fast. too much 02 correction

[davekusa]

I've just about ripped all the hair out of my head. NEED HELP!!!

410 supercharged 96lb injectors. couple of problems.

1. Car starts and dies untill warmed up.

2. Set VE at 28 and A/F at 14:1 idle and O2 goes from 12:1 to 16:1 back and fourth. 27VE is too lean.

If anyone could show me the light it would be appreciated.
I called fast tech support and it was the blind leading the blind.
They told me that closed loop gain could be lowered to 3. I can't get it lower than 10.

I may just need a whole calibration file(Gct) If anyone can hook me up.

I've been playing with this thing for a week and have made no progress.

 

[wagon]

I'm not great with FAST, but I have learned a few things, so here goes.
First off, I think you are shooting for too lean at idle. My car likes about 12:1, if I want to keep it running. Most people can't get the car to idle well with closed loop, so shut that off. If you want to run closed loop later, you can try that, but at least for now, disable it until you get a decent idle, and you can see what the car likes for A/F, and then set your closed loop parameter to match that. Raise the idle up quite a bit, just to keep it running. Then at least you won't have to keep restarting it while trying to get a good tune. You will have all kinds of other issue interfering, like cranking fuel, startup fuel, and other things that will just mess up the fueling. Then, as you get it better, you can slowly bring the idle down.
Hope this helps. Good Luck.

Brian

 

[Ricky Trussell]

If the car cranks then dies you need more "afterstart enrichment". Look at that setting and start bumping it up in the temp area it cranks in. you can do this a couple times before you are out of that area. Just a starting point would be ...25% enrichment at 16* and taper to 0% at 110*.

If you run IAC you need make sure it is not REAL active at idle. If it is you need to open your TB blades. This would make the engine hunt because of reaction time.

Change your idle A/F ratio to 13.3 to 13.5 and turn the 02 off until you get it where the engine does not hunt.

You need to make sure your timing is where you want I run mine at 29 total at idle.

I would start the engine and select the six cells around where it idles in the VE table and start bumping them up until the hunting goes away.

Then post results.

 

[norbs]

Tricky thats very good advice. First of all its not going to run in closed loop cold. What you have to do is log the a/f fuel ratio when cold for the first minute of operation. IT should be about 12.5-13.0 max cold. Set the closed loop temp to about 150 degrees for now. make sure the closed loop step is set to 9 also, and if you want to idle warm set the low and high limits to about 900 rpm. Set the idle speed when cold to about 1300 rpm tapering off to 900 when warm.

If the car starts and dies you should add afterstart enrichment . Now you have to understand afterstart enrichment is enrichment based on only the first 30 seconds of operation, I have mine set like that anyway.

Warm up enrichment is basically for the first 5-10 minutes of running. SO you must make a comprimise betweeen the two.


On the data log , log the cts correction and the aft correction, and you will see the aft correction decay out quickly, but the warmup enrichment taper off slowly. Keep adding fuel to the afterstart until it idles cold, then watch the a/f ratio as it warms up. After 30secs or so, or when the afterstart is decayed out, then look at the warmup enrichment how much is being added, and keep adding there until the proper a/f is obainted.

First make sure your iac is about 10-20 when in park idleing hot, if its not adjust your throttle blade until it gets there. You can do this by using the throttle follower window and watching the circle move when from park to in gear.


Get some logs up that would be great,


norbs

 

[tonydee64]

This all leads me to another statemtent.... I thought I had fixed my problem but I didn't..as still get some smoke at idle and during throttle blips... Even if I take it out of closed loop and remove as much fuel as I can (the applicable cells are at 47 at idle) before it dies, it still smokes, not as much as it did... but it still smokes.. I think I found the problem after I came into the house and took a shower.. My throttle blades are only open at 10 during idle and you can definately see and smell the gas pouring out of my exhaust. If you read the FAST help it does make a statement that large duration cams and large exhaust can make the ECU think it is much leaner than reality at low RPMs. That has got to be my problem... I think tomorrow morning I am goung to open up the throttle blades a bit to get more air into the motor and then manually take out more fuel tpo get a leaner mixture. I guess the only question is.. how do I know how far to open up the throttle blades? Any ideas?

Not to highjack your thread,, but this may be your problem as well.

 

[Ricky Trussell]

THANKS Norm, been reading your post!

tonydee
What is your idle A/F ratio? Are you sure it is rich? Do you have any enrichment at idle? Are you able to meet your idle target?

Throttle follower should be set around 10 at idle. If the engine is not there when idling but above that set point open your throttle blades slowly until it comes down.

I would be more concerned about your enrichment setting more than your cell VE's if the smoke is when you give throttle.

 

[davekusa]

thank you all,

I can now see the forest through the trees.

I made adjustment to cts correction on the second log.
It may be the exhaust fumes but the car starts so good I have tear in my eye. You may or may not know how frustrating the past week had been trying to get this right.

Norbs, you should rewrite the manual for fast.

I don't know how to post logs on this message board????

Car seems a little fat at idle. I'm going to lean it out tomarrow and see how it runs.

 

[davekusa]

the next question:

Should I run in closed loop at idle or wait till about 2000 RPM?

It seens like is surges a bit 250 rpm. The 02 correction still seems to swing.

davekusa

 

[bobc455]

A surging idle might also be caused by too much idle timing. Just a thought.

-Bob Cunningham

 

[norbs]

Depending how much cam is in the car it might be hard to run a closed loop idle. Try making the a/f ratio very close on the a/f map between cells. Bring the A/f ratio rich until the idle stabilizes, you may have to idle at 13.0. Put the car in gear when you make all your idle adjustments, and make sure its hot. Try about 35 degrees timing around idle, and zero out the idle spark for now. Keep us updated



norb