to make it work so I guess i'll pick up an older one when I go to the junkyard next week.

Another thought I had was that maybe Chrysler leaned out the fuel map at highway speed to improve mileage?

Has your fuel filter been replaced ? It could be restricted.
SpeedyEd
Today 04:08 AM
I changed the filter about 20k ago. I don't have a fuel pressure gauge or anything I was just thinking it was fuel pressure because from what I understand the computer is in open loop and using a preset injector pulsewidth at wot but at 75% it would be in closed loop and getting extra fuel.

I appreciate your guys' ideas and input thank you!
 

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3.0 isnt exactly steller high in the rev range. keep that in mind


here is a stock spark map put together as best they could



not sure what you plan on doing with it?

is your base timing set to 15*?



i wouldnt blame fuel pressure until you check it. Unless you have a wideband, its hard to tell if your running pig rich at 60mph WOT. I know from experience that pig rich causes misfires at 4000rpms and wont let you go any further. but i was running RICH as snot.
 

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uggg i forget who exactly it was. Someone on TM. They made it fro brent FOREVER ago to help him with his ms. It has stock timing and then it goes into boost but that was just a guess on what it should be. the 0-100kpa values "should be" correct.

I based my timing table off of that (actually it think im running a little more or less ) and i did well. (for the cruising part that is)

my car always performed very well when it was NA using timing very similar to that table. responsive and pulled hard for what it was.
 

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OK, well here's what's in the actual 3.0 cal from 1989. The '90/91 is basically the same. But, the '92 plus are different being that the cal data is 3D, not 2D.

The final advance is the MAP adv (either WOT or PT depending on throttle pos) + RPM adv. There are also min/max limits that aren't shown here.

You can see that WOT has significantly less timing than PT operation. And, I've never understood the big 'dip' in the RPM timing curve.
 

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idk how to look at those tables lol

the dip is believed to be for towing. you can give it lots of throttle and not go anywhere. running lots of timing and reving slowly is a bad idea and in theory will cause some ping to happen but the 3.0 dosnt seem to detonate while in stock form but ive only experienced a light p body that can lug its self in 5th at any speed.
 

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Discussion Starter #11
So it should in theory pull harder at part throttle then? I mainly wanted the stock map just because Im curious but it will help to have something to base my ms tune off of when I finally buy it.

Here is something interesting. I unplugged the speed sensor and now the van doesn't jerk when I let off the throttle with my TC lockup switch on. I think this can only mean one of two things. Either spark advance is indeed dependant on vehicle speed or the ECU is in some kind of limp mode where spark is retarded.
 

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no no no

here is a table that i used in the past (dosnt mean its spot on to stock but its what i drive on and it works well)

100kpa is atmospheric pressure in my area. 0kpa is no air and 155kpa is 8psi of boost

Usually i cruise at 40-45kpa around town (just to give you an idea)




AS load increases, timing decreases. As rpm increases, timing increases. you can see the trend in the table. the biggest timing value should be at max rpm and lowest load, while the lowest rpm with the highest load will see the least amount of timing advance.

So no part throttle will not pull harder than full throttle, not even close (unless something is not functioning as it should!) *keep in mind this is with megasquirt but the values in the table can be used with any engine management and even on the stock ecu if someone finds a way to copy them over*


33 degrees at 3500rpm pulls twice as hard as 41* at 3500rpm simply because the 33* is at 100kpa and 41 is at 60kpa

now if i had a way to log horsepower (or a dyno), i might find that i get a horsepower increase at 100kpa x 3500rpms by bringing timing from 33 to 41, but i would also find that i can raise the timing at 60kpa even higher. You always run more timing at light loads with low speed air charges.


as long as your sensors (coolant temp, tps, o2) are in working order, you should not have to worry about your timing map. something is wrong if full throttle feels sluggish.
 

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OK, well here's what's in the actual 3.0 cal from 1989. The '90/91 is basically the same. But, the '92 plus are different being that the cal data is 3D, not 2D.

The final advance is the MAP adv (either WOT or PT depending on throttle pos) + RPM adv. There are also min/max limits that aren't shown here.

You can see that WOT has significantly less timing than PT operation. And, I've never understood the big 'dip' in the RPM timing curve.
Hey, I have been crawling google looking for timing information and ended up using the maps you posted to excel spreadsheet a spark map, then copied that and made another one with differences I have noticed video recording a DRBII scanner in a 1994 SBEC II. Then working on a custom one for experimenting.

I remembered something form many years ago that Ed Kelly and Mike Mulhern did while testing.

The test here is adding 3 degrees of base timing (across the board by turning the distributor to offset the signal). It was a common belief before this time that adding 2-4 degrees of timing would gain power and there was much argument about needing to run higher octane fuel. Well I needed higher octane fuel to tow (and I still needed to turn back timing when pulling ~3000# with a manual transmission) but my tow zone was below the dip because I was always lugging.

Anyways, the HP gain here from adding 3 degrees starts the moment you hit the dip in the OEM table (and this dip still sorta exists in 1994 but everything is less extreme) HP goes up. Notice, no gains below the timing dip, which means timing is already optimum there.

Now going to use this info for the experimental map :hello2: This is why I run stock base timing on my turbo holset 3.0, because I didn't want to hurt things just to get the top end gains. Betting we could add more timing up top with your cals or MS since you are not forced to increase timing across the map.
 
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