OK, so I am back at the PROM stuff after a brief reprieve. Got some good data logs and something has to be done about my idle. I have 17 inHg at 800 rpm. My minimum air is set just a tad bit to low so IAC counts go to zero at about 800 in park, and desired idle speed is 750 RPMs so the system really isn't working in harmony. After a 10 minute drive, she stalled on me and this appears to be the problem area (In drive, she idles at 730 but my P/N offset is 100RPM so I should actually be in the ballpark of 600).

What would you do? It ain't a big deal, but just wanted some of your opinions. Readjusting the min air ain't a big deal, but my TPS screws are kinda (read very) stripped, so it makes it a pain in the bum when I go back and redo that. -Matt-

 

I won't ask why someone would mess with the idle air algorithm...so tap the idle air screw hole, put in a helicoil and do it manually is the easy route. Of course this won't help with the cold idle will it.

 

Fix it so that the IAC can control the idle. If you up the idle in the prom and it gets icy this winter, your car will start spinning the tires without even touching the gas. Plus the car won't die anymore when you come to a stop. You know that's the right way to do it!!! :) :) :)


(But in the past with my '85 I have tried to 'fix' things in the chip rather than open the hood and do it right.... so it's up to you!!!)

 

There you go saving my life-I totally forgot about that! This is going to be my only vehicle this winter, and the Farmer's Almanac says it's gonna be bad. :eek: -Matt-

 

Like I said above.... I have tried taking shortcuts before!!! last winter this happened in my '85 coming home from work. The day started out in the 40's, but a bad storm came through with drizzle and 20 degree weather. The roads were completely covered in ice. My 4 mile drive home took almost half an hour. I would be at a light, let off the brake, and the car would just slide sideways spinning the rear tires. I would hit the brake, and try again! It sucked. In icy weather, low idle is your friend!!!

 

At warm idle, I believe spark is controlled by the "closed tps spark advance" (or some such name) table in TC $8D - NOT the main spark table. But note that "closed TPS" table is Total Advance, where the others are in relative advance.

Try adjusting the idle spark there for cold weather driving. You might also add a few IAC steps at idle so the stall saver has some room to maneuver - I think mine idles at like 5 or 10 steps warm, and has no trouble going down to 600 RPM.

If that doesn't help, the latest versions of $8D have some new tables for the "stall saver" feature, but I haven't looked at them yet - I haven't played with the MAT compensation tables yet, either, and they may have some bearing on cold weather operation.

Work with the simple stuff first - air, fuel, spark or earth, fire, and water - something like that.

drj

EDIT: - Whoops - I was thinking idle spark, you are thinking idle air -

Just re-read the first post - if your IAC steps are already at 0 you have too much butterfly opening at the minimum stop. You need to cut that down first so the IAC can go back into its PID function. If you can't move the stop screw it's likely you can bend the stop arm a little to get some adjustment.

If you can't move the TPS to get min voltage back in spec why not just add some small resistors to the TPS curcuit? It's just a potentiometer looking for 0-5 v. You must have run into Kierkoff's (sp?) Law by now - or one of your EE friends has. Better yet, add a muli-turn ceramic pot to the circuit so you can set the voltage in the future without moving the TPS body - you'll have to work out the values, I never had to do it.

HTH


[Modified by DOCTOR J, 1:15 AM 12/5/2001]

 

Note to 65Z01:

If you put a lumpy cam in, especially with a MAP system, the stock idle algorithms don't work very well. Generally a larger cam needs changes in the spark, fuel, and IAC tables to become liveable - especially if you are going to be out in the snow like Matt.

drj