Had a recent problem with TPS reading higher then it really was which caused the engine to run way richer then necessary. Once I got that fixed I went back to tuning but it seemed like my idle quality was a lot lower then before winter. I used to idle at 45kpa @ 800-850 (25* BTDC) in park with about 5 IAC steps before winter. Then after installing the rebuilt trans I would idle at about 55kpa @ 850-900, 10 IAC steps. I tried varying the timing to clean it up but the kpa never got lower or higher. I tried changing o2 constants with no change. After reviewing all my logs (no driving since re-installing the trans) it showed my O2 cross counts were low and at times it would stay at a certain number for several frames. So I figured the O2 was probably bad. I bought a new heated O2 sensor (F*rd application, what I was using before). I started the engine and it immeadiately was idling at a higher RPM then before, IAC steps were 0. Once warmed up the BLMs shot up to 150 but the engine wanted to idle at about 1400 rpm. So I figured this was as good as time as any to try SAUJP V4. I wanted to use the base V4 bin with as little edits as possible to see if I goofed something up with my current bin. So I changed the inj constant, cylinder vol, spark table, and the Loop Open AFR vs. temp table. I also backed the timing off to 23* at idle in the main and closed throttle tables. Started the car back up and it idle great. The map values were about 30kpa but the RPM was still high once warmed it was idling at about 1400 rpm. The O2 cross counts looked good and the BLMs were about 116. I backed off the TB screw and the idle started coming down. With the screw backed all the way off the RPM was about 1050-1100@30kpa. To make a long story short I tuned things just making changes to the spark and VE tables. I ended up with 20* timing@idle, 30-32kpa and the BLMs were 122-128 kpa. The problem is the TB screw is all the backed off and the idle is about 1050 in park. Putting the trans in gear it settles to the correct commanded 800 rpm +/- 50@42kpa IAC at 0 steps. I'm wondering why I can't get the idle speed lower in park? I changed as little as necessary in the SAUJP V4 bin. I am using the expanded upper VE table though. I changed nothing regarding the open loop idle settings and my commanded idle RPM is 800. Also while tuning the VE table and running from RPM range idle to 3000 rpms in park over 1400 rpms I was hitting 20 kpa and when letting off the throttle quickly sometimes I would see the kpa hit 13-18 kpa. I'm not complaining much the engine is running a lot stronger at idle then it ever did so I was probably tuning with an O2 sensor that was going bad from the beginning. It just seems my map values are close to a stock TPI values whereas most with aftermarket cams seem to have 10-15 lower map readings. The map sensor itself is located near the FPR for the HSR using rubber connections with a hard plastic tube about 6" long. The only other thing is I get a lot of knock counts at idle due to the valvetrain making more noise but it goes away once the engine is off idle. I don't think that has any effect on the map though. Sorry for the novel. Any thoughts on the high idle? Other then maybe lowering the timing more?

 

I also have just gone through this with my idle.
For some reason, this spring and now, my idle (not in gear is up 200-300 RPM) is around 1150 RPM.
In gear idle is right at 800-850, same as before but I did have to reduce the mechanical setting when not in gear. Just did that today but I have not touched that in two years, Why now???
My timing is 26-28 at idle cuz my Sportsman heads just seem to like it there.
these heads need allot of timing as I'm finding out.
Moving timing has not changed my idle so I don't think it will help you either but worth a try to see if you can stop the knocks at idle.
Maybe we are finally getting real gas for our money?

I don't remember exactly what parameters can change idle for not in gear. Could be an IAC parameter somewhere.

 

I don't see anything that would cause this right off hand. However I did remove the throttlebody and found the IAC housing screws somewhat loose. Tightened those up and reinstalled. That seemed to help somewhat. But still the car wants to idle at a steady 1050 rpm in park and 800 in gear. Which before 800 was just barely stable. Now it is rock steady and almost sounds too high. With the way the car is running now I could probably idle at about 750 in gear or maybe even less. The only changes I could make to timing would be to lower the idle timing which is 20* now. I need to tame the IAC down. I went for a drive last night and when I pulled the car in the garage I put the car in gear and was up around 1300 rpms (was doing 40+ seconds before). Once the IAC steps went to zero the engine settled to 1050 again. I need to research why the max IAC steps in drive would be set to 231. It seems like when my IAC steps would climb during the drive it would affect the BLMs too much past 60 steps. I am also wondering if the O2 constants may be a tad rich for my present combination. The idle has a hint of richness but not as strong as a smell before the new O2. I just don't get it that there is such a huge change in behavior. But the car runs so much better then it ever has even when I disconnect the EST bypass to check the base timing (which is 8 on car and in eprom) the engine is running fairly steady at about 800 rpm.

 

I believe I located my problem.
After chasing possible vacuum leaks and tightening anything that could let air in,
I realized I never checked the PCV valve.
I installed a new one tonight and the idle dropped down lower than I originally had it.
Looks like the PCV spring was getting weak and was passing more air than previously.
The PCV valve allows air from the crankcase back in behind the throttle blades. An unseen, but controlled air leak.
Might want to do the same if your valve is old.
Jp

 

My PCV isn't old but something else I can check. I had to pull the transmission as the shop that rebuilt it didn't get something right. In the mean time I pulled the intake because the idle was changing as I sprayed carb cleaner at the base of the intake. I found the PCV hose loose on the fitting under the HSR plenum and found the inner part of the base to plenum gaskets broken and missing on both sides. I don't know what happen to that part of the gasket (I can only assume it got swallowed by the engine). I am also replacing the injector O-ring gaskets just in case. Hopefully that will fix any leaks I might have had.

 

i just went through this last night try changing your iac mine would start and run fine but when i would do a hot restart it would shoot the idle up to 1400rpm and would not come down for nothing also check the tv cable for the trany it might have gotten stuck when you put the new trany in
just my 2cents

 

Good idea on the TV cable.
I have the little spring thingy on there but I do think I popped a notch or two when I tromped on it last week. Lately I seem to running richer than previously as well. Maybe I'm not loading the TV as much as I was before.
I can usually see that on the BLMs pretty quick when it happens. Been playing with my spark table so much lately I'm not sure if the BLM was SA related or not. Back to the start again I think and reburn my tune from square one and try to find my happy place again.