nytrail

dwell??? timing light???

damn i'm 34 and kinda remeber my dad using the timing light when i could barely see into the engine compartment.

of course i can't remeber life without a computer in the living room and a microwave in the kitchen

SanDiegoBert

Must have been a LONG while, since you forgot wires and boots!

MikeyTX

They run real fast from what I've seen

shopdog

Yes, a very mild one. Mainly I leaned out the WOT mixture a bit and bumped the part throttle timing up a bit. Chevy sets the car to run pig rich at WOT, so leaning it out a bit up top can help power without undue risk. Because my car is an automatic, I can get away with a bit more timing down low (this would be risky with a manual because of the possibility of knock when lugging the engine, the auto won't let you lug the engine). This crispens up throttle response with little danger of detonation as long as I use good gas. Both changes help MPG a little bit too.

I avoided being very aggressive with the tune because I travel a lot. That means the car sees different ambient temperatures, different altitudes, and different fuel qualities. It has to stay safe under all of those conditions. An aggressive tune could have found a few more ponies, but it would have been riskier because of where, when, and how I use the car.

Atomic Punk

more likely than not.

shopdog

If the dealer knew about it, and the tune had anything to do with the warranty claim, its likely to be cause for denial under the warranty provisions. For sure it is considered tampering under the Clean Air Act, same as cat delete, long tube headers, etc, and illegal modifications are cause to void a warranty claim. But a tune isn't a visible mod like those others, and is less likely to be noticed by the dealer.

MikeyTX

My dealer is mod friendly. Besides which, they have to prove that the mod is what caused the problem. GM would have a heck of a time proving my Borla catback caused engine failure.

shopdog

Actually, they only have to say the mod caused the problem. Then you have to take them to court and convince the judge that they are wrong. Expensive and time consuming even if you prevail.

ZeusC6

Hmmm, sounds like the tune I want...
where do you live? I can't see from your profile

Bob Dyble

Not only do I still have my dwell meter but several feeler gauges...

The Clevite Kid

Hey, I built my dwell-tach from a Heathkit (remember them?).

Dual points were the bee's knees; one set opens, and the other closes just a couple of degrees later to get the longest dwell, and hence the maximum magnetic saturation, in the coil.

I also made my first car theft-resistant by putting a switched 1000 microfarad electrolytic capacitor in parallel with the normal condensor. It took so long to discharge through the coil that the coil could not collapse its field fast enough to generate a spark. Darn hard for even a knowledgeable thief to troubleshoot, too.

andyandy98

Tommy D

Don't think so if he has HP tuners. I got it and have started to play around. I have run several scans to see how our two Corvettes are running. Now that I have information to play with I have just started to look at the factory tune. There is a entire tab for spark dwell. There are tables to set the base dwell time, base dwell modifier (dwell vs ignition volts vs engine coolant temperature), Max dwell time vs rpm and min dwell time vs rpm.

From what I can see our cars are very sensitive to changes in coolant temperature. I am not experienced enough to make changes so maybe Shopdog can walk us through which tables he changed and how he did it.

Whiterock1

Well said. That is one reason I went with the Predator: conservative, but hits the right spots: leans AFR and kills TM--plus CAGS. I have noticed much better response and feel the added hp at wot--thought I was doing about 100 yesterday, looked at the speedo and it was passing thru 125! Sorry officer, can I buy you a doughnut...At this altitude, 6700', lean is the way to go, and the Aircharger with open shroud helps a lot too. You can adjust all the key parameters with the tool, also--although I need to learn a lot more before I play with that, but a little leaner, maybe 12.5, seems like a good play. The knock sensors are excellent on the C6, so that is a good safety net for poor gas, as well. All in all, I wanted better off idle response and that seems to be there--it started a lot better after I opened the shroud from stop in 1st gear, and feels better now. Plus, I can feel the TM disable--again in responsiveness. Bullets are the only other mod, so a full blown dyno tune, to me, isn't worth it. The Predator lets me go back to stock, and the open shroud can go back to closed in 30 seconds. I'm happy with my setup.

NORTY

Never been married, huh?

SwissDude

I am about to get my 2007 C6 A6 tuned here in Switzerland by Digital Tuning.

After talking to them today, they said that they only modify the mixture and the spark timing.

Can somebody explain what "defeating abuse mode" means (in other words, if abuse mode is still "enabled" what does it prevent you from doing)?

TIA

Me262

Forgot the new rotor too.

Tuner@Straightline

Dwell Meter, I think I've seen one of those in a Museum right next to the Steam Engines......


On to the topic. What we do as tuners, or atleast what we should do is maximize the fuel and spark to bring about the most power that we can for the amount of air that the engine is moving, without breaking anything. I think that is as simple as it can be put. If you don't want a headache, then stop reading now.

On to things a little more complex. Then engine of any car is basically an air pump. Only so much power can be made based on the amount of air entering the cylinders. That is a mechanical limitation. Nothing a tuner can do is going to change that.

So how exactly do we "tune?" Tuning is basically callibrating the air metering the sensors (MAF/MAP) and then programming the computer so that certain "commands" occur. For instance, at WOT, if I am "commanding" and AFR of 12.9:1, and my actual AFR is 12.2:1 then I know that what ever fuel table the car is reading off of is out of calibration by about 5.5%. Now my job is to find out where I need to take 5.5% of fuel out of in order to reach my "Command" AFR. How is this done? First thing to do is set your command AFR. This is usually already done, the factory setting is 14.67xxxx. This is also known as Stoich. Now at WOT, the PE table is a fuel multiplier. By setting those values to 1.13 (14.7/1.13) we car commanding a WOT AFR of 13:1. This is usually where I see the most power for LSx based motors. The next thing to do is to set the "triggers" or enablers to enter PE enrichment mode. They are usually RPM, Load (Kpa), and TPS. Once all three values have been reached, the fuel multiplication occurs. The next thing to do is look to see if any of the fuel table cells are not what I'm commanding. If so I need to know by how much to correct their values.

Once I'm happy with my fuel curve, then it's time to work on spark. I usually start with a low amount of advance, and work up until I see very little change in HP from the dyno, or I start detecting KR from the scans. Once this happens, I pull a plug and examine them. If need be I'll change a few plugs and repeat the pull to see where the timing mark is.

By no means are these intended to be detailed directions to tuning your own car, and I do not recomend changing any fueling or timing advance tables without a wideband and scanner that can detect KR. There is a lot more to tuning, like deleting the torque management, setting the fan temps, shift points, start up issues, idle issues, over all drivablity, bucking, surging, shift firmness, tcc lock up, skip shift elimination....those are all things that should be addressed as well, but the less modifications done to a car, the less any of those things will become an issue.

As far as when somebody should get a tune, that's completely up to the owner of the car. I'd say once you do headers, you should look into it. If you plan on further upgrades (heads/cam/power adder)within the next year or so, then hold off, but once you've done internal modifications, or the headers are the only thing you plan on doing for the next year or more, then it would be worth the time and money for a tune.

I hope some knowledge was gained in my randomness.

w.f.tracy

Probably so, but some of us geezers like to have our memories jogged. Thanks for the trip down memory lane to the days when, for some, a tune meant loosening and then turning the distributor until the engine "sounded" right.

Zig

yep, sure do. i built my first computer using one of their kits for my 7th grade science project.

do you remember the robot they had? you could build an r2d2 type of robot, complete with arm and proximety sensors.