First time calc.vet attempt, I have issues

[thunderstruck507]

So I set PE table 3618 to display in AFR but the ones on the table are what I would want, but the wideband reads leaner. Do I just reduce them until the wideband shows what I want it to be, or does this mean something is off somewhere else I should correct first?




I started looking at my idle tables. I think first thing tomorrow I need to unplug the IAC and set the tb screw. The car sometimes wants to drive itself with no throttle...but the guy who did my last tune apparently zeroed out the throttle cracker airflow table.

[thunderstruck507]

Set my throttle blade. Idle is pretty darn good except it still has issues rolling up to stop lights where it will idle fine for a couple seconds then fall too much and start fluctuating enough to stall. If you stab the throttle hard then let off you can be pretty sure it will die too.

Last couple starts it has stopped revving itself up and taking a while to fall into normal idle, it also no longer tries to drive itself down the road.

Back to the books. I guess the hard part is deciding which of the dozen or so parameters that effect idle it is I need to be working with.

[thunderstruck507]

Last couple tunes I have tried are much much much worse. The car won't stay running without throttle input, so I went back to my previous tune.

Now it does great everywhere except cold starts, it starts hunting when coming to stops right before the car gets fully stopped, and if I goose the throttle and let off. I keep trying different things with timing and the throttle cracker and either nothing changes or it gets worse. The car also often stumbles or dies when going from park to drive or reverse.

The reading I'm doing still hints that it could be something to do with the idle timing transitions between tables. Also I did notice on warm start up the idle AFR gets as lean as 16.8-17 which seems too lean to me and could be contributing.




Well hell, tried to go to a cruise in with some friends and with no changes to the car other than it cooling down, it started acting like crap again. Fired off and ran a couple seconds then died and from then on the rest of the night I had to 2 foot it to keep it running the rest of the night, even after warming up and driving 15 miles on the interstate. If I let off the throttle it dies. When letting off even before the RPMs drop all the way it sounds weak and quiet. Air fuel with the minimum throttle to keep it running at 5mph roll was 14.8-15.5 but kept flashing to 16s and low 17s too.

I'm pulling hair here. It's going to be really hard to fix the tune if the same tune runs this bad a couple hours later. I drove on this tune a dozen times or so this afternoon.

[joecar]

Anything above AFR 14.8 is too lean.

Did you also correct the MAF table...?

You might want to check the O2 sensors, in close loop are they switching sufficiently fast...?

Do you have long tube headers...?

[thunderstruck507]

I did correct the MAF table based on my last log.

O2 sensors were switching fine last time I was scanning. Yes I do have long tubes. I'm going to scan for codes tonight and try some logs to see if I can't pinpoint what the issue is, which might be difficult since it's intermittent.



After I look over everything mechanical I'm going to try logging cold start idle and saving that then logging warm idle and saving that so I have some things to look at.
If that doesn't give me something I can work with, I'm debating starting over from scratch at this point. Double checking IAC counts and adjusting the throttle blade, clean the MAF sensor, and then just reload the base tune I had and do VET all over.

I'm just confused why the car will be almost perfect minus some idle transition stuff, then after sitting a few hours would be virtually undriveable.

[thunderstruck507]

I reset the throttle blade so at warm idle I get IAC counts in the 70s.

Is it normal that my idle g*K/kPa are in the 55-60 range? A friend of mine seems to think that seems way high but he is basing his opinion on import car tuning. It seems to be idling with the MAF in the 1.2-1.5 lbs/min range now, when it was cold I had to hold the throttle to keep it running and it was flowing 1.8-2.0 lbs/min.

I still don't know why the car wouldn't stay running last night. Once it got warmed up tonight it seems back to the usual, rock solid idle until I blip it then it hunts a moment and settles.

I did 2 short logs, 1 with basic info and 1 with calc.vet pids turned on.

[joecar]

55-60 is on the high side of ok.

[thunderstruck507]

I cleaned the MAF sensor and looked over everything (o2 sensors, fuel pump, vacuum lines, battery connections, ground wires, etc), it all seems ok. I also marked the TB set screw so I can watch and make sure it's not backing itself out. I can't think of any other ideas which would make the car intermittently not want to stay running.

As long as that issue stays away I will start trying some things based on the above posted readings. I think I will start by logging a lot of idle running to see how accurate my VE table is in the 800 range then as per the reading copy the 800row into the 400 row and reduce it by ~10%.

I will also make sure the low end of my MAF scaling is also accurate and look over the timing settings for idle before proceeding with other tune changes since it looked like it was dipping into the teens rather than staying in the 20s.

[joecar]

Look at other things also:
- is coolant being consumed (check cold and hot levels in overflow reservoir every day);
- is compression good;
- is there oil in the intake manifold (pooled on floor);
- are you sure about exhaust leaks;
- do you get good spark at all plugs;
- do misfire counts register any significant counts.

[thunderstruck507]

Everything mechanical checked out.

I redid the low end maf scaling that my log didn't hit and that seems to have helped considerably. They were really bad low, I think under circumstances where airflow was dipping into the lower hertz ranges it was causing issues. I raised the values to be closer to the ones I logged.

It idles high on a warm start then finally drops to where it's set at 850rpm and idles great there. You can goose it a little and it does good catching itself, but goose it more and it surges then dies.

I tried copying stock tables for TC, TF, and IAC and reduced them 50% per a link above. With that tune the car idled high, but when it came down instead of idling at 850 it just flat out died.

So I reverted to my previous tune. Here is a log of that. Any suggestions on what to attack first on my next attempt to prevent the surging?