I'm still fighting that #$&^*@* cold start irritation. Today I ran my latest BLM log thru the aldl to bin utility, then opened it in Tuner Pro to correct the checksum. So far so good, The Prominator accepted the bin with no problems, but then it didn't want to idle in O/L. I could hold the throttle open slightly (about 1400 rpms) and it would continue to run, but if I took my foot off, the engine would start to surge a few times then die. I drastically reduce the O/L AFR and Cold AFR vs VAC to the point where the AFR was about 10:1. You would think that I would be back to a rich idle right?....NOT! Still surging then dieing. I tried resetting the IAC counts back to the stock settings, and upped the BPW in the hopes that doing so would raise the idle enough to obtain a stable idle with less than spectaular results.

My VE tables ain't to far off, I getting 108-112 BLM readings while datalogging, but I wouldn't think that running the aldl to bin utility would lean the tables out enough to lean out the O/L AFR THAT far would it?

With all that out of the way, how low can you set the O/L AFR and not screw things up? Or is there something that I am not getting thru my thick head?

As always TIA!

 

What are the cam specs in the engine? (0.050 duration and lift).

RBob.

 

I'm not sure, it's the stocker she came with.

 

Try going back to a stock BIN. On a relatively stock motor there shouldn't be issues such as you are having. One item to always check for is a SES blink at key-on, engine-off. If you don't get that it isn't running off the main processor and the code in the Prominator (or EPROM if one is using that).

RBob.

 

So far the only thing that I have modified in the stock bin has been the BPW (136 down to 127.95), AFR vs Temp (leaned out), Cold AFR vs Vac (slightly leaned out since this one adds fuel depending on load), IAC counts (lowered only above 31C) and the VE tables (which I ran thru the aldl to bin program).

As for the SES blink at key-on, engine-off, it comes on and is steady.

After doing MUCH more reading and searching, I think I might need to lower my IAC counts from cold up to about 26 C in order to richen up the coldest part of the O/L (since it acts like a vacuum leak), and worry about the idle speed once I get the engine to idle without my help.

The bin I'm running right now is slightly rich, ie. a very small amount of hard to see black smoke for the first minute or so after starting cold, along with a pop or two in the pipes as it warms up, and BLM counts in the 108-112 range in C/L while driving. Sometimes I also hear a bit of popping in the pipes when decelerating.

The bin I am working on (the one that won't idle in the coldest part of O/L) is the same one, but I ran the BLM log that I recorded through the aldl to bin program.

If any one wants to take a look at it I will be glad to post it.

 

bump for ideas

 

IAC doesn't do quite what you think it does, in regards to rich/lean. Sure it can add air, but, that air changes either the RPM or the MAP, both of which are in the VE. It adds to RPM if the load doesn't change (like headlights, AC, transmission, OIL!!). It adds to MAP if the load does change (which is usually seen by the RPMs dropping and MAP increasing, then IAC opens to bring RPMs up, end result is a MAP change). It's almost the EXACT same thing as opening the throttle. Opening the throttle slowly doesn't make it rich or lean, it just lets in more air, which is sensed by MAP which immediately adds the required fuel.

Think of IAC as a way to get JUST the idle RPM correct. Not A/F.

Black smoke is a sign of VERY stinkin rich - like 30% or more too rich. Take a look at the MAP and RPM during the black smoke time, and see if it's in an area that hasn't yet been reached in your VE tuning. Also, get your BLMs above 120 before digging into cold startup/warmup. I think many ECU's don't use lower BLMs than 128 until closed loop is reached. Target AFR only works if VE is correct.

 

That helps quite a bit.

Now can I bend your ear once again please?

The only time that I can see ANY black smoke is during the first minute or so of O/L. The smell of the exhaust is only the slightest bit rich in C/L at idle. Don't know if that helps......but ya never know.

Like I had posted above, after running my current bin thru the aldl to bin program, when cold, The engine won't idle in O/L. However, I can hold the throttle open slightly (about 1400 rpms) and it would continue to run, but if I took my foot off, the engine would start to surge a few times then die. I drastically reduce the O/L AFR and Cold AFR vs VAC to the point where the AFR was about 10:1. You would think that I would be back to a rich idle right?....NOT! Still surging then dieing.

Do you thing that the aldl to bin program lowered the VE tables to the point that the idle is to lean for the O/L AFR and Cold AFR vs VAC to have an effect in O/L?

Unfortunatly, I did not try to reload the bin after the engine warmed up to see what happens. I think that will be Friday's experiement after work, along with a little data logging.

Also I don't know if this is related or a possible mechanical problem. During O/L startup my idle speed is low (700 rpms or so). As the engine warms up, the idle speed increases (up to 1100) in neutral. Sometimes after the engine completely up to temp, the idle will drop down to the command idle speed of 750 rpms after a minute or so. Once again I'm not sure what is causing this.

I think that as a last resort, I will reload the stock bin (waaaaaaay rich) and readjust the BPW, then do a datalog to see what happens.