I tryied to mod my bin for the first time toady. Im just playing around, so dont hate me if I post something really stupid :) hehe
This is for my hot camed 1991 TPI.

I took away alot of spark advance in the 1000/1200 rpm @ 50-80 Kpa area. Stock my car has about 35degres of advance at 1000rpm @ 50Kpa.
The modyfied bin has 20degres @ 1000rpm @ 50 kpa.
I did this to get rid of strange knocks at idle.
I also bumped up my idel speed to 900rpm.

Is this going to make the car weaker at idle, so I must also bump up the minimal IDLE setting?
After I did this I noticed that the idle is hunting a bit. And my low speed ( of idle ) crusing is "jumpy".
Im just learing. And YES im going to have a pro do this soon.
At least my knocks disapeard.

Heheh

 

I needed more advance than stock to get my car idling. I hooked up a vacuum guage and turned my distributor until I got the best vacuum. Then, I reset my distributor and burned the new advance into the prom.

To get a cammed car idling right, You'll have to juggle fueling, timing, commanded idle speeds, and throttle stop. It only took me a few burns to get the idle nice, but I've got MAF.

 

my car idle good with the stock setting. Change that back and start over?
I hade to screw the idle screw alot to make the car idle like it did before.
Going to chagen this back.

 

Patience is the word of the day when tuning. Before messing with timing you have to log a bunch of data and get your fuel trims (aka block learns) adjusted properly. For a '91, you do this via the VE tables. After that's taken care of, then you mess with timing. Change a couple of degrees at a time and not just in one place. The idea is to have a smooooth timing map. Take a look at the factory values and how the various cells relate to one another.

Regarding the "idle screw"...That's not for idle speed. That adjusts the air flow past the throttle blades when they're closed. That adjustment in turn affects the IAC counts (btw, the IAC valve controls the idle speed in accordance to what's programmed in the ECM). What you've likely done is adjusted the screw so far that you've maxed out the ability of the IAC valve to compensate...hence the hunting idle. You need to go back and adjust for minimum idle air. The "how to" is in the Factory Service manual or do a search since it seems to come up every other month.

FWIW, How much data to log and analyze? I'm looking at a basic log I did today to examine some fuel map updates I made. It has >47,000 data points over the course of a 20 minute drive and this is one of my smaller logs. Hence the reason you need a good spreadsheet tool like Excel to sort the data into something useful. Just looking at a few numbers flickering on a screen and then making adjustments is an invitation for bad things to happen.

 

I understand..

But do you agree that my low idle spark advance is cousing the idle to "hunt"? I dident touch the idle screw before or after i did the idle spark advacne tabel.

And how do you export and read logs in excell.
Im using datamaster.

THanks

 

It sounds like the hunting idle is in fact due to your timing map changes. Reflash to stock maps and then adjust your VE tables as required based on logged data

I use OBD-2 and AutoTap for scanning, so I can't answer conclusively about TTS Datamaster. I would guess that you save your log file as a text file or comma delimited file (*.csv). Excel will import either of those file types and then you can manipulate the data from there.

 

im just curios if im thinking right..

I made alot of scaning runs.

I get some knocks and spark retard @ 1400rpm - 1800rpm, crusing speed, @ 40kpa - 60 kpa. Going abow 1800rpm, no spark retard.
My spark advance tabel is pretty agressive there in that area.
Is it ok to lower the spark advance there, around 2 degrees, and then "smooth" the scale furter up in the Kpa scale? Burn a chip and then se how it reacts?
Is that the way?

 

could a to lean condition also make the car hunt for idle at cold starts?

 

You need to quit worrying about the timing and fix the idle and part throttle FUEL MAP FIRST. Once you get the fuel map corrected, you may find the engine runs fine with the stock timing map.

What is your block learn? Probably in the 130s. You need to get it below 128, and in general around 124. Once you've corrected that, then figure out how much timing it likes best at idle. After that, move on to part throttle timing. If you have knock, how much timing is it pulling? If it's pulling 4*, then start by pulling 2* since the ECM will sometimes "overshoot" the amount of retard needed. Still knock? Pull another 2*. Each time, the timing map needs to be smoothed over several cells and load ranges. Once part throttle is complete, then you move on to WOT with a wide band o2 sensor.

It can be agonizing. Everybody wants to be done after a single chip or flash. Unfortunately, the first time you tackle something like this, it can take dozens of chips before you get it right. Of course once you get it figured out, things come much easier the next time around. Like most things, it boils down to experience.

:cheers:

 

the blms are between 128 and 132.

 

Didi I just click on Scan and Tune?

 

You need to go in and look at where the BLM averages fall across the VE tables. Next go in and tweak the VE values so that your BLM averages are 124-128. FWIW, you'll always see a few spurious +128 points in the data, hence the reason to look at averages using Excel.

After that is done, then start addressing timing.

 

Again, you will have to juggle many factors. Spark and fuel are related. Your stock spark and fuel will not be right for your cammed motor. The minimum idle procedure outlined in the manual is for a stock motor. It does not apply to yours.

Regarding fuel and timing. Your cammed MAP motor will PROBABLY be too rich at idle because of less idle vacuum. Once you get your fuel close, attack timing like I outlined - you will PROBABLY need more timing in your true idle area - timing changes will affect your idle and fuel - they work together.

As far as throttle stop, IAC, and commanded idle, you'll need to crank open the throttle stop to keep this cammed motor running and command a higher idle in the programming. Once fuel and spark are close, you can fine tune the opening and commanded idle. I like to have 0 IAC opening idling in gear with no accessories on - that means the throttle stop is the only thing controling the idle at that point. That way, when you turn on your A/C and lights, your cammed motor that doesn't like that low rpm load can use the full ability of the IAC to keep it alive.

Remeber, everything you change WILL affect something else.