Finally got everything completed and fired the car up last night only to find out that the Eagle 6 inch H-beam rods were hitting the stock windage tray. Dropped the pan and got that fixed and everything seems to be ok. Now that the car is running without any major problems, I want to start getting the drivability squared away. The computer was tuned by Ion, just based on the cam specs and head flow numbers. The car runs extremely rich at idle and sometimes doesn't hold an idle. Also it sounds like a gremlin is holding on to the Borla and beating it with a broom stick, lol. As I drove it around, it seemed to run better and better, but still had the richness problem (burning my eyes rich). I tried to get the fuel pressure, but my brothers guage was boogered up for some reason so I couldn't get an accurate reading. My question finally is, should I keep driving it for a certain amount of time to let the computer "learn", or do I need to collect some good numbers (fuel pressure, air/fuel, etc. and get the computer tuned again? Sorry for the novel and any info is appreciated.

Thanks,
Anthony

 

The computer will learn surprisingly fast. If you hold an idle for more than 30 sec.. the idle fueling should be fully adjusted. Problem with a cam however is that valve overlap will always mess with the O2 sensors and you will always run rich. Overlap tends to send unburnt charge of air/fuel down to the O2s. Since the fuel calculation is supposed to account for that charge that isnt burnt, the computer believes the extra O2 in the exhaust is caused from a lean condition and therefore just adds fuel to correct the precieved problem. Naturally running no cats doesnt help the situation either.

The only real solution which is more of a temporary fix(that is until someone comes up with a better solution) is to run PE mode at idle. Only PE mode can be manipulated in closed loop therefore you can cut as much fuel as youd like... unfortunately its really a test and tune sort of deal and will most likely take several attempts to get right. Also, you MUST have a datalogger to monitor the O2 sensors so you can make the needed adjustments.

 

Would it be best to just drive it until it's broken in (approx. 500 mi.) and see where I stand with the car as far as what it has "learned" and what I need to get tuned?

As far as good logging software, I have AutoTap with the GM Enhanced parameters that I can use to log real time numbers. Would that be sufficient for collecting data, or is there other software that would be better suited for tuning purposes?

Thanks,
Anthony

 

I would drive it for a while until the engine is fully broken in, also make sure your rockers are adjusted correctly as this will also influence your "driveability".

As for the rich condition, you will have to live with some of it. I say the same thing to people many times - you can't expect your car to smell clean if you got rid of the cats. You can lean it out to the point where it will not smell rich anymore, but this is not good for the engine and will cause problems in colder temperatures.

Put a high flow cat on it or two and it will get MUCH better.

Also, replace your o2 sensors with some new AC Delco ones if they aren't relatively new. (20K miles or less)

 

Have you ever used the idle PE method to cure idle richness? My O2 readings hang in the low 100s which worries me sometimes however I get no KR and it run so much better this way its unbelieveable.

 

I've done that before, yes, but I preffer to only do it on a dyno so I can check the air fuel ratio.

My car runs speed density right now and once I do my M6 swap, I'll also convert to a MAF PCM, but I plan to keep it speed density. I like tuning SD much more than messing with the MAF/PE tables. (for part throttle fueling purposes)

 

I didnt think you could trust a wideband at idle because the valve overlap throws off the readings.

Also, are you saying SD doesnt use PE tables?

 

It does use the PE tables, but I tune the VE tables.

When I tune part throttle, I also watch the BLMs, but either way, if the wideband sensor is influenced by raw fuel dumped from overlap, your o2s will be influenced too since the wideband probe goes pretty much all the way in to the o2. (depends on the dyno too)

If I have a laser themometer handy, I also check the header temperature between the tunes. If it's too lean, it will go up. (you might even smell it burning or see them glowing if it goes WAY lean)

FWIW, I'd rather use a cat (and lose a few hp) than lean it out to the point where it doesn't smell like gas at all. A little extra fuel helps keeping the chambers cooler while extra heat reduces engine life.

Earlier fan kick on temperatures (cooler engine) will also cause it to run a little richer.

 

I'll check the rockers and adjust those to make sure with the car running this time. I do need to replace the O2's because they have been on there a while. You guys are right, I should just break the engine in and see how it goes. I was just wondering because the car seemed to run fine through the RPM range, but when it drops back down to idle you can tell it starts to run rich, almost like it is loading up ya know. I know it's not going to run perfect from the start, but I wasn't sure if these were common things that happen or not.

I'm running a spark plug that is one heat range colder than stock, does that make a difference?

 

Just keep an eye on the oil, making sure that the excess fuel isn't washing down the cylinder walls, and removing the lubrication. Not too good for a brand new engine.

 

Thanks, I'll keep an eye on that too. Normally how long does it take for low tension rings to seat correctly? FWIW they are Ross rings and pistons.